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An ideal carbon-based supercapacitor electrode requires abundant micropores that are favorable for charge accumulation, and suitable mesopores that are beneficial for fast electrolyte ions transport. Herein, 3D porous carbon microspheres (carbon nanotube-ketjen black/activated carbon, CNT-KB/AC), where the CNT-KB microspheres (CKMS) as the framework providing mesopores and the activated carbon as the core providing micropores, have been constructed by spray drying and KOH activation. The obtained carbon composites exhibit a homogeneous spherical structure and high specific surface area (up to 1751 m2 g−1). The CNT-KB/AC electrode with an areal density of 3 mg cm−2 can achieve a high areal capacitance of 506.9 mF cm−2 at the current density of 0.2 A g−1 in 6 M KOH solution, which is much larger than that of the CNT/AC electrode (232.6 mF cm−2) and CNT-AB/AC electrode (179.5 mF cm−2). Besides, when the areal density is increased up to 9 mg cm−2, the areal capacitance of CNT-KB/AC is increased up to 998.9 mF cm−2 at 0.2 A g−1 and 724.9 mF cm−2 at 20 A g−1. Furthermore, it exhibits excellent long-term cycling stability (achieving capacitance retention of 94% after 10,000 cycles). These results indicate that the CNT-KB/AC composites are promising electrode materials for high-areal-density supercapacitors.

An ultrafine (6–7 nm) and well dispersed nano-SnO2/carbon nanotube hairball (SnO2/CNTH) composite material with a three-dimensional (3D) hierarchical structure is prepared by spray drying and solvo...

Inclusion of polymer additives is a known strategy to improve foam stability, but questions persist about the amount of polymer incorporated in the foam and the resulting structural changes that impact material performance. Here, we study these questions in sodium dodecyl sulfate (SDS)/hydroxypropyl methylcellulose (HPMC) foams using a combination of flow injection QTOF mass spectrometry and small-angle neutron scattering (SANS) measurements leveraging contrast matching. Mass spectrometry results demonstrate polymer incorporation and retention in the foam during drainage by measuring the HPMC-to-SDS ratio. The results confirm a ratio matching the parent solution and stability over the time of our measurements. The SANS measurements leverage precise contrast matching to reveal detailed descriptions of the micellar structure (size, shape, and aggregation number) along with the foam film thickness. The presence of HPMC leads to thicker films, correlating with increased foam stability over the first 15-20 min after foam production. Taken together, mass spectrometry and SANS present a structural and compositional picture of SDS/HPMC foams and an approach amenable to systematic study for foams, gathering mechanistic insights and providing formulation guidance for rational foam design.

Objective Patients with cardiac surgery–associated acute kidney injury are at risk of renal replacement therapy and in-hospital death. We aimed to develop and validate a novel predictive model for poor in-hospital outcomes among patients with cardiac surgery–associated acute kidney injury. Methods A total of 196 patients diagnosed with cardiac surgery–associated acute kidney injury were enrolled in this study as the training cohort, and 32 blood cytokines were measured. Least absolute shrinkage and selection operator regression and random forest quantile-classifier were performed to identify the key blood predictors for in-hospital composite outcomes (requiring renal replacement therapy or in-hospital death). The logistic regression model incorporating the selected predictors was validated internally using bootstrapping and externally in an independent cohort (n = 52). Results A change in serum creatinine (delta serum creatinine) and interleukin 16 and interleukin 8 were selected as key predictors for composite outcomes. The logistic regression model incorporating interleukin 16, interleukin 8, and delta serum creatinine yielded the optimal performance, with decent discrimination (area under the receiver operating characteristic curve: 0.947; area under the precision-recall curve: 0.809) and excellent calibration (Brier score: 0.056, Hosmer–Lemeshow test P = .651). Application of the model in the validation cohort yielded good discrimination. A nomogram was generated for clinical use, and decision curve analysis demonstrated that the new model adds more net benefit than delta serum creatinine. Conclusions We developed and validated a promising predictive model for in-hospital composite outcomes among patients with cardiac surgery–associated acute kidney injury and demonstrated interleukin-16 and interleukin-8 as useful predictors to improve risk stratification for poor in-hospital outcomes among those with cardiac surgery–associated acute kidney injury.

MicroRNAs, a class of small and non-encoding RNAs that transcriptionally or post-transcriptionally modulate the expression of their target genes, have been implicated as critical regulatory molecules in ischemia-/reperfusion-induced cardiac injury. In the present study, we report on the role of miR-208a in myocardial I/R injury and the underlying cardio-protective mechanism. The gain-of-function and loss-of-function were used to explore the effects of miR-208a on cardiac injury induced by H2O2 in cardiomyocytes. As predicted, knockdown of endogenous miR-208a significantly decreased the level of cellular reactive oxygen species (ROS) and reduced cardiomyocyte apoptosis. In addition, miR-208a overexpression increased the ROS level and attenuated cell apoptosis in cardiomyocytes. Furthermore, protein tyrosine phosphatase receptor type G (PTPRG) and protein tyrosine phosphatase, non-receptor type 4 (PTPN4), which participate in regulating the level of cellular protein tyrosine phosphorylation balance, were predicted and verified as potential miR-208a targets using bioinformatics and luciferase assay. In summary, this study demonstrated that miR-208a plays a critical protective role in ROS-induced cardiac apoptosis.

EPR spectroscopy was used to monitor formation of free radicals in human hair upon UV irradiation. While the EPR spectra of brown hair were dominated by melanin signal, those of white hair were keratin-derived. The decay of UV induced keratin radicals was enhanced at increased ambient humidity. We argue that at higher humidity the swollen hair provides a more liquid-like environment, and higher molecular mobility in this environment leads to faster radical reactions. This interpretation is consistent with the increased UV-triggered protein damage in hair at high humidity as demonstrated by the protein loss, MALDI-TOF and FT-IR data.

In this work, switchable hydrophilicity solvent-based ultrasound-assisted liquid phase microextraction (SHS-UA-LPME) was combined with micro-volume UV-vis spectrophotometry for the determination of trace nickel in the medicinal plant Gentiana rigescens Franch. ex Hemsl. (G. rigescens) samples for the first time. Micro-volume spectrophotometry has the characteristics of microanalysis, economy and low operation cost, which is feasible to be combined with miniaturized enrichment method. Dipropylamine (DPA) as a switchable solvent completed the extraction during the phase conversion process. It was changed from hydrophobic to hydrophilic under the action of HCl, and then completed phase transition under the action of NaOH. The parameters influencing the extraction efficiency were investigated. Under the optimal conditions, the enhancement factor (EF), the limit of detection (LOD), the limit of quantitation (LOQ) and relative standard deviation (RSD, n = 7) were 28, 0.02 µg/L, 0.067 µg/L and 1.4%, respectively. The established method was applied to the determination of G. rigescens samples collected from the local field with satisfactory results.

There is a need to investigate the role of nuclear factor kappa B in the regulation of cyclooxygenase-2 expression in the epileptic rat brain and cultured hippocampal neurons. Immunofluorescence and polymerase chain reaction was used to detect the expression of nuclear factor kappa B and cyclooxygenase-2. In cultured hippocampal neurons and rat brain: the control group compared with the normal group, nuclear factor kappa B expression in the hippocampal dentate gyrus, cerebral cortex, the piriform cortex brain regions were significantly increased (P < 0.01). This is accompanied by a significant increase in cyclooxygenase-2 protein and mRNA expressions in the hippocampus (P < 0.01). In the experimental group compared to the control group, the nuclear factor-kappa B expression in the hippocampal dentate gyrus, cerebral cortex, piriform cortex, and other brain regions was significantly lower (P < 0.01), with the accompanying decrease in cyclooxygenase-2 protein and mRNA expression (P < 0.01) in the hippocampus. In conclusion, κB-decoy can inhibit nuclear factor kappa B activation in epileptic rat brain and cyclooxygenase-2 overexpression.

Chondroitin sulfate (CS) and dermatan sulfate (DS) proteoglycans (PGs) are major extracellular matrix (ECM) components of the central nervous system (CNS). A large body of evidence has shown that CSPGs/DSPGs play critical roles in neuronal growth, axon guidance, and plasticity in the developing and mature CNS. It has been proposed that these PGs exert their function through specific interaction of CS/DS chains with its binding partners in a manner that depends on the sulfation patterns of CS/DS. It has been reported that dermatan 4-O-sulfotransferase-1 (Chst14/D4st1) specific for DS, but not chondroitin 4-O-sulfotransferase-1 (Chst11/C4st1) specific for CS, regulates proliferation and neurogenesis of neural stem cells (NSCs), indicating that CS and DS play distinct roles in the self-renewal and differentiation of NSCs. However, it remains unknown whether specific sulfation profiles of DS has any effect on CNS plasticity. In the present study, Chst14/D4st1-deficient (Chst14−/−) mice was employed to investigate the involvement of DS in synaptic plasticity. First, behavior study using Morris Water Maze (MWM) showed that the spatial learning and memory of Chst14−/− mice was impaired when compared to their wild type (WT) littermates. Corroborating the behavior result, long-term potentiation (LTP) at the hippocampal CA3-CA1 connection was reduced in Chst14−/− mice compared to the WT mice. Finally, the protein levels of N-Methyl-D-aspartate (NMDA) receptor, α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) receptor, postsynaptic density 95 (PSD95), growth associated protein 43 (GAP-43), synaptophysin (SYN) and N-ethylmaleimide sensitive factor (NSF) which are important in synaptic plasticity were examined and Chst14/D4st1 deficiency was shown to significantly reduce the expression of these proteins in the hippocampus. Further studies revealed that Akt/mammalian target rapamycin (mTOR) pathway proteins, including protein kinase B (p-Akt), p-mTOR and p-S6, were significantly lower in Chst14−/− mice, which might contribute to the decreased protein expression. Together, this study reveals that specific sulfation of DS is critical in synaptic plasticity of the hippocampus and learning and memory, which might be associated with the changes in the expression of glutamate receptors and other synaptic proteins though Akt/mTOR pathway.

Two novel aggregation-induced emission (AIE) based fluorescent probes, TPANI-DNs and PCZNI-DNs, have been designed and synthesized for “turn-on” detection of H2S. Chromophore napthalimide fused triphenylamine (or phenylcarbazole) unit as fluorophore in combination with 2,4-dinitrobenzenesulfonyl as recognition moiety constructed probes. The design strategy of the twisted D-π-A structure can efficiently transform the aggregation-caused quenching (ACQ) system into the AIE system by strengthening the restriction of intramolecular motion and preventing the intermolecular π-π stacking. The consequences showed that both TPANI-DNs and PCZNI-DNs displayed large stokes shift (135 nm and 120 nm, respectively), high selective and sensitive detection. The response mechanisms and fluorescent properties were further investigated through the time-dependent density functional theory (TDDFT). Importantly, since the strong AIE properties, a H2S test board has been prepared and used to detect H2S onsite easily and sensitively, displaying potential practical applications.

Surface coating is an efficient strategy to enhance the interfacial stability of the electrode. Graphene quantum dots (GQDs) have advantages of excellent dispersion in water, outstanding electron and ion conductivities and high specific surface area. In this work, GQDs were coated directly on the surface of LiCoO2 particles (GQDs-LiCoO2) through liquid phase method. Compared to bare LiCoO2, the cycling performance, rate capacity and thermo-stability of the GQDs-LiCoO2 have been significantly improved in the voltage range of 3.04.5 V. GQDs-LiCoO2 showed a much higher capacity retention than that of bare LiCoO2 (82.8 % vs 46.1 %) after 100 cycles at 0.5 C. The excellent improvement of the GQDs-LiCoO2 was mainly attributed to the formation of a uniform, stable, dense and well-conductive protective layer on the surface of LiCoO2 particles by the surface coating of GQDs. The detailed analysis of the cycled electrodes reveals that the GQDs coating stabilizes the crystal structure of LiCoO2 and suppresses undesirable interfacial side reactions between the cathode and electrolyte, leading to the improvement of battery performance.

Genipin is the major active component of Gardeniae fructus and has been shown to ameliorate diabetes and insulin resistance in rat models. In this study, we first investigated the effect of genipin on obesity and the related lipid metabolism mechanisms in diet-induced obese rats. Our results showed that genipin reduced body weight, food intake, and visceral fat mass; ameliorated dyslipidemia, glucose intolerance, insulin intolerance, adipocyte hypertrophy, and hepatic steatosis; and reduced serum tumor necrosis factor-α level in diet-induced obese rats. Quantitative real-time reverse-transcription polymerase chain reaction results further illustrated that genipin promoted lipolysis and β-oxidation of fatty acid by upregulating gene expressions of hormone-sensitive lipase and adipose triglyceride lipase in white adipose tissue (WAT) and peroxisome proliferator-activated receptor-α and carnitine palmitoyltransferase 1α in hepatic tissue. Moreover, genipin promoted browning of WAT by upregulating the mRNA and protein levels of uncoupling protein 1 and PRD1-BF1-RIZ1 homologous domain containing 16 in WAT. Additionally, genipin inhibited gene expressions of activin receptor-like kinase 7, tumor necrosis factor-α, and interlukin-6 in WAT. These results indicated that genipin had a potential therapeutic role in obesity, in which regulation of lipid mobilization and browning of WAT were involved.

The protective effects of dioscin, a natural steroidal saponin from some medicinal plants including Dioscorea nipponica Makino, against lipopolysaccharide (LPS)- induced acute liver and renal damages have been reported in our previous works. However, its effect on LPS-induced acute lung injury (ALI) remains unknown. In the present study, the effects and possible mechanisms of dioscin against LPS-induced ALI in vitro and in vivo were investigated. The results showed that dioscin effectively inhibited cell proliferation and markedly decreased reactive oxidative species (ROS) level in 16HBE cells treated by LPS. In addition, dioscin significantly attenuated LPS-induced histological alterations, suppressed the infiltration of inflammatory cells, as well as decreased the levels of MDA, SOD, NO and iNOS in mice and rats (p < 0.05). Mechanistically, dioscin significantly decreased the protein levels of TLR4, MyD88, TRAF6, TKB1, TRAF3, phosphorylation levels of PI3K, Akt, IκBα, NF-κB, and the mRNA levels of IL-1β, IL-6 and TNF-α against oxidative stress and inflammation (p < 0.05). TLR4 overexpression was also decreased by dioscin, leading to the markedly decreased the levels of MyD88, TRAF6, TKB1, TRAF3, p-PI3K, p-Akt, p-IκBα and p-NF-κB. These findings provide new insights that dioscin exhibited protective effect against LPS-induced ALI via adjusting TLR4/MyD88- mediated oxidative stress and inflammation, which should be developed as one potent candidate for the treatment of ALI in the future.

SynopsisObjective The objective of this work was to identify whether low levels of redox metals such as copper will accelerate damage to hair on exposure to UV irradiation and whether this damage can be prevented. Methods The methods used were proteomics to measure the protein damage via protein loss after different periods of exposure and mass spectroscopy methods to identify specific marker peptides that are specifically created by this type of damage. Results In this work, we have developed new insights into the mechanism of UV damage using these proteomic methods. A marker fragment in the hair protein loss extract was identified (m/z = 1279) that is unique to UV exposure and increases with time of UV exposure. We have also identified for the first time in hair the role of exogenous copper in increasing UV damage both in terms of total protein degradation and also increased formation of the marker fragment and proposed a mechanism of action. It has been demonstrated that shampoo treatment containing a chelant such as N,N'-ethylenediamine disuccinic acid (EDDS) reduced copper accumulation in hair. Conclusion This work provides evidence for the role of copper in UV-induced damage to hair and strategies to reduce copper levels in hair using a chelant such as EDDS.

Introduction Ataluren functions by interacting with ribosomes to promote read-through of nonsense mutations in CF. Ataluren9s activity was shown to be inhibited by certain aminoglycosides such as tobramycin that also bind to the ribosome. Aim To investigate the effect of ataluren on lung function (LF) and pulmonary exacerbations. Methods A post-hoc analysis was performed on a recent randomized, double-blind, placebo-controlled, phase 3 study to determine the efficacy and safety of ataluren in patients with nonsense mutation cystic fibrosis (nmCF) (Kerem E, et al. Lancet Respir Med. 2014;2:539-47) on %-predicted FEV 1 (ppFEV 1 ) and exacerbations by use of chronic inhaled tobramycin at baseline. Results Patients not receiving chronic inhaled tobramycin (non-TOBI; n=146), showed a 5.7% difference in relative ppFEV 1 between ataluren and placebo (−0.7% vs −6.4%; p=0.0082) and 40% fewer exacerbations (1.42 vs 2.18; p=0.0061). Non-TOBI patients ≥6 to 1 between ataluren and placebo (4.9% vs −3.3%; p=0.026) and a 60% lower exacerbation rate favoring ataluren (p=0.030). In all intent-to-treat patients (N=232) at week 48, including tobramycin patients, neither relative change from baseline in ppFEV 1 (−2.5% vs −5.5%; p=0.12), nor number of exacerbations (1.42 vs 1.78; p=0.099) significantly differed between ataluren and placebo. Conclusions Ataluren significantly reduced exacerbations and improved LF in nmCF patients not receiving chronic inhaled tobramycin, with markedly improved treatment effect in children and adolescents. Ataluren thus shows promise as a disease-modifying therapy in nmCF.

Background Myocardial infarction (MI) remains the most common cause of heart failure (HF) worldwide. For almost 50 years, HF has been recognized as a determinant of adverse prognosis after MI, but efforts to promote myocardial repair have failed to be translated into clinical therapies. Aims In this study, we investigated the effects of BRD4 on cardiac function and the underlying mechanism. Material and methods The in vivo rat model of AMI and in vitro neonatal cardiomyocytes were established and cultured respectively, the BRD4 and NPPA/NPPB expression levels were detected by qPCR and Western blot, and interaction of BRD4 with acetylation RelA or NPPA/B promoters were examined by co-immunoprecipitation and chromatin immunoprecipitation assays, respectively. Results We found that BRD4 protein expression was significantly increased in cardiomyocytes of MI rat model and cardiomyocytes under hypoxia, accompanied by the expression of natriuretic peptide A (NPPA) and natriuretic peptide B (NPPB). Functionally, knockdown of BRD4 greatly downregulated the NPPA and NPPB in vivo and in vitro, improved the hemodynamic and biometric parameters in rat with heart failure, as well as decreased the apoptosis occurrence. In vitro studies further demonstrated that BRD4 bound with acetylated RelA to enhance the activation of NF-κb signaling, which resulted in activation of NPPA and NPPB transcriptions. Conclusions Taken together, our findings suggest that inhibition of BRD4 attenuated cardiomyocyte apoptosis via NF-κB pathway in myocardial infarction, and this study sheds light on developing new strategies to overcome myocardial damage.

Introduction Social isolation enhances the aggressive behavior of animals, but the detailed mechanism remains unclear. Epigenetic studies have suggested that Htr2c RNA editing is closely related to aggressive behavior. This study aims to obtain a fundamental understanding of how social isolation impacts adenosine deaminase acting on RNA 1 (ADAR1, RNA editing enzyme) and Htr2c RNA editing, leading to aggressive behavior, and explore the effective solutions for the recovery of this behavior. Methods We evaluated 21-day-old BALB/c mice with and without isolation for aggressive behavior using a resident-intruder test. Immune-reactivity and protein expression of ADAR1 (p110) were measured using immunohistochemistry and Western blotting. Htr2c RNA editing was evaluated using pyrosequencing. In addition, the 5-HT 2C R antagonist SB243213/5-HT 2C R inverse agonist SB206553 was used to treat the isolated mice, and the performance of both treatments on the behavior, ADAR1 (p110) expression, and Htr2c RNA editing in isolated mice was examined. Results Both the protein expression and immune-reactivity of ADAR1 (p110) in the amygdala decreased, but the percentage of Htr2c RNA editing at A and B sites of amygdala only showed a moderate increase in isolated BALB/c mice with enhanced aggressive behavior compared to the age-matched group-housed BALB/c mice. Additionally, treatment with the 5-HT 2C R antagonist SB243213/5-HT 2C R inverse agonist SB206553 recovered the enhanced aggressive behavior of isolated mice and returned the protein expression and immune-reactivity of ADAR1 (p110) back to the normal level. Moreover, compared to the age-matched isolated mice treated with physiological saline, isolated mice treated with 5-HT 2C R inverse agonist SB206553 showed a lower percentage of Htr2c RNA editing at both A and B sites, and the same result occurred in isolated mice treated with 5-HT 2C R antagonist SB243213 at B site of Htr2c RNA editing. Conclusions The 5-HT 2C R antagonist SB243213/5-HT 2C R inverse agonist SB206553 recovered increased aggressive behavior of isolated BALB/c mice mediated by ADAR1 (p110) expression and Htr2c RNA editing.

This study aimed to investigate the protective effect of nicotine on dopaminergic neurons and its mechanisms in mice with Parkinson disease (PD) induced by 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP). C57BL/6J mice were injected with MPTP for 8 days to establish a PD model. Nicotine was given for 10 days in the nicotine therapeutic group. Animals were examined behaviorally with the pole test and traction test. Tyrosine hydroxylase (TH) and γ-aminobutyric acid (GABA) were determined by using the immunocytochemistry (ICC) method. The ultrastructural changes of the caudate nucleus (CN) were observed under electron microscopy. The results showed that pretreatment with nicotine could improve the dyskinesia of PD mice markedly. Simultaneously, TH-positive (P

The competitive adsorption of the Na salt of phytic acid (PA) and 4-methyl-4H-1,2,4-triazole-3-thiol (4-MTTL) was investigated by using the surface-enhanced Raman scattering (SERS) technique and electrochemical measurements. On the basis of the recorded SERS spectra, it was found that PA molecules could competitively occupy the silver surface modified with 4-MTTL monolayers and that the competitive adsorption of 4-MTTL at the silver surface with the PA monolayers also happened, but the effect of coadsorption of PA on the structure of 4-MTTL monolayers was smaller than that of 4-MTTL on the PA monolayers. In addition, according to the electrochemical measurements, the only 4-MTTL monolayers or the only PA monolayers at the silver surface exhibited a reasonable stability. The coadsorption of 4-MTTL and PA formed a mixed film at the silver surface immersed in the solution with the coexistence of 4-MTTL and PA, and the film was unstable when a potential was applied.

Monolayers of sulfanilamide on metallic surface can serve as an ideal model for understanding the interaction mechanism between the metal and the sulfanilamide molecule. In the present paper, the surface-enhanced Raman scattering (SERS) technique was employed to obtain the SERS spectra of sulfanilamide monolayers formed on the silver surface under different pH values. Assignments of the spectra were carried out with the aid of density functional theory (DFT) calculations (BLYP/6-311G). It can be found that the adsorption function of sulfanilamide on the silver surface was influenced by the pH value. The fully protonated sulfanilamide molecule adsorbed on the silver surface through N13H2 group and the benzene ring anchored in a relatively perpendicular manner leading to N7H2 and S10O2 groups near the surface, while the completely deprotonated sulfanilamide molecule attached on the silver surface via N7H2 and the benzene ring was perpendicular to, and the N13H2 and S10O2 groups were far from the silver surface. Copyright © 2009 John Wiley & Sons, Ltd.

Electrochemically anticorrosive behavior of 4-methyl-4H-1,2, 4-triazole-3-thiol (MTTL) self-assembled monolayers (SAMs) on the silver electrode was studied by means of electrochemical impedance spectroscopy (EIS) and polarization measurements. The promising inhibition effect of the MTTL for silver had been affirmed. Results of surface-enhanced Raman scattering (SERS) experiments indicated that the MTTL molecule in a tilted orientation was self-assembled on the silver surface through S' and N(2) atoms to form monolayers. An in situ electrochemical SERS experiment implied the changes of adsorption fashion of MTTL momolayers on the silver surface with the potential shifted to more negative direction. Copyright (C) 2009 John Wiley & Sons, Ltd.

The pH-dependent structures of the 2-amino-5-mercapto-1,3,4-thiadiazole (AMT) self-assembled monolayers (SAMs) on the silver surface were studied by surface enhanced Raman scattering (SERS) spectroscopy. The resulting SERS spectra show that the adsorption fashion of AMT monolayers formed at pH 1 could exhibit the strongest interaction with the silver surface among the investigated pH values at 1, 7, and 13. Electrochemical impedance spectroscopy (EIS) illuminates that the anticorrosive effect of AMT monolayers formed under pH 1 is the best. The inhibition efficiencies of AMT SAMs formed under pH 1, 7 and 13 are 72.2, 39.1 and 4.97%, respectively, according to experimental results of their Tafel plots.

Anticorrosive behaviors of 2-mercaptobenzothiazole (MBT) self-assembled monolayers (SAMs) on silver and zinc electrodes were comparatively studied by means of electrochemical impedance spectroscopy (EIS). The promising inhibition effect of the MBT for silver and zinc from corrosion had been confirmed. The adsorption geometries of MBT monolayers on zinc and silver electrodes were observed by surface enhanced Raman scattering (SERS) technique. The SERS spectra implied that monolayers of MBT could be self-assembled on Ag surface through S 10 and N 3 atoms and the molecular plane should be tilted with respect to the surface. On Zn surface, MBT molecules formed monolayers via both S atoms and the other moieties of the molecule away from the surface. From the in situ electrochemical SERS results it can be found that MBT monolayers on both Ag and Zn surfaces experienced the changes of adsorption fashions as the potential shifting to more negative direction.

Surface-enhanced Raman scattering (SERS) spectroscopy was applied to observe the process and structure of N-acetylalanine molecules self-assembled at the silver surface. SERS data show that the N-acetylalanine molecules adsorb at the silver surface through the amino group and the entire carboxyl group in a perpendicular way after a self-reorganization. Results of SERS and X-ray photoelectron spectroscopic experiments indicate that the Ce3+ affects the structure of monolayers because of the binding reaction between the Ce3+ and the carbonyl along with the amino groups in N-acetylalanine. The Ce3+ capped by N-acetylalanine monolayers can be removed by adding EDTA solution and the original structure of monolayers is recovered. However, the impact of K+ on the structure of N-acetylalanine monolayers is slight and can be ignored.

SynopsisObjective Damage to hair from UV exposure has been well reported in the literature and is known to be a highly complex process involving initiation via absorption of UV light followed by formation and propagation of reactive oxygen species (ROS). The objective of this work was to understand these mechanisms, explain the role of copper in accelerating the formation of ROS and identify strategies to reduce the hair damage caused by these reactive species. Methods The location of copper in hair was measured by Transmission electron microscopy–(TEM) X-ray energy dispersive spectroscopy (XEDS) and levels measured by ICP-OES. Protein changes were measured as total protein loss via the Lowry assay, and MALDI ToF was used to identify the biomarker protein fragments. TBARS assay was used to measure lipid peroxide formation. Sensory methods and dry combing friction were used to measure hair damage due to copper and UV exposure and to demonstrate the efficacy of N,N' ethylenediamine disuccinic acid (EDDS) and histidine chelants to reduce this damage. Results In this work, a biomarker protein fragment formed during UV exposure is identified using mass spectrometry. This fragment originates from the calcium-binding protein S100A3. Also shown is the accelerated formation of this peptide fragment in hair containing low levels of copper absorbed from hair during washing with tap water containing copper ions. Transmission electron microscopy (TEM) X-ray energy dispersive spectroscopy (XEDS) studies indicate copper is located in the sulphur-poor endo-cuticle region, a region where the S100A3 protein is concentrated. A mechanism for formation of this peptide fragment is proposed in addition to the possible role of lipids in UV oxidation. A shampoo and conditioner containing chelants (EDDS in shampoo and histidine in conditioner) is shown to reduce copper uptake from tap water and reduce protein loss and formation of S100A3 protein fragment. In addition, the long-term consequences of UV oxidation and additional damage induced by copper are illustrated in a four-month wear study where hair was treated with a consumer relevant protocol of hair colouring treatments, UV exposure and regular shampoo and conditioning. Conclusions The role of copper in accelerating UV damage to hair has been demonstrated as well as the ability of chelants such as EDDS and histidine in shampoo and conditioner products to reduce this damage.

Protein protease inhibitors could potentially be used to stabilize proteases in commercial products such as liquid laundry detergents. However, many protein protease inhibitors are susceptible to hydrolysis inflicted by the protease. We have engineered Streptomyces subtilisin inhibitor (SSI) to resist proteolysis by adding an interchain disulfide bond and removing a subtilisin cleavage site at leucine 63. When these stabilizing changes were combined with changes to optimize the affinity for subtilisin, the resulting inhibitor provided complete protease stability for at least 5 months at 31 degrees C in a subtilisin-containing liquid laundry detergent and allowed full recovery of the subtilisin activity upon the dilution that occurs in a North American washing machine.

The Kaposi's sarcoma-associated herpesvirus (KSHV) encodes a FADD-like interferon converting enzyme or caspase 8 (FLICE) inhibitory protein (vFLIP) that prevents death receptor-mediated apoptosis by inhibiting the recruitment and activation of FLICE. Since vFLIP physically interacts with tumor necrosis factor receptor associated factor 2 (TRAF2) and TRAF2 mediates activation of the jun NH(2)-terminal kinase (JNK)/activation protein 1 (AP1) pathway, we hypothesized that vFLIP might also activate this pathway. To evaluate this hypothesis, we transiently and stably transfected a vFLIP expression construct and performed several complementary assays to document that vFLIP activates the JNK/AP1 pathway and does so in a TRAF-dependent fashion. As vFLIP also activates the nuclear factor kappaB (NF-kappaB) signaling pathway and the NF-kappaB and JNK/AP1 pathways both modulate cellular interleukin-6 (cIL-6) expression, we postulated that vFLIP induces expression of this cytokine. We show that vFLIP induces cIL-6 expression and activates the cIL-6 promoter, and maximal activation of the cIL-6 promoter by vFLIP requires NF-kappaB and AP1 activation. In addition, vFLIP and latency-associated nuclear antigen (LANA), another KSHV-encoded latent protein, potentiate each other's ability to activate the cIL-6 promoter. Gene silencing experiments by RNA interference demonstrate that vFLIP in BCBL-1 endogenously infected primary effusion lymphoma (PEL) cells mediates JNK/AP1 activation and cIL-6 expression. Thus, we conclude that vFLIP, in addition to its known effects on NF-kappaB activation, also modulates the JNK/AP1 pathway and induces gene expression from the cIL-6 promoter in a JNK/AP1-dependent fashion.

Kinetic interactions of β-lactam antibiotics such as penicillin-G and cefotaxime with normal, penicillin-susceptible PBP2x from Streptococcus pneumoniae and a penicillin-resistant PBP2x (PBP2xR) from a resistant clinical isolate (CS109) of the bacterium have been extensively characterized using electrospray mass spectrometry coupled with a fast reaction (quench flow) technique. Kinetic evidence for a two-step acylation of PBP2x by penicillin-G has been demonstrated, and the dissociation constant, K d of 0.9 mm, and the acylation rate constant, k 2 of 180 s−1, have been determined for the first time. The millimolar range K d implies that the β-lactam fits to the active site pocket of the penicillin-sensitive PBP rather poorly, whereas the extremely fast k 2 value indicates that this step contributes most of the binding affinity of the β-lactam. The values of K d (4 mm) and k 2 (0.56 s−1) were also determined for PBP2xR. The combined value ofk 2/K d, known as overall binding efficiency, for PBP2xR (137m −1 s−1) was over 1000-fold slower than that for PBP2x (200,000 m −1s−1), indicating that a major part is played by the acylation steps in penicillin resistance. Most of the decreased binding efficiency of PBP2xR comes from the decreased (∼300-fold)k 2. Kinetic studies of cefotaxime acylation of the two PBP2x proteins confirmed all of the above findings. Deacylation rate constants (k 3) for the third step of the interactions were determined to be 8 × 10−6s−1 for penicilloyl-PBP2x and 5.7 × 10−4 s−1 for penicilloyl-PBP2xR, corresponding to over 70-fold increase of the deacylation rate for the resistant PBP2xR. Similarly, over 80-fold enhancement of the deacylation rate was found for cefotaxime-PBP2xRcomplex (k 3 = 3 × 10−4s−1) as compared with that of cefotaxime-PBP2x complex (3.5 × 10−6 s−1). This is the first time that such a significant increase ofk 3 values was found for a β-lactam-resistant penicillin-binding protein. These data indicate that the deacylation step also plays a role, which is much more important than previously thought, in PBP2xR resistance to β-lactams.

Optimized procedures have been developed for the addition of sulfonic acid groups to the N-termini of low-level peptides. These procedures have been applied to peptides produced by tryptic digestion of proteins that have been separated by two-dimensional (2-D) gel electrophoresis. The derivatized peptides were sequenced using matrix-assisted laser desorption/ionization (MALDI) post-source decay (PSD) and electrospray ionization-tandem mass spectrometry methods. Reliable PSD sequencing results have been obtained starting with sub-picomole quantities of protein. We estimate that the current PSD sequencing limit is about 300 fmol of protein in the gel. The PSD mass spectra of the derivatized peptides usually allow much more specific protein sequence database searches than those obtained without derivatization. We also report initial automated electrospray ionization-tandem mass spectrometry sequencing of these novel peptide derivatives. Both types of tandem mass spectra provide predictable fragmentation patterns for arginine-terminated peptides. The spectra are easily interpreted de novo, and they facilitate error-tolerant identification of proteins whose sequences have been entered into databases.

A proteomic analysis was performed comparing normal rat soleus muscle to denervated soleus muscle at 0.5, 1, 2, 4, 6, 8 and 10 days post denervation. Muscle mass measurements demonstrated that the times of major mass changes occurred between 2 and 4 days post denervation. Proteomic analysis of the denervated soleus muscle during the atrophy process demonstrated statistically significant (at the p < 0.01 level) changes in 73 soleus proteins, including coordinated changes in select groups of proteins. Sequence analysis of ten differentially regulated proteins identified metabolic proteins, chaperone and contractile apparatus proteins. Together these data indicate that coordinated temporally regulated changes in the proteome occur during denervation-induced soleus muscle atrophy, including changes in muscle metabolism and contractile apparatus proteins.

We report the application of nanoelectrospray ionization tandem mass spectrometry (nES-MS/MS) and capillary LC/microelectrospray MS/MS (cLC/µES-MS/MS) for sequencing sulfonic acid derivatized tryptic peptides. These derivatives were specifically prepared to facilitate low-energy charge-site-initiated fragmentation of C-terminal arginine-containing peptides, and to enhance the selective detection of a single series of y-type fragment ions. Both singly and doubly protonated peptides were analyzed by MS/MS and the results were compared with those from their derivatized counterparts. Model peptides and peptides from tryptic digests of gel-isolated proteins were analyzed. Derivatized singly protonated peptides fragment in the same way by nES-MS/MS as they do by post-source decay matrix-assisted laser desorption/ionization mass spectrometry (PSD-MALDI-MS). They produce fragment ion spectra dominated by y-ions, and the simplified spectra are readily interpreted de novo. Doubly protonated peptides fragment in much the same way as their non-derivatized doubly protonated counterparts. The fragmentation of doubly protonated derivatives is especially useful for sequencing peptides that possess a proline residue near the N-terminus of the molecule. The singly protonated forms of these proline-containing derivatives often show enhanced fragmentation on the N-terminal side of the proline and considerably reduced fragmentation on the C-terminal side. In addition, sulfonic acid derivatization increases the in-source fragmentation of arginine-containing peptides. This could be useful for sequence verification and sequence tagging for use in single stage mass spectrometry. Copyright © 2000 John Wiley & Sons, Ltd.

Penicillin-binding protein 2a (PBP2a) is the primary beta-lactam resistance determinant of methicillin-resistant Staphylococcus aureus (MRSA). MecA, the gene coding for PBP2a, was cloned with the membrane-anchoring region at the N-terminus deleted. The truncated protein (PBP2a) was overexpressed in Escherichia coli mostly in the soluble form accounting for approximately 25% of soluble cell protein and was purified to homogeneity. The purified protein was shown to covalently bind beta-lactams in an 1:1 ratio as determined by electrospray mass spectrometry. A novel method based on HPLC-elctrospray mass spectrometry has been developed to quantitatively determine the formation of the covalent adducts or acyl-PBP2a complexes. By using this method, combined with kinetic techniques including quench flow, we have extensively characterized the interactions between PBP2a and three beta-lactams and determined related kinetic parameters for the first time. The apparent first-order rate constants (ka) of PBP2a acylation by benzylpenicillin showed a hyperbolic dependence on the concentration of benzylpenicillin. This is consistent with the mechanism that the binding of the penicillin to PBP2a consists of reversible formation of a Michaelis complex followed by formation of the penicilloyl-PBP2a adduct, and allowed the determination of the individual kinetic parameters for these two steps, the dissociation constant Kd of 13.3 mM and the first-order rate constant k2 of 0.22 s-1. From these values, the second-order rate constant k2/Kd, the value reflecting the overall binding efficiency of a beta-lactam, of 16.5 M-1 s-1 was obtained. The fairly high Kd value indicates that benzylpenicillin fits rather poorly into the protein active site. Similar studies on the interaction between PBP2a and methicillin revealed k2 of 0.0083 s-1 and Kd of 16.9 mM, resulting in an even smaller k2/Kd value of 0.49 M-1 s-1. The rate constants k3 for deacylation of the acyl-PBP2a complexes, the third step in the interactions, were measured to be

Enzymatic digests of proteins isolated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were separated by capillary high-performance liquid chromatography (HPLC). The column eluate was split to an electrospray mass spectrometer on one side and to both a UV detector and a microblotter on the other side. Using the microblotter, the peptides eluted from the column were collected directly onto a polyvinylidene difluoride (PVDF) membrane for Edman sequencing. Thus, a peptide mass map from the mass spectrometric analysis and a prepared PVDF membrane for subsequent Edman sequencing were generated in a single experiment. The addition of molecular mass information to the blotted LC eluate is useful for determining the most important peaks to undergo Edman sequencing. Coupling the capillary HPLC with a microblotter to electrospray mass spectrometry provides an integrated system for separation, collection, and structural analysis of protein digests. It provides high levels of sensitivity, recovery, and convenience for protein characterization. Proteins loaded onto SDS-PAGE at low picomole levels can be analyzed by the new integrated system.

Penicillin-binding protein 2a (PBP2a), a high molecular mass PBP, is the primary enzyme responsible for the β-lactam resistance in methicillin-resistant Staphylococcus aureus (MRSA). Inhibition of a PBP such as PBP2a by β-lactams is due to covalent modification of an active site serine residue. Based on the sequence alignment with well studied β-lactamases, DD-carboxypeptidases and other high molecular mass PBPs, the serine of a tetrad S403XXK in PBP2a was tentatively identified as the penicillin-binding site. However, direct evidence for the involvement of serine403 has not been reported. In this study, a method which combines liquid chromatography/electrospray mass spectrometry (LC/MS) and nano-electrospray MS for the identification of the active site serine in PBP2a is described. The covalent binding of the β-lactams was carried out in vitro with the recombinant PBP2a. Peptide mapping of the cyanogen bromide fragments from penicilloyl-PBP2a, using microbore LC/MS, provided a rapid identification of the modified peptide with a 334 Da mass increase. The acylated peptide was isolated and further digested with trypsin. Nano-electrospray MS/MS sequencing of the acylated peptide in the tryptic digest showed that the penicillin was indeed attached to serine403. © 1998 John Wiley & Sons, Ltd.

Crystallins, the structural proteins of the lens, have been isolated from human lenses using a combination of gel filtration and reversed phase high performance liquid chromatography (HPLC). The molecular weights of the isolated crystallins have been determined by electrospray ionization mass spectrometry. The isolated crystallins have also been proteolytically digested into peptides, the peptides fractionated by HPLC, and the masses of the peptides determined by fast atom bombardment mass spectrometry. With these techniques, it is possible to confirm and/or correct known protein sequences and identify and locate post translational modifications. I NTRODU CTl ON Cataract, which can be defined as an opacity of the eye lens, is the leading cause of blindness worldwide. In countries where surgery to remove a cataractous lens and replace it with a synthetic lens is readily available, cataract may not be a serious impairment; however, in much of the world this surgery is not available, and the development of cataract leads to blindness. The two types of cataract, cortical and nuclear, both involve changes in the lens proteins, called the crystallins. For the lens to be transparent, the crystallins must be tightly and uniformly packed producing a lens with a uniform refractive index. In cortical cataract, the density of the crystallins is altered, causing a non-uniform density with variations in the lens refractive index and consequent light scattering (ref. 1). Nuclear cataract is associated with the formation of insoluble protein aggregates. In both cases, there are modifications to the lens crystallins that either prevent their normal close packing in the cortex or cause their aggregation in the nucleus. The focus of our research is to determine which proteins are modified, where the modifications are located, and the identity of the modifications. Cataract is most commonly associated with old age. Most people over age 80 have at least early indications of cataract. Cataract occurs earlier in people with diabetes, renal failure, chronic diarrhea or who have experienced prolonged exposure to W radiation. The mechanisms that have been proposed for the development of cataract vary, depending on the disease with which it is associated. Cataract associated with old age, diabetes, renal failure and chronic diarrhea are all proposed to occur because of modifications to the lysyl residues of the crystallins. In old age, the concentration of glutathione in the lens is lower. This permits an increase in the concentration of dehydroascorbic acid, which is normally reduced by glutathione in younger lenses. Dehydroascorbic acid can react with the amino groups of the lysyl residues, forming a Schiff base which can then rearrange or possibly form cross-links (ref. 2). In diabetes, the elevated concentrations of glucose may lead to formation of a similar Schiff base between the lysyl residues and glucose (ref. 3). Both renal failure and chronic diarrhea are associated with elevated urea, which forms an equilibrium with isocyanate. Isocyanate can also react with lysyl residues forming a carbamylated protein (refs. 4, 5). A different mechanism, oxidation of the tryptophan residues to form kynurenine, has been proposed

The primary structure and posttranslational modifications of rabbit lens alpha-crystallins were examined using electrospray ionization mass spectrometry to determine the molecular weights of the intact proteins and fast atom bombardment mass spectrometry to analyze proteolytic digests of the alpha A- and alpha B-crystallins. The previously determined primary structure of alpha A-crystallin was confirmed. Posttranslational modifications detected included one phosphorylation site and the presence of a truncated form minus the five C-terminal residues. The previously undetermined amino acid sequence of rabbit alpha B-crystallin was determined to be the same as the bovine alpha B-crystallin sequence except at three residues: Thr 40, Thr 132, and Pro 153. Rabbit alpha B-crystallin showed evidence of phosphorylation at the same three sites as bovine alpha B-crystallin. The molecular weights of the intact proteins indicated that any one molecule had a maximum of two phosphorylations. Also, there was a truncated form which did not include the five C-terminal residues.

The oxidation of ascorbic acid leads to the formation of several compounds which are capable of reacting with protein amino groups via a Maillard reaction. Radioactivity from [1- 14 C]ascorbic acid was linearly incorporated into lens crystallins over a 10 day period in the presence of NaCNBH 3 . This rate of incorporation was 6–7-fold more rapid than that obtained with [[ 14 C]glucose under the same conditions. SDS-PAGE showed a linear incorporation into all the cyrstallin subunits. [1- 14 ]Ascorbic acid-label led α-crystallin was separated into into its component A and B subunits, and each was digested with chymotrypsin. HPLC peptide analysis showed a differential labelling of the various lysine residues. Analysis of the peptides by mass spectrometry allowed the identification of the sites and the extent of modification. These values ranged from 6% for Lys-78 to 36% for Lys-11 in the A subunit and from 5% for Lys-82 to an average of 38% for the peptide containing Lys-166, Lys-174 and Lys-175 in the B subunit. Amino acid analysis demonstrated a single modification reaction producing N ϵ -(carboxymethyl)lysine. This agreed with the mass increase of 58 observed for each modified peptide.

This paper described a facile method for preparation of gold nanoparticles with high efficient SERS activity within short reaction time in the presence of an environmentally benign and low-cost reagent named inositol hexaphosphate (IP(6)). IP(6) acted as a tunable cross-linker to obtain a suitable separation (about 2nm) between the neighboring particles for certain surface plasmons by adjusting the dosages of IP(6). When the molar ratio of Au to IP(6) was 10:1, gold particles presented in nano-pearl-necklace pattern, demonstrating the high enhancement factor (>10(7)) for 2-mercaptopyridine (2-Mpy) Raman scattering and high stability (>2months).

The main objective of this work was to use positive-ion fast atom bombardment mass spectrometry (FAB-MS) B/E linked scan spectra to investigate the possibility of differentiating positional isomers of various authentic glycine- and taurine-conjugated bile acids. Sodium salts of 14 conjugated bile acids were individually ionized by FAB-MS and characterized by scanning simultaneously the magnetic field B and the electric sector field E such that B/E remained constant throughout the scan. The dominant fragment ions could be related to cleavage of the aliphatic side chain with charge retention on the conjugated end of the bile acids. However, fragment ions arising from ring cleavages were also observed and could be used to distinguish the positions of substituent hydroxyl groups. For example, ring cleavage of conjugated dihydroxy bile acids at C-7/C-8 and C-9/C-10 permitted the differentiation of chenodeoxycholyltaurine (3 alpha,7 alpha-substitution pattern) from deoxycholyltaurine (3 alpha,12 alpha-substitution pattern) based on the presence of fragment ions at m/z 388 or m/z 404, which were indicative of hydroxyl group substitutions at either the 7- or 12-positions, respectively. It was concluded that B/E linked scans can be used to discriminate positional isomers of conjugated bile acids.

Peptide vaccines able to induce high affinity and protective neutralizing antibodies must rely in part on the design of antigenic epitopes that mimic the three-dimensional structure of the corresponding region in the native protein. We describe the design, structural characterization, immunogenicity, and neutralizing potential of antibodies elicited by conformational peptides derived from the human T-cell leukemia virus type 1 (HTLV-1) gp21 envelope glycoprotein spanning residues 347-374. We used a novel template design and a unique synthetic approach to construct two peptides (WCCR2T and CCR2T) that would each assemble into a triple helical coiled coil conformation mimicking the gp21 crystal structure. The peptide B-cell epitopes were grafted onto the epsilon side chains of three lysyl residues on a template backbone construct consisting of the sequence acetyl-XGKGKGKGCONH2 (where X represents the tetanus toxoid promiscuous T cell epitope (TT) sequence 580-599). Leucine substitutions were introduced at the a and d positions of the CCR2T sequence to maximize helical character and stability as shown by circular dichroism and guanidinium hydrochloride studies. Serum from an HTLV-1-infected patient was able to recognize the selected epitopes by enzyme-linked immunosorbent assay (ELISA). Mice immunized with the wild-type sequence (WCCR2T) and the mutant sequence (CCR2T) elicited high antibody titers that were capable of recognizing the native protein as shown by flow cytometry and whole virus ELISA. Sera and purified antibodies from immunized mice were able to reduce the formation of syncytia induced by the envelope glycoprotein of HTLV-1, suggesting that antibodies directed against the coiled coil region of gp21 are capable of disrupting cell-cell fusion. Our results indicate that these peptides represent potential candidates for use in a peptide vaccine against HTLV-1.

A proteomic analysis was performed comparing normal slow twitch type fiber rat soleus muscle and normal fast twitch type fiber tibialis anterior muscle to immobilized soleus and tibialis anterior muscles at 0.5, 1, 2, 4, 6, 8 and 10 days post immobilization. Muscle mass measurements demonstrate mass changes throughout the period of immobilization. Proteomic analysis of normal and atrophied soleus muscle demonstrated statistically significant changes in the relative levels of 17 proteins. Proteomic analysis of normal and atrophied tibialis anterior muscle demonstrated statistically significant changes in the relative levels of 45 proteins. Protein identification using mass spectrometry was attempted for all differentially regulated proteins from both soleus and tibialis anterior muscles. Four differentially regulated soleus proteins and six differentially regulated tibialis anterior proteins were identified. The identified proteins can be grouped according to function as metabolic proteins, chaperone proteins, and contractile apparatus proteins. Together these data demonstrate that coordinated temporally regulated changes in the proteome occur during immobilization-induced atrophy in both slow twitch and fast twitch fiber type skeletal muscle.

Publisher Summary Nano-electrospray (nES) is a new technique for characterizing biomolecules in small volumes (0.5–2 μl) at low picomole levels. In nES, signals from a single sample loading typically last more than 30 minutes, which permits optimization of instrument parameters and MS/MS sequencing with high sensitivity. Both nES/MS and nES/MS/MS data can be obtained from a single sample loading. These features make nES an attractive off-line technique for sequencing peptides collected from capillary electrophoresis (CE). In this chapter, an off-line approach that combines nES/MS analysis and Edman sequencing of peptide/protein fractions collected from CE is presented. Automatic peak collection is accomplished using a computer-controlled Beckman P/ACE 5000 instrument. An off-line approach that is simple and useful for peptide/protein sequencing using 5–10 picomoles of material has been demonstrated. Several different samples of material, including a peptide mixture (angiotensin-I, methionine enkephalin, and substance-P), a tryptic digest of cytochrome-C and proteins like myoglobin, insulin and lysozyme, are used to demonstrate this method. For this purpose, peptide and protein samples are first separated by capillary electrophoresis. Selected peaks are fraction collected and analyzed by both nano-electrospray mass spectrometry and Edman sequencing.

alpha-Crystallins from the water-soluble and the water-insoluble, guanidine-soluble portions of lenses from four renal failure patients and two normal donors of similar age were isolated and enzymatically digested into peptides. Molecular weights of the peptides, determined by fast atom bombardment mass spectrometry, indicated modifications specifically associated with renal failure. The only modifications observed in the alpha-crystallins from renal failure patients, but not in the normal old lenses, were glutathione adducts to Cys 131 and Cys 142. These adducts were present in the lenses of all four renal failure patients, but not in the two normal old lenses. The four lenses from the renal failure patients were searched for evidence of carbamylation at lysyl or cysteinyl residues: carbamylation was not detected. Because the same mass spectrometric methods had previously demonstrated sufficient sensitivity and specificity to detect as little as 5% modification in the examination of in vitro carbamylated bovine lenses, these results indicated that carbamylation is not a major modification of the lens alpha-crystallins of renal failure patients.

A combination of mass spectrometric techniques has been used to investigate the amino acid sequence and post-translational modifications of alpha B-crystallin isolated from bovine lenses by gel filtration chromatography and reversed-phase high performance liquid chromatography. Chromatographic fractions were analyzed by electrospray ionization mass spectrometry to determine the homogeneity and molecular weights of proteins in the fractions. The alpha B-crystallin primary gene product, its mono- and diphosphorylated forms, its N- and C-terminal truncated forms, as well as other lens proteins unrelated to the alpha B-crystallins were identified by their molecular weights. Detailed information about the sites of phosphorylation, as well as evidence supporting reassignment of Asn to Asp at position 80, was obtained by analyzing proteolytic digests of these proteins by fast atom bombardment mass spectrometry. Results of this investigation indicate that alpha B-crystallin is phosphorylated in vivo at Ser 45, Ser 59, and either Ser 19 or 21. From the specificity of phosphorylation of alpha-crystallins, it appears that there may be two different kinases responsible for their phosphorylation.

A new HPLC electrochemical detector that can be used to detect selectively and simultaneously both thiol- and disulfide-containing peptides is described. One electrode responds only to thiol-containing peptides, while a second electrode located downstream from a third electrode responds to thiol- as well as disulfide-containing peptides. All three electrodes are located in a single block and sample the HPLC effluent simultaneously. Since the electrochemical detector responds only to peptides that contain thiol or disulfide functionalities, it is ideal for detecting these types of peptides when they are present in complex mixtures. Peptides can be identified by their retention times if reference peptides are available, or by their molecular weights if the appropriate chromatographic fractions are collected and analyzed by mass spectrometry. The utility of the three-electrode electrochemical detector for detecting thiol- and disulfide-containing peptides in a single chromatographic analysis is illustrated with proteolytic digests of bovine alpha A-crystallin and partially reduced bovine insulin.

A new procedure to selectively identify disulfide-containing peptides in extracts of biological tissues is described. Disulfide-containing peptides are detected by their UV absorbance and electrochemical (EC) activity after chromatographic separation, and subsequently identified by fast atom bombardment mass spectrometry (FABMS). This combination of fractionation by HPLC and selective detection is attractive because it is rapid, highly specific for disulfide-containing peptides, and applicable to all disulfide-containing peptides that may be present in complex biological mixtures. Useful procedures for applying the method are demonstrated with tissue extracts from bovine pituitary and catfish pancreas. In addition to finding the expected disulfide-containing peptides, evidence for two forms of catfish insulin are presented. The merits of this and other methods used to detect peptides in similar tissue extracts are discussed.