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Functional amyloids, beneficial to the organism producing them, are found throughout life, from bacteria to humans. While disease‐related amyloids form by uncontrolled aggregation, the fibrillation of functional amyloid is regulated by complex cellular machinery and optimized sequences, including so‐called gatekeeper residues such as Asp. However, the molecular basis for this regulation remains unclear. Here we investigate how the introduction of additional gatekeeper residues affects fibril formation and stability in the functional amyloid CsgA from E. coli. Step‐wise introduction of additional Asp gatekeepers gradually eliminated fibrillation unless preformed fibrils were added, illustrating that gatekeepers mainly affect nucleus formation. Once formed, the mutant CsgA fibrils were just as stable as wild‐type CsgA. HSQC NMR spectra confirmed that CsgA is intrinsically disordered, and that the introduction of gatekeeper residues does not alter this ensemble. NMR‐based Dark‐state Exchange Saturation Transfer (DEST) experiments on the different CsgA variants, however, show a decrease in transient interactions between monomeric states and the fibrils, highlighting a critical role for these interactions in the fibrillation process. We conclude that gatekeeper residues affect fibrillation kinetics without compromising structural integrity, making them useful and selective modulators of fibril properties. [ABSTRACT FROM AUTHOR]

Background: Identification of auditory processing disorders is achieved using questionnaires along with linguistic, non-linguistic, and auditory processing tests. Notably, the questionnaires "Children's Auditory Performance Scale" (CHAPS) and "Auditory Processing Domain Questionnaire" (APDQ) are widely recognized and used. The current study investigated the psychometric properties of the CHAPS and APDQ in Greek Cypriot children. Methods: The CHAPS and APDQ questionnaires were completed by parents of 40 Greek Cypriot children, 16 typically developing (TD) children, and 24 children with a history of Speech Sound Disorders (SSDs). Results: There were significant differences between the two groups on both questionnaires. Cronbach's alpha was calculated at α = 0.922 for the CHAPS total score and α = 0.926 for the APDQ total score. The Receiver Operating Curve (ROC) analysis provided a cut-off point equal to −0.30 (AUC 0.849, p < 0.001) for CHAPS and a cut-off point equal to 90.00 (AUC 0.820, p < 0.001) for APDQ. Significant positive Spearman ρ correlations were observed between the CHAPS and APDQ (ρ = 0.639, p = 0.001). Conclusions: The CHAPS and APDQ can identify distinct auditory processing characteristics between in children with SSDs and TD children. [ABSTRACT FROM AUTHOR]

Background: Identification of auditory processing disorders is achieved using questionnaires along with linguistic, non-linguistic, and auditory processing tests. Notably, the questionnaires “Children’s Auditory Performance Scale” (CHAPS) and “Auditory Processing Domain Questionnaire” (APDQ) are widely recognized and used. The current study investigated the psychometric properties of the CHAPS and APDQ in Greek Cypriot children. Methods: The CHAPS and APDQ questionnaires were completed by parents of 40 Greek Cypriot children, 16 typically developing (TD) children, and 24 children with a history of Speech Sound Disorders (SSDs). Results: There were significant differences between the two groups on both questionnaires. Cronbach’s alpha was calculated at α = 0.922 for the CHAPS total score and α = 0.926 for the APDQ total score. The Receiver Operating Curve (ROC) analysis provided a cut-off point equal to −0.30 (AUC 0.849, p < 0.001) for CHAPS and a cut-off point equal to 90.00 (AUC 0.820, p < 0.001) for APDQ. Significant positive Spearman ρ correlations were observed between the CHAPS and APDQ (ρ = 0.639, p = 0.001). Conclusions: The CHAPS and APDQ can identify distinct auditory processing characteristics between in children with SSDs and TD children.

Aquaporin (AQP) is a water channel protein from the family of transmembrane proteins which facilitates the movement of water across the cell membrane. It is ubiquitous in nature, however the understanding of the water transport mechanism, especially for AQPs in microbes adapted to low temperatures, remains limited. AQP also has been recognized for its ability to be used for water filtration, but knowledge of the biochemical features necessary for its potential applications in industrial processes has been lacking. Therefore, this research was conducted to express, extract, solubilize, purify, and study the functional adaptations of the aquaporin Z family from Pseudomonas sp. AMS3 via molecular approaches. In this study, AqpZ1 AMS3 was successfully subcloned and expressed in E. coli BL21 (DE3) as a recombinant protein. The AqpZ1 AMS3 gene was expressed under optimized conditions and the best optimized condition for the AQP was in 0.5 mM IPTG incubated at 25°C for 20 h induction time. A zwitterionic mild detergent [(3‐cholamidopropyl) dimethylammonio]‐1‐propanesulfonate was the suitable surfactant for the protein solubilization. The protein was then purified via affinity chromatography. Liposome and proteoliposome was reconstituted to determine the particle size using dynamic light scattering. This information obtained from this psychrophilic AQP identified provides new insights into the structural adaptation of this protein at low temperatures and could be useful for low temperature application and molecular engineering purposes in the future. [ABSTRACT FROM AUTHOR]

Amberlite has been shown to be an appropriate material for the adsorption of organic contaminants from aqueous solutions. In addition, Amberlite XAD-2 has been successfully used, as an alternative to Bio-Beads, to remove Triton X-100 from protein solutions, such as from samples of solubilized membrane proteins. However, Amberlite has not been tested as an adsorbent when a mixture of detergents is necessary to solubilize and refold a target protein. Here the authors show that Amberlite XAD-4 can be appropriately used to aid the purification process of proteins solubilized from inclusion bodies with the ternary detergent system consisting of Sarkosyl, Triton X-100 and CHAPS.

The utility of CHAPS-PC, a detergent combination for solubilizing membrane proteins, was investigated as a substitute to digitonin solution for extracting rhodopsin in the measurement of spectral sensitivity in squid. Microvilli of the photoreceptor outer segments were collected and purified from the retinas of three species, Uroteuthis edulis, Todarodes pacificus, and Heterololigo bleekeri, using sucrose density-gradient centrifugation. The difference in the absorption maximum (λmax) of rhodopsin between extraction with CHAPS-PC or with digitonin was 0–3 nm for all species. The λmax values of the three squid species were 488–490, 478–480, and 488–491 nm, respectively, which aligns well with values reported in previous studies. CHAPS and PC are less expensive than digitonin, which is advantageous when conducting repeated experiments. We hope that the present procedure for the extraction of visual pigments offers an improved fisheries technology that will be used to better understand the ecology of diverse squid species. [ABSTRACT FROM AUTHOR]

The interaction between Hen Egg White Lysozyme (HEWL) and 3-[(3-cholamidopropyl) dimethyl-ammonio]-1-propanesulphonate (CHAPS) was examined using biophysical techniques (spectrofluorometric, circular dichroism, and dynamic light scattering) at pH 9.0. The results obtained from multi-techniques showed that CHAPS interact with the HEWL strongly and affects protein conformations. The far-UV CD results suggest that lower as well as higher (1.0–15.0 mM) concentrations of CHAPS are inducing α-helical structure in HEWL. The near-UV CD and fluorescence data indicated that the tertiary structure of HEWL is alter in the presence of CHAPS. The ANS dye binding suggest that the exposure of HEWL tertiary structure is dependent on CHAPS concentration. As the concentrations of CHAPS is increasing the exposure of HEWL tertiary structure is also increasing and maximum exposure was found at 15.0 mM of CHAPS concentrations. The hydrodynamic radii of HEWL is also increase in the presence of sub-micellar and micellar concentrations of CHAPS because the tertiary structure of HEWL is disrupted. Overall, the results suggest that CHAPS is inducing secondary structure and disrupting tertiary structure of HEWL. This study provides detailed interaction of CHAPS with HEWL at the molecular level.

BACKGROUND 3‐[(3‐Cholamidopropyl)dimethylammonio]‐1‐propanesulfonate (CHAPS) is a zwitterionic detergent commonly utilized in protein biochemistry‐based applications. This study demonstrates for the first time the successful phase separation of CHAPS via salt addition. Elucidation of consolute solution temperature behavior and determination of binodal curve and tie‐line length (TLL) enabled the subsequent development of CHAPS‐based phase separation systems. The systems were then evaluated using a low‐molecular‐weight dye, Coomassie Brilliant Blue (CBB), and integral membrane protein, cytochrome P450 (CYP) 2C19. RESULTS: The anionic identity of salts was found to be critical, with sulfate and phosphate salts being successful in inducing phase separation of CHAPS at 4 °C. CHAPS and (NH4)2SO4 mixtures were later found to have an upper consolute solution temperature (UCST). Binodal data were collected and fitted to an equation to allow determination of the minimum amount of CHAPS and (NH4)2SO4 required for the formation of phase separation systems. In CHAPS/(NH4)2SO4 systems, CBB was found to partition extensively to the micelle‐rich phase (MRP) with an extraction yield of 83 ± 0.32%, while CYP 2C19 was successfully recovered with an extraction yield of 46 ± 7.58%. CONCLUSION: Phase separation of CHAPS achieved at low temperature via sulfate salt addition can be exploited for the extraction of hydrophobic molecules. The outcomes of this study propound the scope for application of CHAPS as a component of phase separation systems. © 2019 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Although pulmonary diseases account for a large number of deaths in the world, most have no treatment other than transplantation. New therapeutic methods for lung treatment include lung tissue engineering and regenerative medicine. Lung decellularization has been used to produce an appropriate scaffold for recellularization and implantation. We investigated 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) with sodium dodecyl sulfate (SDS) and Triton X-100 detergents for effecting rat lung decellularization. We evaluated using conventional histology, immunofluorescence staining and SEM methods for removing nuclear material while leaving intact extracellular matrix proteins and three-dimensional architecture. We investigated different concentrations of CHAPS, SDS and Triton X-100 for different periods. We found that 2 mM CHAPS + 0/1% SDS for 48 h was the best among the treatments investigated. Our method can be used to produce an appropriate scaffold for recellularization by stem cells and for investigations ex vivo and in vivo. [ABSTRACT FROM AUTHOR]

Background: Current esophageal treatment is associated with significant morbidity. The gold standard therapeutic strategies are stomach interposition or autografts derived from the jejunum and colon. However, severe adverse reactions, such as esophageal leakage, stenosis and infection, accompany the above treatments, which, most times, are life threating. The aim of this study was the optimization of a decellularization protocol in order to develop a proper esophageal tissue engineered construct. Methods: Rat esophagi were obtained from animals and were decellularized. The decellularization process involved the use of 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) and sodium dodecyl sulfate (SDS) buffers for 6 h each, followed by incubation in a serum medium. The whole process involved two decellularization cycles. Then, a histological analysis was performed. In addition, the amounts of collagen, sulphated glycosaminoglycans and DNA content were quantified. Results: The histological analysis revealed that only the first decellularization cycle was enough to produce a cellular and nuclei free esophageal scaffold with a proper extracellular matrix orientation. These results were further confirmed by biochemical quantification. Conclusions: Based on the above results, the current decellularization protocol can be applied successfully in order to produce an esophageal tissue engineered construct. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Solvent Paramagnetic Relaxation Enhancement has been introduced to study the detailed aggregation mode of CHAPS. • The core and surface of the micelle are formed mainly by the head, and tail of CHAPS, respectively. • The micelle in M2 state is mostly like to be a double layer structure with relatively tight but still messy aggregation Abstract CHAPS is a typical zwitterionic detergent widely used in protein purification. It has two peculiar aggregation states, whose aggregation patterns are still controversial and uncertain. In this paper, we analyzed the aggregation pattern of CHAPS by 1H solvent Paramagnetic Relaxation Enhancement (sPRE) experiment. It was found that the 1H sPREs of head groups of CHAPS are much smaller than those of the tail groups, and all of them become smaller simultaneously when the concentration of CHAPS is above CMC2. In addition, the sPREs of those protons in the steroid ring were found to be very similar to each other in both micellar states (M1 and M2). These results indicated that the micellar core of CHAPS is mainly formed by its steroid head which aggregate disorderly. On the other hand, a transition from single to double layer micelle is most likely to happen when the concentration of CHAPS is above CMC2. The micelle in M2 state is formed by the aggregation of the partially disordered primary ones as well. Furthermore, the STD (Saturation Transfer Difference) experiment showed that the apparent coherence transfer rates between water and those OH near protons at the steroid head are slower in M2 state, revealing that the CHAPS aggregate loosely in M1 state, but more tightly in M2 state, which may be driven by the increased hydrophobic interactions between the steroid groups of nearby CHAPS molecules, as well as the hydrogen bond between OH in the hydrophobic side and SO 3 −1, CO, or HN in the hydrophilic side of different molecules, which consequently extrude the water and stabilize the micelle. [ABSTRACT FROM AUTHOR]

Solubilization of membrane proteins by amphiphilic detergents represents a crucial step in studies of membrane proteins in which proteins and lipids in natural membranes are dissociated giving rise to mixed clusters of proteins, lipids and detergents in the aqueous dispersion. Although solubilization is a popular method, physicochemical principles underlying solubilization are not well understood. In this work, we monitored solubilization of the bovine hippocampal serotonin 1A receptor, a representative member of the GPCR family, using membrane dipole potential measured by a dual fluorescence ratiometric approach with a potential-sensitive fluorophore. Our results show that membrane dipole potential is a good indicator of solubilization and reflects the change in dipolar environment upon solubilization due to dipolar reorganization associated with solubilization. To the best of our knowledge, these results constitute the first report linking membrane dipole potential with solubilization. We envision that these results are potentially useful in providing a molecular mechanism for membrane protein solubilization. [ABSTRACT FROM AUTHOR]

Background: Current esophageal treatment is associated with significant morbidity. The gold standard therapeutic strategies are stomach interposition or autografts derived from the jejunum and colon. However, severe adverse reactions, such as esophageal leakage, stenosis and infection, accompany the above treatments, which, most times, are life threating. The aim of this study was the optimization of a decellularization protocol in order to develop a proper esophageal tissue engineered construct. Methods: Rat esophagi were obtained from animals and were decellularized. The decellularization process involved the use of 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS) and sodium dodecyl sulfate (SDS) buffers for 6 h each, followed by incubation in a serum medium. The whole process involved two decellularization cycles. Then, a histological analysis was performed. In addition, the amounts of collagen, sulphated glycosaminoglycans and DNA content were quantified. Results: The histological analysis revealed that only the first decellularization cycle was enough to produce a cellular and nuclei free esophageal scaffold with a proper extracellular matrix orientation. These results were further confirmed by biochemical quantification. Conclusions: Based on the above results, the current decellularization protocol can be applied successfully in order to produce an esophageal tissue engineered construct.

Ferritin naturally has a shell-like architecture with inner/outer surfaces, which can be applied as a nanovehicle of biologically active molecules. Herein, a CHAPS-involved scheme was arranged to fabricate the ferritin-agaro oligosaccharide-epigallocatechin gallate (EGCG) nanoparticle (FAE) partitioned by the ferritin shell. A concentration (10 mM) of CHAPS expanded the channel size of phytoferritin by remarkably improving the rate of iron release and facilitated the encapsulation of EGCG without disassembling the ferritin. The encapsulating ratio of EGCG reached (10.8 ± 0.13) %, about 17.2 EGCG per ferritin cage. Meanwhile, agaro oligosaccharide could attach on the ferritin outer surface with a stoichiometric number of 12.1 ± 0.31 (agaro oligosaccharide/ferritin) and a binding constant of (3.25 ± 0.23) × 105 M−1. The diameter of FAE was maintained at ∼12 nm, and the hydrodynamic radius (R H) was 7.61 nm, proving that the agaro oligosaccharide attachment and the encapsulation of EGCG retained the ferritin morphology. In addition, the CHAPS acted in alleviating the association effect of the ferritin when forming FAE. Moreover, the agaro oligosaccharide as the second layer attaching on the ferritin surface significantly improved the EGCG stability in FAE towards heating treatment and controlled the release of EGCG in a more sustained manner. This study highlights the role of CHAPS and fabricates a triple-layer nanoparticle in a simple way, which expands the fabrication method of oligosaccharide-protein-polyphenol polymers and is conducive to the stability of food bioactive molecules. [Display omitted] • CHAPS could induce the expansion of the size of the ferritin channels. • CHAPS enabled the formation of ferritin-AO-EGCG triple-layer nanoparticle (FAE). • CHAPS alleviated association effect of ferritin and promoted EGCG encapsulation. • AO attaching on the ferritin improved the thermal stability of EGCG. • AO attaching on the ferritin sustained the controlled release of EGCG. [ABSTRACT FROM AUTHOR]

Human S100A9 (Calgranulin B) is a Ca 2 + -binding protein, from the S100 family, that often presents as a homodimer in myeloid cells. It becomes an important mediator during inflammation once calcium binds to its EF-hand motifs. Human RAGE protein (receptor for advanced glycation end products) is one of the target-proteins. RAGE binds to a hydrophobic surface on S100A9. Interactions between these proteins trigger signal transduction cascades, promoting cell growth, proliferation, and tumorigenesis. Here, we present the solution structure of mutant S100A9 (C3S) homodimer, determined by multi-dimensional NMR experiments. We further characterize the solution interactions between mS100A9 and the RAGE V domain via NMR spectroscopy. CHAPS is a zwitterionic and non-denaturing molecule widely used for protein solubilizing and stabilization. We found out that CHAPS and RAGE V domain would interact with mS100A9 by using 1 H- 15 N HSQC NMR titrations. Therefore, using the HADDOCK program, we superimpose two binary complex models mS100A9-RAGE V domain and mS100A9-CHAPS and demonstrate that CHAPS molecules could play a crucial role in blocking the interaction between mS100A9 and the RAGE V domain. WST-1 assay results also support the conclusion that CHAPS inhibits the bioactivity of mS100A9. This report will help to inform new drug development against cell proliferation. [ABSTRACT FROM AUTHOR]

Discussion of the Court of Appeal’s decision in the Tidal Energy v Bank of Scotland case relating to the question of whether a customer had been taken to contract on the basis of standard banking practice with regard to the use of unique identifiers in a CHAPS transaction. Assesses the knowledge of the customer as to this issue and the importance of commercial common sense. [ABSTRACT FROM AUTHOR]

Use of Cry1Ac δ-endotoxin of Bacillus thuringiensis (Bt) has revolutionized crop protection especially in cotton. Large quantities of Cry1Ac protein are needed for several basic studies. Heterologous expression in E. coli facilitates production of large quantities of recombinant Cry1Ac protein. However, earlier studies reported that E. coli expressed recombinant protein leads to large variations in LC50 values. Here we report a method of active Cry1Ac δ-endotoxin purification that is simple, robust and exhibits higher toxicity with consistent results in insect bioassays. In this protocol proteolysis separates completely folded Cry1Ac δ-endotoxin molecules (active toxin) from nonnative protein folding forms and other host proteins, followed by extraction of active Cry1Ac toxin by micro filtration. Insect bioassay of purified Cry1Ac toxin with Helicoverpa armigera showed 125 times enhanced toxicity (LC50 40 pg/cm2) as compared to the earlier reports (LC50 ng/cm2) 4.5 to 3500 ng/cm2. These results provide a new prospective in determination of baseline susceptibility, monitoring resistance development and utilization of its potential. [ABSTRACT FROM AUTHOR]

Human and porcine cysticercosis is caused by the larval stage of the flatworm Taenia solium (Cestoda). The protein extracts of T. solium cysts are complex mixtures including cyst's and host proteins. Little is known about the influence of using different detergents in the efficiency of solubilization–extraction of these proteins, including relevant antigens. Here, we describe the use of CHAPS, ASB-14 and Triton X-100, alone or in combination in the extraction buffers, as a strategy to notably increase the recovery of proteins that are usually left aside in insoluble fractions of cysts. Using buffer with CHAPS alone, 315 protein spots were detected through 2D-PAGE. A total of 255 and 258 spots were detected using buffers with Triton X-100 or ASB-14, respectively. More protein spots were detected when detergents were combined, i.e., 2% CHAPS, 1% Triton X-100 and 1% ASB-14 allowed detection of up to 368 spots. Our results indicated that insoluble fractions of T. solium cysts were rich in antigens, including several glycoproteins that were sensitive to metaperiodate treatment. Host proteins, a common component in protein extracts of cysts, were present in larger amounts in soluble than insoluble fractions of cysts proteins. Finally, antigens present in the insoluble fraction were more appropriate as a source of antigens for diagnostic procedures. [ABSTRACT FROM AUTHOR]

Neurotensin receptor type 1 (NTS1) is a G protein‐coupled receptor (GPCR) that affects cellular responses by initiating a cascade of interactions through G proteins. The kinetic details for these interactions are not well‐known. Here, NTS1‐nanodisc‐Gαs and Gαi1 interactions were studied. The binding affinities of Gαi1 and Gαs to NTS1 were directly measured by surface plasmon resonance (SPR) and determined to be 15 ± 6 nM and 31 ± 18 nM, respectively. This SPR configuration permits the kinetics of early events in signalling pathways to be explored and can be used to initiate descriptions of the GPCR interactome.Little is known of the kinetics of interactions between GPCRs and their signalling partners. NTS1 binds Gαi1 and Gαs with affinities of 15±6nM and 31±18nM (SE), respectively. This SPR assay may be applicable to multiple partners in the signalling cascade. We provide the first direct evidence for GPCR‐G protein coupling in nanodiscs. [ABSTRACT FROM AUTHOR]

Abstract: Kinetics of cerium(IV) oxidation of aliphatic alcohols: ethanol, propanol, propan-2-ol, 1-butanol and 2-butanol were studied at 30°C in the presence and absence of surfactants in acidic medium. The reaction was studied under pseudo-first-order conditions, [alcohol]T ≫[Ce(IV)]T. Ir(III)-salt used as catalyst had a significant effect on reaction rate. Cationic surfactant CPC (N-cetylpyridinium chloride) inhibits the reaction rate but zwitterionic surfactant CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) catalyzes the oxidation reaction significantly. CMC value of CHAPS was determined by a spectrofluorometer. The reaction rate increased with increase in the acid concentration of the medium. NMR and FTIR spectra confirmed the oxidized products. The aggregation of surfactants in the reaction condition was studied through Scanning Electron Microscope (SEM) and Transmission Electron Microscope (TEM). Dynamic light scattering (DLS) was used to characterize the shape changes of the aggregates. The variations of the reaction rates for the different alcohols in the presence of surfactants and metal ion catalyst are discussed qualitatively in terms of Berezin's model, nature of surfactants, and charge of surfactants. Ir(III) in association with CHAPS micellar catalyst exhibited ~500–2000fold rate enhancements compared to the uncatalyzed reaction path. [Copyright &y& Elsevier]

Highlights: [•] BaxΔC interacts with CHAPS directly, but relatively weakly. [•] BaxΔC interacts with BaxBH3 or BimBH3 peptide directly, and relatively strongly. [•] Binding with BaxBH3 or BimBH3 resulted in substantial spectral changes to BaxΔC. [•] BaxBH3 or BimBH3 bounded BaxΔC is monomeric, but dimerizes when CHAPS is presented. [Copyright &y& Elsevier]

Abstract: Anionic biological surfactant sodium cholate (NaC) and the zwitterionic nontoxic surfactant CHAPS (3-[(3-cholamidopropyl)dimethylammonio]-1-propanesulfonate) having common steroidal skeleton have not been studied in a comparative level to explore their amphiphilic behaviors separately and in mixed states. Their adsorption at the interface in relation to self-association in solution has been examined in both pure and mixed states with reference to detailed thermodynamic analysis of their surface chemical and solution behaviors. Their head group differences are responsible for the differences in their properties viz. critical micelle concentration (CMC), aggregation number (N), hydrodynamic diameter, Gibbs surface excess (Γ max), minimum head group area (A min), mixed micelle composition and their mixing ideality/nonideality. Although the CMC values found from tensiometry and isothermal titration calorimetry (ITC) are in good agreement, the standard enthalpy of micellization ( ) found from ITC at different temperatures are different from that evaluated by the van't Hoff method. This is because van't Hoff rationale is a differential method which estimates the enthalpy of the monomer ↔ micelle equilibrium process whereas calorimetry is an integral process that evaluates all probable/possible processes in addition to monomer to micelle conversion. Results are analyzed, compared and discussed in the light of physicochemical parameters of pure NaC and CHAPS and their mixtures. These fundamental findings are considered prospective in pharmaceutical, biochemical and biomedical applications of the studied bio-friendly amphiphiles. [Copyright &y& Elsevier]

Numerous studies have demonstrated that neighborhood context contributes to variations in morbidity and mortality. This body of work includes a burgeoning literature that links adverse neighborhood characteristics (e.g., neighborhood poverty and perceptions of disorder and dangerousness) with poorer sleep outcomes. During the COVID-19 pandemic, many neighborhoods exhibited socioeconomic downturns and escalations in crime and violence. The question is the extent to which these changes in neighborhood conditions have impacted the sleep quality of residents. In this paper, we use original survey data from the 2021 Crime, Health, and Politics Survey (CHAPS), a national probability sample of adults living in the U.S., to formally test whether changes in perceptions of neighborhood dangerousness during the pandemic are associated with sleep quality during the same period. Regression analyses show that while reports of a neighborhood becoming safer during the pandemic are associated with better sleep quality, reports of a neighborhood becoming more dangerous are associated with worse sleep quality. Mediation analyses also indicate that the association between increased neighborhood dangerousness and poorer sleep quality is partially explained by a concurrent deterioration in diet quality, but not increases in alcohol or cigarette consumption. We conclude with a discussion of the implications of our findings for research and policy on neighborhood context and sleep. [ABSTRACT FROM AUTHOR]

Myelin sheath is a lipid-rich membrane, consisting of 70% lipid and 30% proteins, that is involved in physiological and pathological processes. For this reason its protein composition has been often investigated, principally by two-dimensional electrophoresis; however, the consistent lipid content makes it difficult to obtain good proteins separation. To improve the resolution of myelin proteins in a denaturing monodimensional gel electrophoresis, we examined several mixtures for the denaturation of the sample, utilizing different detergents and reducing agents. The definition of the protein pattern was analyzed by both “Blue Silver” Coomassie staining and Western Blot analysis against myelin basic protein, one of the most represented myelin proteins. The best resolution is observed when the sample was incubated with a mixture containing 1.25% dithiothreitol, 4Murea, and 1% dodecyl maltoside or 1 % 3-[(3-cholamidopropyl)-dimethylammonio]-1-propanesulfonate, prior to addition of denaturing agents. In conclusion, this work describes a novel method to improve the separation of myelin proteins in a monodimensional gel electrophoresis. It may be also useful for investigating other lipid-rich samples. [ABSTRACT FROM AUTHOR]

Abstract: One unique feature in cyanoprokaryotes, rhodophytes, and cryptophytes is the presence of phycobilin pigments-these water soluble pigments can absorb red, orange, yellow, and green light enhancing the spectral range available for cellular conversion to chemical energy. The presence of phycobilin pigment complexes can be detected using fluorescence, or absorbance measures. Efficient detection of these compounds is essential for use in calibrating absorbance in remote sensing or in physiological studies. The standard procedure for phycobilin analysis involves sonication, extraction in buffer potentially coupled with additional digestion steps using enzymes, repeated freeze and thawing cycles, followed by filtration, and spectrophotometric analyses. An alternative method, using asolectin-CHAPS ((3-[(3-cholamidopropyl)dimethylammonio]propanesulfonic acid – AC)) solution for extraction, and three cycles of freeze/thawing/sonication, was compared to the phosphate buffer (PB) standard procedure. Cultures of both coccoid and filamentous cyanoprokaryota had improved extraction efficiency (38–80%) using AC. After two complete extractions, no pigment was detectable in AC and near baseline fluorescence was observed in the cell pellet, whereas the PB extraction method removed <90% of the phycobilins after two extractions. Phycocyanin concentration measured by AC extraction was better correlated to lipophilic pigment concentration than using phosphate buffer extraction. AC buffered to pH 6.7 was more effective than AC 3.75. One potential source of experimental error was determined to be the use of a baseline correction for the extraction buffer, not the sample. [Copyright &y& Elsevier]

True lipolytic activity is observed in different subcellular fractions of germinating sunflower seedlings (Helianthus annuus L.) in delipidated oleosomes and microsomes. Triacylglycerol lipase (EC. 3.1.1.3) catalyses the first catabolic step of lipolysis. To our knowledge, this plant lipase has not yet been identified. Our aim was to develop a method to collect the lipase for further studies. An immunological method was used to capture sunflower seedling lipase from oleosomes and microsomes. This method uses an immunoaffinity column prepared with polyclonal antibodies (anti-P-61) directed against oleosomal activity. Our results verify that we have successfully adapted a purification procedure of plant lipase using anti-P-61. Since the eluted lipolytic activity is distributed among diverse proteic peaks, we changed the elution procedure: the introduction of CHAPS, a zwitterionic detergent, allowed us to recover all the lipolytic activity in a single proteic peak. This may help us to characterise the studied lipase. [ABSTRACT FROM AUTHOR]

The Faster Payments Service (FPS) was launched in 2008 and has witnessed significant growth since its inception. In 2010, the second full year of operation, volumes rose above anticipated levels, and new products and services supported by this 24x7 immediate payment capability are starting to evolve. VocaLink has undertaken much work to assist banks and their customers in the implementation of FPS within their businesses and to leverage the opportunities it provides to offer improved service level agreements. Some of these innovations are markers for a convergence between card, automated clearing house and Real Time Gross Settlement payment behaviours. Studies since 2008 have witnessed a slow but significant change in customer behaviour and expectation. Accord and VocaLink conducted research in 2010 to determine consumer and small business impressions and the take up of FPS. This independent research is based on a reasonable sample size (more than 2000 individuals and 300 small and medium-sized enterprises (SMEs)), and the results point to a widespread consumer understanding of a change in payment services, but without clear understanding of FPS in itself as a service or brand proposition. It is perceived by the consumer to be the capability of a bank, rather than a network or scheme capability. A clear shift has been seen in expectation of service levels and the art of the possible. In a separate study, the benefits of a mobile bank-account-to-bank-account payment service was examined, and the SME sector's willingness to pay for such a service to reduce reliance on cheques and cash. [ABSTRACT FROM AUTHOR]

Abstract: Histo-aspartic protease (HAP) from Plasmodium falciparum is an intriguing aspartic protease due to its unique structure. Our previous study reported the first recombinant expression of soluble HAP, in its truncated form (lys77p-Leu328) (p denotes prosegment), as a thioredoxin (Trx) fusion protein Trx–tHAP. The present study found that the recombinant Trx–tHAP fusion protein aggregated during purification which could be prevented through the addition of 0.2% CHAPS. Trx–tHAP fusion protein was processed into a mature form of tHAP (mtHAP) by both autoactivation, and activation with either enterokinase or plasmepsin II. Using gel filtration chromatography as well as sedimentation velocity and equilibrium ultracentrifugation, it was shown that the recombinant mtHAP exists in a dynamic monomer–dimer equilibrium with an increasing dissociation constant in the presence of CHAPS. Enzymatic activity data indicated that HAP was most active as a monomer. The dominant monomeric form showed a K m of 2.0μM and a turnover number, k cat, of 0.036s−1 using the internally quenched fluorescent synthetic peptide substrate EDANS–CO–CH2–CH2–CO–Ala-Leu-Glu-Arg-Met-Phe-Leu-Ser-Phe-Pro–Dap–(DABCYL)–OH (2837b) at pH 5.2. [Copyright &y& Elsevier]

Abstract: Fluorescence probing, and ζ-potential measurements have been used to study the interactions between the zwitterionic surfactant 3-[(3-cholamidopropyl)-dimethyl-ammonium]-1-propanesulphonate, CHAPS and two polyelectrolytes with different electric charge. The polyelectrolytes chosen are poly (diallyl-dimethyl-ammonium chloride), PDADMAC, and poly (sodium styrene sulphonate), PSS. Results show that the zwitterionic surfactant CHAPS interacts with both, polyanion and polycation molecules, resulting in polymer–surfactant micelles. The dominating factor in this interaction is the electrostatic attraction. We found that the ζ-potential of polymer–surfactant micelles can be modulated by the addition of different type of polyelectrolytes or modifying the polymer concentration. Using dynamic surface tension measurements we estimate the micelle dissociation rate constants. Results show that the addition of polymers increases the micelle lifetime. [Copyright &y& Elsevier]

Abstract: Analyte loss due to non-specific binding, especially container surface adsorption, is not uncommon in the quantitative analysis of urine samples. In developing a sensitive LC–MS/MS method for the determination of a drug candidate, BAF312, in human urine, a simple procedure was outlined for identification, confirmation and prevention of analyte non-specific binding to a container surface and to recover the ‘non-specific loss’ of an analyte, if no transfer has occurred to the original urine samples. Non-specific binding or container surface adsorption can be quickly identified by using freshly spiked urine calibration standards and pre-pooled QC samples during a LC–MS/MS feasibility run. The resulting low recovery of an analyte in urine samples can be prevented through the use of additives, such as the non-ionic surfactant Tween-80, CHAPS and others, to the container prior to urine sample collection. If the urine samples have not been transferred from the bulk container, the ‘non-specific binding’ of an analyte to the container surface can be reversed by the addition of a specified amount of CHAPS, Tween-80 or bovine serum albumin, followed by appropriate mixing. Among the above agents, Tween-80 is the most cost-effective. β-cyclodextrin may be suitable in stabilizing the analyte of interest in urine via pre-treating the matrix with the agent. However, post-addition of β-cyclodextrin to untreated urine samples does not recover the ‘lost’ analyte due to non-specific binding or container surface adsorption. In the case of BAF312, a dynamic range of 0.0200–20.0ng/ml in human urine was validated with an overall accuracy and precision for QC sample results ranging from −3.2 to 5.1% (bias) and 3.9 to 10.2% (CV), respectively. Pre- and post-addition of 0.5% (v/v) Tween-80 to the container provided excellent overall analyte recovery and minimal MS signal suppression when a liquid–liquid extraction in combination with an isocratic LC separation was employed. The compound was stable in 0.5% Tween-80 treated human urine QC samples for at least 24h at room temperature, after three freeze/thaw cycles with storage at ≤−60°C and for at least 3 months when stored at ≤−60°C. The current work could serve as a simple example in trouble shooting non-specific binding or container surface adsorption in quantitative analysis of urine samples. [Copyright &y& Elsevier]

The 'Faster Payments' scheme run by the CHAPS Clearing Company is rapidly maturing into a fundamental part of the UK payment system. It has already gone much further than envisaged by regulators concerned about float on payments taking several days to clear. It provides a fully real-time payment backbone which has much wider application both within and beyond the UK. In examining the potential for such a payment backbone, one must look beyond the 'Faster' part of Faster Payments and consider the features enabled by real-time processing (including operation 24 x 7, real-time settlement risk management, self-service, third-party connectivity), which provide the platform for transforming payments processing. Roll-out of the UK Faster Payments service has focused on getting the widest possible reach for the basic service, but there are already plans to exploit the service to create new propositions, including remote account to account mobile payments and online payments. Outside the UK, VocaLink's research has indicated that real-time payments are considered inevitable, with implementation supported by a number of initial business propositions, the most favoured being mobile remote payments, echoing the initiative in the UK. Evidence of real-time adoption or aspiration is becoming evident globally, with common themes becoming identifiable. A hypothesis can be advanced from this that real-time or Immediate Payments represent a significant stage in the development of payment systems, and will facilitate the long-term convergence of payment infrastructures. [ABSTRACT FROM AUTHOR]

Abstract: Detergents such as Triton X-100 are often used in drug discovery research to weed out small molecule promiscuous and non-specific inhibitors which act by aggregation in solution and undesirable precipitation in aqueous assay buffers. We evaluated the effects of commonly used detergents, Triton X-100, Tween-20, Nonidet-40 (NP-40), Brij-35, and CHAPS, on the enzymatic activity of West Nile virus (WNV) protease. Unexpectedly, Triton X-100, Tween-20, and NP-40 showed an enhancement of in vitro WNV protease activity from 2 to 2.5-fold depending on the detergent and its concentration. On the other hand, Brij-35, at ⩾0.001% enhanced the protease activity by 1.5-fold and CHAPS had the least enhancing effect. The kinetic analysis showed that the increase in protease activity by Triton X-100 was dose-dependent. Furthermore, at Triton X-100 and Tween-20 concentrations higher than 0.001%, the inhibition of compound B, one of the lead compounds against WNV protease identified in a high throughput screen (IC50 value of 5.7±2.5μM), was reversed. However, in the presence of CHAPS, compound B still showed good inhibition of WNV protease. Our results, taken together, indicate that nonionic detergents, Triton X-100, Tween, and NP-40 are unsuitable for the purpose of discrimination of true versus promiscuous inhibitors of WNV protease in high throughput assays. [Copyright &y& Elsevier]

The interaction between Hen Egg White Lysozyme (HEWL) and 3-[(3-cholamidopropyl) dimethyl-ammonio]-1-propanesulphonate (CHAPS) was examined using biophysical techniques (spectrofluorometric, circular dichroism, and dynamic light scattering) at pH 9.0. The results obtained from multi-techniques showed that CHAPS interact with the HEWL strongly and affects protein conformations. The far-UV CD results suggest that lower as well as higher (1.0–15.0 mM) concentrations of CHAPS are inducing α-helical structure in HEWL. The near-UV CD and fluorescence data indicated that the tertiary structure of HEWL is alter in the presence of CHAPS. The ANS dye binding suggest that the exposure of HEWL tertiary structure is dependent on CHAPS concentration. As the concentrations of CHAPS is increasing the exposure of HEWL tertiary structure is also increasing and maximum exposure was found at 15.0 mM of CHAPS concentrations. The hydrodynamic radii of HEWL is also increase in the presence of sub-micellar and micellar concentrations of CHAPS because the tertiary structure of HEWL is disrupted. Overall, the results suggest that CHAPS is inducing secondary structure and disrupting tertiary structure of HEWL. This study provides detailed interaction of CHAPS with HEWL at the molecular level. [ABSTRACT FROM AUTHOR]

Abstract: For a mixed system of a typical membrane protein solubilizer CHAPS (a derivative of a bile acid cholic acid) combined with a bile salt (sodium salt of glycocholic acid, NaGC), which is also a candidate as a membrane protein solubilizer, micellization and adsorbed film formation in a phosphate buffer solution of pH 7.4 at 303K were studied paying special attention to the synergistic effect upon mixing. The collection of sufficient data based on plots of surface tension (γ) versus logarithmic concentration (C t or m t) in total molality at discrete mole fractions (X 2) in the mixture of surfactants 1 and 2 (where 1 and 2 correspond to CHAPS and NaGC, respectively) allowed us to accurately determine critical micelle concentration (CMC), minimum surface tension at CMC (γ CMC), and the slope (dγ/dln C t) from the γ–ln C t curves in the concentration range just below CMC. These data enabled us to estimate surface excess (Γ t), and mean molecular area (A m) in addition to such parameters as the minimum surface Gibbs energy (), pC 20 and CMC/C 20 related to synergism accompanied by blending. Applying the regular solution theory (RST), the relation of compositions of the singly dispersed phase (X 2) and the micellar phase (Y 2) as well as the interaction parameter (ω R) (by using the Rubingh''s equations) were estimated. The relation between the composition in the adsorbed film (Z 2) and X 2 together with the interaction parameter (ω A) in the adsorbed film was also estimated. The partial molecular area (PMA), γ CMC, and were examined as functions of X 2 and/or Z 2. The resultant CMC–X 2 and CMC–Y 2 curves and ω R and ω A values have demonstrated that mixed micelles and adsorbed film formation are attained accompanying to some extent enhanced intermolecular interaction (with negative ω R and ω A values). Comparing with previous results for mixed systems of CHAPS with n-acyl (octanoly, nonanoyl, and decanoyl)-N-methylglucamides [MEGA-n''s (n =8, 9, and 10)] and of sodium chenodeoxycholate (NaCDC) with sodium ursodeoxycholate (NaUDC), the synergism observed for the mixed system of CHAPS with NaGC lies between both combinations. However the expected properties as a membrane protein solubilizer are judged to be sufficient. [Copyright &y& Elsevier]

Two primary methods for reconstructing paleofire occurrence include dendrochronological dating of fire scars and stand ages from live or dead trees (extending back centuries into the past) and sedimentary records of charcoal particles from lakes and bogs, providing perspectives on fire history that can extend back for many thousands of years. Studies using both proxies have become more common in regions where lakes are present and fire frequencies are low, but are rare where high-frequency surface fires dominate and sedimentary deposits are primarily bogs and wetlands. Here we investigate sedimentary and fire-scar records of fire in two small watersheds in northern New Mexico, in settings recently characterised by relatively high-frequency fire where bogs and wetlands (Chihuahueflos Bog and Alamo Bog) are more common than lakes. Our research demonstrates that: (1) essential features of the sedimentary charcoal record can be reproduced between multiple cores within a bog deposit; (2) evidence from both fire scarred trees and charcoal deposits documents an anomalous lack of fire since 1900, compared with the remainder of the Holocene; (3) sedimentary charcoal records probably underestimate the recurrence of fire events at these high-frequency fire sites; and (4) the sedimentary records from these bogs are complicated by factors such as burning and oxidation of these organic deposits, diversity of vegetation patterns within watersheds, and potential bioturbation by ungulates. We consider a suite of particular challenges in developing and interpreting fire histories from bog and wetland settings in the Southwest. The identification of these issues and constraints with interpretation of sedimentary charcoal fire records does not diminish their essential utility in assessing millennial-scale patterns of fire activity in this dry part of North America. [ABSTRACT FROM AUTHOR]

Abstract: The serotonin1A receptor is an important member of the G-protein coupled receptor family, and is involved in a variety of cognitive, behavioral, and developmental functions. None of the subtypes of G-protein coupled serotonin receptors have yet been purified to homogeneity from natural sources. We report here, for the first time, the solubilization of human serotonin1A receptors stably expressed in neuronal (HN2) cells. Importantly, ligand binding assay shows that the serotonin1A receptor solubilized this way is functionally active. The effective solubilization of the serotonin1A receptor from neuronal cells represents an important step toward the purification of the receptor in native-like membrane environment. [Copyright &y& Elsevier]

Abstract: Regarding our previous report on refolding of alkaline phosphatase [Yazdanparast and Khodagholi, 2005 Arch. Biochem. Biophys] it was found that in spite of the anti-aggregatory effect of 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS), a zwitteronic detergent, the recovered activity was almost the same as the recovered activity obtained through the unassisted approach. The low recovery yield is probably due to the bulky groups of the detergent that interfere with its entrance into the small cavity of the stripping agent, cyclodextrin, implying that the stripping of detergent molecules from the detergent–protein complexes plays a major role in successful refolding processes. To improve the efficiency of CHAPS stripping, we evaluated, for the first time, the stripping potential of a molecular imprinting polymer designed to replace β-CD. In this approach, CHAPS was used as the template and the refolding of GuHCl denatured alkaline phosphatase was studied. Our results indicated that under the optimally developed refolding environment and similar to stripping by soluble β-CD, a refolding yield of 79% was obtained for denatured alkaline phosphatase using 20 mg/ml of the molecularly imprinted poly (β-CD) polymer. The major advantage of the new stripping agent, besides of its recycling option and ease of separation from the finished product, is its high potential of preventing aggregate formation. Based on these results, it seems that the new stripping strategy can constitute an ideal approach for refolding of proteins at much lower industrial costs compared to stripping with soluble β-cyclodextrin. [Copyright &y& Elsevier]

Abstract: Cloned EcR and USP cDNAs encoding the ecdysone receptors of four insect pests (Lucilia cuprina, Myzus persicae, Bemisia tabaci, Helicoverpa armigera) were manipulated to allow the co-expression of their ligand binding domains (LBDs) in insect cells using a baculovirus vector. Recombinant DE/F segment pairs (and additionally, for H. armigera, an E/F segment pair) from the EcR and USP proteins associated spontaneously with high affinity to form heterodimers that avidly bound an ecdysteroid ligand. This shows that neither ligand nor D-regions are essential for the formation of tightly associated and functional LBD heterodimers. Expression levels ranged up to 16.6mg of functional apo-LBD (i.e., unliganded LBD) heterodimer per liter of recombinant insect cell culture. Each recombinant heterodimer was affinity-purified via an oligo-histidine tag at the N-terminus of the EcR subunit, and could be purified further by ion exchange and/or gel filtration chromatography. The apo-LBD heterodimers appeared to be more easily inactivated than their ligand-containing counterparts: after purification, populations of the former were <40% active, whereas for the latter >70% could be obtained as the ligand–LBD heterodimer complex. Interestingly, we found that the amount of ligand bound by recombinant LBD heterodimer preparations could be enhanced by the non-denaturing detergent CHAPS (3-[(3-cholamidopropyl)dimethyl-ammonio]-1-propanesulfonate). Purity, integrity, size and charge data are reported for the recombinant proteins under native and denaturing conditions. Certain intra- and intermolecular disulfide bonds were observed to form in the absence of reducing agents, and thiol-specific alkylation was shown to suppress this phenomenon but to introduce microheterogeneity. [Copyright &y& Elsevier]

Abstract: Two isoforms of ryanodine receptors are expressed in skeletal muscles, RyR1 and RyR3. We investigated the relative level of expression of RyRs in developing murine skeletal muscles using [3H]ryanodine binding and immunoprecipitation experiments. In the diaphragm RyR3 accounted for 11% of total RyRs in 5-day-old mice and for 3% of total RyRs in 60-day-old mice. In hindlimb muscles, RyR3 accounted for 3% and 1% of total RyRs in 5-day-old and adult mice, respectively. The activity of RyR1 channels in native microsomal vesicles from murine muscles was found to be as low as 35% of that measured after CHAPS exposure, while no inhibition was observed for RyR3. CHAPS sensitivity of recombinant RyR1 and RyR3 expressed in HEK293 cells was also investigated. The activity of recombinant RyR1 but not RyR3 channels was found to be inhibited in native conditions, suggesting that this property may not be dependent on a muscle environment. [Copyright &y& Elsevier]

Protein extraction is the most important step to reveal a proteome by Two-Dimensional Gel Electrophoresis. Usually, the urea/thiourea based standard protein extraction buffer (SB) is combined with detergents with the aim of achieving better resolution and solubilization of different classes of proteins. In order to produce better gels and achieve the greatest spot resolution of Human Brain Proteins, comparisons using 2-DE of extracted proteins from Human Brain Frontal Cortex with SB constituents (7M Urea, 2M Thiourea and 100mM DTT) were made, using different detergent compositions in the buffer. SB preparations in combination with CHAPS and ASB-14 as well as with ASB- 16 (reported for the first time in 2-DE experiments) have been tested. Our results confirm that the most efficient solubilizing solution for 2-DE analysis of cytosolic and membrane Human Brain Proteins is SB combined with 4% CHAPS and 2% ASB-14. [ABSTRACT FROM AUTHOR]

Emulsification of aqueous protein solutions in methylene chloride triggered the formation of water-insoluble aggregates at a water/methylene chloride interface. As a result, the amounts of β-lactoglobulin and ovalbumin recovered in water were 36 and 44%, respectively. Addition of 5 m m CHAPS in the aqueous phase raised the degree of β-lactoglobulin recovery to 96%. Sodium taurocholate, however, failed to improve protein recovery. The stabilizing effect of CHAPS was also protein-specific and concentration-dependent: at ≥5 m m, the surfactant caused unfolding of ovalbumin to make a water-soluble oligomer. CHAPS thus stabilizes proteins at an interface. [ABSTRACT FROM AUTHOR]

In Saccharomyces cerevisiae, the synthesis of chitin is temporally and spatially regulated through the transport of Chs3p (chitin synthase III) to the plasma membrane in the bud neck region. Traffic of Chs3p from the trans-Golgi network (TGN)/early endosome to the plasma membrane requires the function of Chs5p and Chs6p. Chs6p belongs to a family of four proteins that we have named ChAPs for Chs5p-Arf1p-binding Proteins. Here, we show that all ChAPs physically interact not only with Chs5p but also with the small GTPase Arf1p. A short sequence at the C-terminus of the ChAPs is required for protein function and the ability to bind to Chs5p. Simultaneous disruption of two members, Δbud7 and Δbch1, phenocopies a Δchs6 or Δchs5 deletion with respect to Chs3p transport. Moreover, the ChAPs interact with each other and can form complexes. In addition, they are all at least partially localized to the TGN in a Chs5p-dependent manner. Most importantly, several ChAPs can interact physically with Chs3p. We propose that the ChAPs facilitate export of cargo out of the Golgi. [ABSTRACT FROM AUTHOR]

Aims: To evaluate an improved bioluminescent enzyme immunoassay (BEIA) using biotinylated firefly luciferase for the rapid detection of Salmonella in naturally contaminated chicken meat samples. Methods and Results: Capture agents and lipopolysaccharide (LPS) extraction reagents for Salmonella were investigated to improve the sensitivity of the BEIA. Also, the use of Oxoid SPRINT (Simple Pre-enrichment and Rapid Isolation New Technology) as a pre-enrichment and selective medium for 26-h BEIA detection of Salmonella in chicken meat samples was examined. The use of polymyxin B as a capture agent on solid support and 3-[(3-Cholamidopropyl) dimethylammonio] propanesulfonic acid (CHAPS) for extraction of the LPS facilitated sensitive detection of Salmonella. Of 120 chicken meat samples, 25 samples were positive using the improved BEIA with the SPRINT and 25 samples were positive using the SPRINT followed by the standard isolation methods. Conclusions: The improved BEIA, in which polymxin B was used as a capture agent and CHAPS was used for extraction of the antigen, had a sensitivity of 96·0% and a specificity of 98·9% for the detection of Salmonella in chicken meat. Significance and Impact of the Study: The improved BEIA combined with the SPRINT medium for the detection of Salmonella in chicken meat samples produced comparable results to the culture methods in 26 h. [ABSTRACT FROM AUTHOR]

Abstract: By means of surface tension measurement (Wilhelmy method), micellization and adsorbed film formation were investigated for three combinations of mixed surfactant systems, all of which are used for solubilizing membrane proteins: a typical zwitterionic surfactant, CHAPS (a derivative of cholic acid) with n-alkyl (octyl, nonyl and decyl)-N-glucamides, MEGA-n (n =8, 9, 10). The data based on plotting of surface tension (γ) versus logarithmic total molarity (or molality) (C t or M t) as a function of mole fraction of surfactant 2 (2 corresponds to MEGA-n''s) enabled us to determine critical micellization concentration (CMC), minimum surface tension at CMC (γ CMC), surface excess (Γ t), mean molecular surface area (A m), the minimum Gibbs energy () of adsorbed film of both single and mixed surfactant systems and partial molecular area (PMA) in addition to parameters such as pC 20 and CMC/C 20 being related to synergism accompanied by blending (mixing) in regard to surface activity as well as micelle forming ability. On the basis of the regular solution theory, the relations of compositions of singly dispersed phase (X 2), micellar phase (Y 2) and adsorbed film (Z 2) were estimated, and then the interaction parameters in micelles (ω R) and in the adsorbed film phase (ω A) were also calculated. From both the CMC–X 2 and CMC–Y 2 curves, it was found for all the combinations to show synergistically enhanced ability of mixed micelle formation as well as surface tension reduction. The resultant synergism coming from blending CHAPS with MEGA-n''s was discussed in comparison with different combinations of various types of surfactants including membrane proteins solubilizers. [Copyright &y& Elsevier]

Solubilization of integral membrane proteins is a process in which the proteins and lipids that are held together in native membranes are suitably dissociated in a buffered detergent solution. The controlled dissociation of the membrane results in formation of small protein and lipid clusters that remain dissolved in the aqueous solution. Effective solubilization and purification of membrane proteins, especially heterologously-expressed proteins in mammalian cells in culture, in functionally active forms represent important steps in understanding structure-function relationship of membrane proteins. In this review, critical factors determining functional solubilization of membrane proteins are highlighted with the solubilization of the serotonin1A receptor taken as a specific example. IUBMB Life, 57: 505–512, 2005 [ABSTRACT FROM AUTHOR]

Plasma membrane (PM) vesicles isolated from the yeast Saccharomyces cerevisiae (wild-type NCIM 3078, and a MG 21290 mutant pma 1-1) were used to monitor the effect of the detergents, 3-[(3-cholamidopropyl) dimethylammonio]-1-propane sulfonate (Chaps) and Triton X-100, on H + -ATPase (E.C. 3.6.1.35), NADH oxidase and NADH- hexacynoferrate (III)[HCF (III)] oxidoreductase (E.C. 1.6.99.3) activities. The results obtained show that Triton X-100 inhibited both membrane bound and solubilized NADH-dependent redox activities. The nature of this inhibition as determined for NADH–HCF(III) oxidoreductase was non-competitive and the Ki values for wild and mutant enzymes were 1.2?×?10 -5 ?M and 8.0?×?10 -6 ?M, respectively. The findings are interpreted, in view of the established reports, that the active site architecture of PM bound NADH-dependent oxidoreductase in yeast is likely to be different than in other eukaryotes. [ABSTRACT FROM AUTHOR]

We have recently reported the crystallization by reconstitution into lipid bilayer structures of Enzyme IICmtl, the transmembrane C-domain of the mannitol transporter from E. coli. The projected structure was determined to a resolution of 0.5 nm [J. Mol. Biol. 287 5 (1999) 845]. However, further investigation proved that these crystals were multilamellar stacks instead of 2D crystals, and therefore were unsuitable for three-dimensional structural analysis by electron crystallography. Understanding the crystallogenesis of these crystals could reveal the mechanism of formation of multilayers. In the present study, cryo-electron microscopy (cryo-EM) and turbidimetry are used to study the successive steps of reconstitution of Enzyme IICmtl into phospholipid-containing structures and its crystallization under different conditions. Our experimental approach enabled us to distinguish the separate steps of reconstitution and crystallization. The salt concentration especially influenced the nature of the vesicles, either half open unilamellar or aggregated multilamellar, formed during reconstitution of Enzyme IICmtl. The presence of DOPE and DOPC and the temperature influenced the type of lipid structures that were formed during the crystallization phase of Enzyme IICmtl. Cryo-EM showed that protein crystallization is closely associated with the formation of isotropic lipid (cubic) phases. We believe that DOPE is responsible for the formation of these lipid cubic phases, and that crystallization is driven by exclusion of protein from these phases and its concentration into the lamellar phases. This mechanism is inextricably associated with the formation of multilayers. [Copyright &y& Elsevier]

In antibody-based immunoassay, it is important to fabricate a structured base plate with high activity for antibody immobilization. To prevent the reduction of anti-LDL binding capacity due to protein G aggregation, detergent was introduced to control the size of protein G aggregate. The self-assembled monolayer of 11-mercaptoundecanoic acid (11-(MUA)) and hexanethiol mixture was fabricated to form the stable protein G layer. 3-[(cholamidopropyl)dimethyl-ammonio]-1-propane sulfonate (CHAPS) was used for the regulation of protein G aggregate immobilized on the 11-(MUA) surface. The effect of various CHAPS concentrations on the amount of anti-low density lipoprotein (LDL) immobilized on protein G layer was investigated. Twelve millimolars of CHAPS were determined as the optimal concentration to maximize the binding capacity of anti-LDL due to the control of protein G density on the surface. The anti-LDL layer on self-assembled protein G using CHAPS was applied to surface plasmon resonance immunosensor for detection of LDL and its detection limit was 100 pM. [Copyright &y& Elsevier]

The self-assembled ferredoxin monolayer onto the (100) surface of the silicon substrate was prepared and the nonspecifically adsorbed aggregates of ferredoxin on the substrate were successfully eliminated by using a zwitterionic surfactant, 3-[(3-cholamidopropyl) dimethylammonio]-1-propanesulfonate (CHAPS). The AFM image of the self-assembled ferredoxin monolayer on the silicon substrate treated with CHAPS clearly shows that the size of ferredoxin clusters is about 20–30 nm, which is on the order of an aggregate of about five ferredoxin molecules, whereas the size of ferredoxin aggregates on the substrate without CHAPS treatment was measured to be about 100–200 nm. Those results offer a useful method for the elimination of the nonspecific adsorption of proteins onto inorganic substrates, which has been a long-term problem in the fabrication of biomolecular electronic devices by the self-assembly technique. [Copyright &y& Elsevier]

The serotonin[sub 1A] (5-HT[sub 1A]) receptors are members of a superfamily of seven transmembrane domain receptors that couple to G-proteins. They appear to be involved in various behavioural and cognitive functions. This paper reports an efficient strategy to solubilize 5-HT[sub 1A] receptors from bovine hippocampal membranes using the zwitterionic detergent CHAPS which is mild and non-denaturing. Since high concentration of CHAPS has earlier been shown to induce dissociation and depletion of G-protein sub-units, a low (pre-micellar) concentration of CHAPS was used for solubilizing 5-HT[sub 1A] receptors in the presence of NaCl followed by PEG precipitation. This results in solubilization of 5-HT[sub 1A] receptors with a high degree of efficiency and gives rise to high affinity, functionally active G-protein-sensitive solubilized receptors. Optimal solubilization of the receptor from the native source with high ligand binding affinity and intact signal transduction components may constitute the first step in the molecular characterization of the 5-HT[sub 1A] receptor in particular, and G-protein-coupled receptors in general. [ABSTRACT FROM AUTHOR]