Search

Cu(II)-peptide complexes are intensely studied as models for biological peptides and proteins and for their direct importance in copper homeostasis and dyshomeostasis in human diseases. In particular, high-affinity ATCUN/NTS (amino-terminal copper and nickel/N-terminal site) motifs present in proteins and peptides are considered as Cu(II) transport agents for copper delivery to cells. The information on the affinities and structures of such complexes derived from steady-state methods appears to be insufficient to resolve the mechanisms of copper trafficking, while kinetic studies have recently shown promise in explaining them. Stopped-flow experiments of Cu(II) complexation to ATCUN/NTS peptides revealed the presence of reaction steps with rates much slower than the diffusion limit due to the formation of novel intermediate species. Herein, the state of the field in Cu(II)-peptide kinetics is reviewed in the context of physiological data, leading to novel ideas in copper biology, together with the discussion of current methodological issues.

Preeclampsia is a blood pressure disorder associated with significant proteinuria. Hypertensive women have increased levels of neurokinin B (NKB) and Cu(II) ions in blood plasma during pregnancy. NKB bears the ATCUN/NTS N-terminal motif empowering strong Cu(II) binding in a characteristic four-nitrogen (4N) square-planar motif, but an alternative Cu(II)NKB

The human copper-binding protein metallothionein-3 (MT-3) can reduce Cu(II) to Cu(I) and form a polynuclear Cu(I)(4)-Cys(5–6) cluster concomitant with intramolecular disulfide bonds formation, but the cluster is unusually inert toward O(2) and redox-cycling. We utilized a combined array of rapid-mixing spectroscopic techniques to identify and characterize the transient radical intermediates formed in the reaction between Zn(7)MT-3 and Cu(II) to form Cu(I)(4)Zn(II)(4)MT-3. Stopped-flow electronic absorption spectroscopy reveals the rapid formation of transient species with absorption centered at 430–450 nm and consistent with the generation of disulfide radical anions (DRAs) upon reduction of Cu(II) by MT-3 cysteine thiolates. These DRAs are oxygen-stable and unusually long-lived, with lifetimes in the seconds regime. Subsequent DRAs reduction by Cu(II) leads to the formation of a redox-inert Cu(I)(4)-Cys(5) cluster with short Cu–Cu distances (

The purpose of this essay is to propose that metallomic studies in the area of extracellular copper transport are incomplete without the explicit consideration of kinetics of Cu2+ion binding and exchange reactions. The kinetic data should be interpreted in the context of time constraints imposed by specific physiological processes. Examples from experimental studies of Cu2+ ion interactions with amino-terminal copper and nickel binding site/N-terminal site motifs are used to demonstrate that duration and periodicity of such processes as bloodstream transport or neurotransmission promote the reaction intermediates to the role of physiological effectors. The unexpectedly long lifetimes of intermediate complexes lead to their accumulation and novel reactivities. The emerging ideas are discussed in the context of other research areas in metallomics.

The toolset of mass spectrometry (MS) is still expanding, and the number of metal ion complexes researched this way is growing. The Cu(II) ion forms particularly strong peptide complexes of biological interest which are frequent objects of MS studies, but quantitative aspects of some reported results are at odds with those of experiments performed in solution. Cu(II) complexes are usually characterized by fast ligand exchange rates, despite their high affinity, and we speculated that such kinetic lability could be responsible for the observed discrepancies. In order to resolve this issue, we selected peptides belonging to the ATCUN family characterized with high and thoroughly determined Cu(II) binding constants and re-estimated them using two ESI-MS techniques: standard conditions in combination with serial dilution experiments and very mild conditions for competition experiments. The sample acidification, which accompanies the electrospray formation, was simulated with the pH–jump stopped-flow technique. Our results indicate that ESI-MS should not be used for quantitative studies of Cu(II)–peptide complexes because the electrospray formation process compromises the entropic contribution to the complex stability, yielding underestimations of complex stability constants.

Human serum albumin (HSA) and the growth factor glycyl-l-histidyl-l-lysine (GHK) bind Cu2+ as part of their normal functions. GHK is found at its highest concentration in the albumin-rich fraction of plasma, leading to speculation that HSA and GHK form a ternary Cu2+ complex. Although preliminary evidence was presented 40 years ago, the structure and stability of such a complex have remained elusive. Here, we show that two ternary Cu(GHK)NImHSA complexes are formed between GHK and the imino nitrogen (NIm) of His side chains of HSA. We identified His3 as one site of ternary complex formation (conditional binding constant cKCu(GHK)NImHis3Cu(GHK) = 2900 M-1 at pH 7.4), with the second site (cKCu(GHK)NImHisXCu(GHK) = 1700 M-1) likely being supplied by either His128 or His510. Together with the established role of HSA as a molecular shuttle in the blood, these complexes may aid the transport of the exchangeable Cu2+ pool and the functional form of GHK.

Gly-His-Lys (GHK) is a tripeptide present in the human bloodstream that exhibits a number of biological functions. Its activity is attributed to the copper-complexed form, Cu(II)GHK. Little is known, however, about the molecular aspects of the mechanism of its action. Here, we examined the reaction of Cu(II)GHK with reduced glutathione (GSH), which is the strongest reductant naturally occurring in human plasma. Spectroscopic techniques (UV–vis, CD, EPR, and NMR) and cyclic voltammetry helped unravel the reaction mechanism. The impact of temperature, GSH concentration, oxygen access, and the presence of ternary ligands on the reaction were explored. The transient GSH-Cu(II)GHK complex was found to be an important reaction intermediate. The kinetic and redox properties of this complex, including tuning of the reduction rate by ternary ligands, suggest that it may provide a missing link in copper trafficking as a precursor of Cu(I) ions, for example, for their acquisition by the CTR1 cellular copper transporter., Gly-His-Lys (GHK) is a human bioactive tripeptide thought to be activated by Cu(II) binding, but little is known about the molecular aspects of its action. UV−vis, circular dichroism (CD), EPR, and NMR spectroscopies, and cyclic voltammetry were used to examine the reduction of Cu(II)GHK with glutathione (GSH), the most abundant biological thiol. A semistable GSH-Cu(II)GHK reaction intermediate was discovered, with properties suitable for delivering Cu(I) to biological transport proteins.

Copper(II) complexes of peptides with a histidine residue at the second position (His2 peptides) provide a unique profile of electrochemical behavior, offering signals of both Cu(II) reduction and Cu(II) oxidation. Furthermore, their structures with vacant positions in the equatorial coordination plane could facilitate interactions with other biomolecules. In this work, we designed a library of His2 peptides based on the sequence of Aβ

Hepcidin (DTHFPICIFCCGCCHRSKCGMCCKT), an iron regulatory hormone is a 25 amino acid peptide with 4 intramolecular disulfide bonds, circulating in blood. Its hormonal activity is indirect and consists of marking ferroportin-1 (an iron exporter) for degradation. Hepcidin biosynthesis involves N-terminally extended precursors prepro-hepcidin and pro-hepcidin, processed by peptidases to the final 25-peptide form. A sequence-specific formation of disulfide bonds and export of the oxidized peptide to the bloodstream follows. In this study we considered the fact that prior to export, reduced hepcidin may function as an octathiol ligand bearing some resemblance to the N-terminal part of α-domain of metallothioneins. Consequently, we studied its ability to bind Zn(II) and Cd(II) ions using the original peptide and a model for prohepcidin, extended N-terminally with a stretch of five arginine residues (5R-hepcidin). We found that both form equivalent mononuclear complexes with two Zn(II) or Cd(II) ions saturating all eight Cys residues. The average affinity at pH 7.4, determined from pH-metric spectroscopic titrations, is 1010.1 M-1 for Zn(II) ions, the Cd(II) ions bind with affinities of 1015.2 M-1 and 1014.1 M-1. Using mass spectrometry and 5R-hepcidin we demonstrated that hepcidin can compete for Cd(II) ions with metallothionein-2, a cellular cadmium target. These studied empowered us to conclude that hepcidin binds Zn(II) and Cd(II) sufficiently strongly to participate in zinc physiology and cadmium toxicity under intracellular conditions.

Litewski Square is widely known as the place where the Lithuanian envoys camped to attend the Union Sejm in 1569. Today, Litewski Square represents a space of transformation. The urban public spaces of the square have been rebuilt several times, each instance delineating a distinct rendering of tradition and history. In this article, the evolution of the square is presented in order to analyse three main aspects. Over the years and under changing political conditions, its meaning, role, and function have shifted. Traditions and symbols that shape the space of the square have changed; these changing symbols have influenced how the meaning and functionality of the square have evolved over time. The research methodology of this paper is based on historical and interpretative studies. This form of analysis made it possible to identify the successive stages of the transformation of Litewski Square and, accordingly, in the context of changing political conditions, identify the elements that are important for the meaning of the square today. Litewski Square has evolved from an urban space with a clearly defined function to a multifunctional public space: from a memorial square into a modern space of leisure and entertainment. This paper argues that the accumulation of commemorative elements and directly adjacent recreational spaces give the impression of a lapidary, the constituent elements of which devalue each other. What this means is that, even as the number of commemorative symbolic elements have increased, their status is degraded, as well as that of Litewski Square as a whole.

City pigeons (Columba livia forma urbana) are an integral part of the urbanized environment. However, they host parasites that can be passed zoonotically to humans and to domestic and wild birds. The aim of the study was to establish the current prevalence of nematode and coccidians infestation among city pigeons roosting in old buildings in Szczecin. The pigeon kits, comprising city pigeons and stray breeding pigeons which had not returned to their lofts, numbered from 45 to 60 individuals. Samples of pigeon droppings were tested qualitatively by the flotation method and then quantitatively by the McMaster technique. Oocyst culture was also performed in a humid chamber at a temperature of 24–26° C. The oocytes were identified using standard keys. Two roundworm families were identified, Ascaridia spp. (two species) and Capillaria spp., and three coccidian species: Eimeria labbeana, E.columbarum and E. columbae. Overall, the extent of infection was approximately 100% throughout the study area, but varied depending on the place of origin of the material. The prevalence of worms with eggs ranged from 9% to 16% for Ascaris spp. and 24–41% for Capillaria spp. The maximum OPG values, i.e. the number of oocytes per gram of faeces, were 360 for Ascaris spp. and 1134 for Capillaria spp; these indicate the intensity of infection. The most frequently observed species was Eimeria labbeana, whose prevalence was found to range from 82% to 96% depending on location, with a mean infection intensity of 1130–1870 OPG. The prevalence of the other two Eimeria species was also high, with respectively values of 56–77% for E. columbarum and 32–43% for E. columbae, depending on the location. The mean OPG values for the species were 430–1770 and 29–52, respectively. Maximum OPG values were 223,000 for E. labbeana, 54,000 for E. columbarum and 830 for E. columbae.

Microscale thermophoresis (MST), and the closely related Temperature Related Intensity Change (TRIC), are synonyms for a recently developed measurement technique in the field of biophysics to quantify biomolecular interactions, using the (capillary-based) NanoTemper Monolith and (multiwell plate-based) Dianthus instruments. Although this technique has been extensively used within the scientific community due to its low sample consumption, ease of use, and ubiquitous applicability, MST/TRIC has not enjoyed the unambiguous acceptance from biophysicists afforded to other biophysical techniques like isothermal titration calorimetry (ITC) or surface plasmon resonance (SPR). This might be attributed to several facts, e.g., that various (not fully understood) effects are contributing to the signal, that the technique is licensed to only a single instrument developer, NanoTemper Technology, and that its reliability and reproducibility have never been tested independently and systematically. Thus, a working group of ARBRE-MOBIEU has set up a benchmark study on MST/TRIC to assess this technique as a method to characterize biomolecular interactions. Here we present the results of this study involving 32 scientific groups within Europe and two groups from the US, carrying out experiments on 40 Monolith instruments, employing a standard operation procedure and centrally prepared samples. A protein-small molecule interaction, a newly developed protein-protein interaction system and a pure dye were used as test systems. We characterized the instrument properties and evaluated instrument performance, reproducibility, the effect of different analysis tools, the influence of the experimenter during data analysis, and thus the overall reliability of this method. All authors acknowledge the COST Action project ARBRE-MOBIEU CA15126 under the auspices of whose Working Group 4 this study was carried out. ARBRE-MOBIEU COST Action CA15126 funded meetings in the Center for Protein Research, University of Copenhagen (ECOST-MEETING-CA15126-280618-098884) to organize this study and in the Vienna Biocenter Core Facilities GmbH (ECOST-MEETING-CA15126-121119-111544) to discuss the results of the benchmark. Ondřej Vaněk acknowledges support from the Ministry of Education, Youth and Sports of the Czech Republic (LTC17065 in frame of the COST Action CA15126). Jitka Holková and Josef Houser acknowledge CF Biomolecular Interactions and Crystallization of CIISB, Instruct-CZ Centre, supported by MEYS CR (LM2018127). Jasmina Rokov-Plavec acknowledges support from the Croatian Science Foundation (IP-2016-06-6272). Alexander K. Buell thanks the Novo Nordisk Foundation (grant number NNFSA170028392) for funding. Li Peng Lundgren acknowledges for preliminary MST/TRIC experiments (STMS 37745 in the frame of the COST Action CA15126) and the COST Action (CA15126) for a STMS (STMS 44783) for the data analysis. The Novo Nordisk Foundation Center for Protein Research is supported financially by the Novo Nordisk Foundation (Grant agreement NNF14CC0001). Katja Pirc and Marjetka Podobnik acknowledge the grant by the Slovenian Research Agency P1-0391 (Title: Molecular Interactions). This research was funded by Fondo de Investigaciones Sanitarias from Instituto de Salud Carlos III and European Union (ERDF/ESF, “Investing in your future” PI18/00349 and Diputación General de Aragón Digestive Pathology Group B25_17R to O.A. Spanish Ministry of Science, Innovation and Universities, FPI Predoctoral Research Contract BES-2017-080739 to D.O.A. This research was funded by project no 2015/17/B/NZ2/01160 (granted to MA)

The practice of promoting an image of the city using architectural objects, and the need to identify or create architectural icons in urban spaces, outlined in this article, occurs in many cities worldwide. The city of Szczecin in Poland, the subject of this research, is no exception. The turbulent history of the city, which for years remained within the borders of Germany, makes it particularly worth analyzing in these terms because it shows the shifting popularity of architectural objects in the context of changing political, cultural, and economic conditions. The research presented here aims to identify iconic objects commonly exploited to build an image of Szczecin, assess their prominent features, and analyze changes over time in their popularity and use for these purposes. The historical and interpretive research was based on a detailed analysis of old and contemporary architectural objects of Szczecin depicted in postcards from the last hundred years, from the period spanning 1920 to 2023. The analysis covered several digital databases containing archival and contemporary postcards. This analysis enables the identification of the most popular objects, suggests the key characteristics of iconic buildings, and identifies four basic types of buildings, which are distinct in terms of purpose, message, and the specific image of the city to which each contributes. The duration of each type as a popular object, the strength of its impact on the city’s image, and its importance for the urban landscape are also identified. The research revealed that: architecturally iconic buildings are created concerning political, economic, and social conditions and the need to promote a specific image of the city, certain features contribute to a building’s potential as an architectural icon, and the strength of the building’s impact, its importance for the city landscape, and the possibility of creating a specific image depending on its iconic type.

Alzheimer's disease (AD) is one of the most common of the multifactorial diseases and is characterized by a range of abnormal molecular processes, such as the accumulation of extracellular plaques containing the amyloid-β (Aβ) peptides and dyshomeostasis of copper in the brain. In this study, we have investigated the effect of CuII on the aggregation of Aβ1-40 and Aβ4-40 , representing the two most prevalent families of Aβ peptides, that is, the full length and N-truncated peptides. Both families are similarly abundant in healthy and AD brains. For either of the studied peptides, substoichiometric CuII concentrations accelerated aggregation, whereas superstoichiometric CuII inhibited fibril formation, likely by stabilizing the oligomers. The addition of either Aβ4-40 or substoichiometric CuII affected the aggregation profile of Aβ1-40 , by yielding shorter and thicker fibrils; amorphous aggregates were formed in the presence of a molar excess of CuII . The similarity of these two effects can be attributed to the increase in the positive charge on the Aβ N terminus, caused both by CuII complexation and N truncation at position 4. Our findings provide a better understanding of the biological Aβ aggregation process as these two Aβ species and CuII coexist and interact under physiological conditions.

Covalent protein kinase inhibitors exploit currently noncatalytic cysteines in the adenosine 5′-triphosphate (ATP)-binding site via electrophiles directly appended to a reversible-inhibitor scaffold. Here, we delineate a path to target solvent-exposed cysteines at a distance >10 Å from an ATP-site-directed core module and produce potent covalent phosphoinositide 3-kinase α (PI3Kα) inhibitors. First, reactive warheads are used to reach out to Cys862 on PI3Kα, and second, enones are replaced with druglike warheads while linkers are optimized. The systematic investigation of intrinsic warhead reactivity (kchem), rate of covalent bond formation and proximity (kinactand reaction space volume Vr), and integration of structure data, kinetic and structural modeling, led to the guided identification of high-quality, covalent chemical probes. A novel stochastic approach provided direct access to the calculation of overall reaction rates as a function of kchem, kinact, Ki, and Vr, which was validated with compounds with varied linker lengths. X-ray crystallography, protein mass spectrometry (MS), and NanoBRET assays confirmed covalent bond formation of the acrylamide warhead and Cys862. In rat liver microsomes, compounds 19 and 22 outperformed the rapidly metabolized CNX-1351, the only known PI3Kα irreversible inhibitor. Washout experiments in cancer cell lines with mutated, constitutively activated PI3Kα showed a long-lasting inhibition of PI3Kα. In SKOV3 cells, compounds 19 and 22 revealed PI3Kβ-dependent signaling, which was sensitive to TGX221. Compounds 19 and 22 thus qualify as specific chemical probes to explore PI3Kα-selective signaling branches. The proposed approach is generally suited to develop covalent tools targeting distal, unexplored Cys residues in biologically active enzymes., Journal of the American Chemical Society, 144 (14), ISSN:0002-7863, ISSN:1520-5126

Amyloid beta (Aβ) peptides are notorious for their involvement in Alzheimer's disease (AD), by virtue of their propensity to aggregate to form oligomers, fibrils, and eventually plaques in the brain. Nevertheless, they appear to be essential for correct neurophysiology on the synaptic level and may have additional functions including antimicrobial activity, sealing the blood-brain barrier, promotion of recovery from brain injury, and even tumor suppression. Aβ peptides are also avid copper chelators, and coincidentally copper is significantly dysregulated in the AD brain. Copper (Cu) is released in significant amounts during calcium signaling at the synaptic membrane. Aβ peptides may have a role in maintaining synaptic Cu homeostasis, including as a scavenger for redox-active Cu and as a chaperone for clearing Cu from the synaptic cleft. Here, we employed the Aβ1-16 and Aβ4-16 peptides as well-established non-aggregating models of major Aβ species in healthy and AD brains, and the Ctr1-14 peptide as a model for the extracellular domain of the human cellular copper transporter protein (Ctr1). With these model peptides and a number of spectroscopic techniques, we investigated whether the Cu complexes of Aβ peptides could provide Ctr1 with either Cu(II) or Cu(I). We found that Aβ1-16 fully and rapidly delivered Cu(II) to Ctr1-14 along the affinity gradient. Such delivery was only partial for the Aβ4-16/Ctr1-14 pair, in agreement with the higher complex stability for the former peptide. Moreover, the reaction was very slow and took ca. 40 h to reach equilibrium under the given experimental conditions. In either case of Cu(II) exchange, no intermediate (ternary) species were present in detectable amounts. In contrast, both Aβ species released Cu(I) to Ctr1-14 rapidly and in a quantitative fashion, but ternary intermediate species were detected in the analysis of XAS data. The results presented here are the first direct evidence of a Cu(I) and Cu(II) transfer between the human Ctr1 and Aβ model peptides. These results are discussed in terms of the fundamental difference between the peptides' Cu(II) complexes (pleiotropic ensemble of open structures of Aβ1-16 vs the rigid closed-ring system of amino-terminal Cu/Ni binding Aβ4-16) and the similarity of their Cu(I) complexes (both anchored at the tandem His13/His14, bis-His motif). These results indicate that Cu(I) may be more feasible than Cu(II) as the cargo for copper clearance from the synaptic cleft by Aβ peptides and its delivery to Ctr1. The arguments in favor of Cu(I) include the fact that cellular Cu export and uptake proteins (ATPase7A/B and Ctr1, respectively) specifically transport Cu(I), the abundance of extracellular ascorbate reducing agent in the brain, and evidence of a potential associative (hand-off) mechanism of Cu(I) transfer that may mirror the mechanisms of intracellular Cu chaperone proteins.

The Aβ5–x peptides (x = 38, 40, 42) are minor Aβ species in normal brains but elevated upon the application of inhibitors of Aβ processing enzymes. They are interesting from the point of view of co...

NiO nanoparticles and non-stoichiometric black NiO were shown to be effective sources of Ni2+ ions causing sequence-selective peptide bond hydrolysis. NiO nanoparticles were as effective in this reaction as their molar equivalent of soluble Ni(ii) salt. These findings highlight the efficacy of delivery of toxic Ni2+ by these environmentally available particles.

N-Truncated Aβ4–42 displays a high binding affinity with CuII. A mechanistic scheme of the interactions between Aβ4–42 and CuII has been proposed using a fluorescence approach. The timescales of different conversion steps were determined. This kinetic mechanism indicates the potential synaptic functions of Aβ4–42 during neurotransmission.

Aβ4–42 is the major subspecies of Aβ peptides characterized by avid Cu(II) binding via the ATCUN/NTS motif. It is thought to be produced in vivo proteolytically by neprilysin, but in vitro experiments in the presence of Cu(II) ions indicated preferable formation of C-terminally truncated ATCUN/NTS species including CuIIAβ4–16, CuIIAβ4–9, and also CuIIAβ12–16, all with nearly femtomolar affinities at neutral pH. Such small complexes may serve as shuttles for copper clearance from extracellular brain spaces, on condition they could survive intracellular conditions upon crossing biological barriers. In order to ascertain such possibility, we studied the reactions of CuIIAβ4–16, CuIIAβ4–9, CuIIAβ12–16, and CuIIAβ1–16 with reduced glutathione (GSH) under aerobic and anaerobic conditions using absorption spectroscopy and mass spectrometry. We found CuIIAβ4–16 and CuIIAβ4–9 to be strongly resistant to reduction and concomitant formation of Cu(I)–GSH complexes, with reaction times ∼10 h, while CuIIAβ12–16 was reduced within minutes and CuIIAβ1–16 within seconds of incubation. Upon GSH exhaustion by molecular oxygen, the CuIIAβ complexes were reformed with no concomitant oxidative damage to peptides. These finding reinforce the concept of Aβ4–x peptides as physiological trafficking partners of brain copper., Aβ4−16, Aβ4−9, and Aβ12−16, oligopeptide products of β-amyloid degradation by neprilysin, bind CuII ions very tightly and are considered as possible CuII carriers in the brain. We demonstrated that CuII(Aβ4−x) complexes, but not CuII(Aβ12−16), are kinetically resistant to reduction by glutathione. No covalent Aβ peptide modifications were observed during the copper reduction and reoxidation by ambient oxygen, yielding the original complexes. These features suggest that CuII(Aβ4−x) complexes might be able to cross the blood−brain barrier.

The stochastic nature of chemical reaction and impact of the stochasticity on their evolution is soundly documented. Both theoretical predictions and emerging experimental evidence indicate the influence of stochastic effects on the equilibrium state of association reaction. In this work simple mathematical formulas are introduced to estimate these effects. First, the dependence of the ratio of observed reactants (apparent association constant, equivalent of macroscopic association constant in stochastic analysis) on the volume and the number of molecules of reagents is discussed and the limiting factors of this effect are shown. Next, the apparent association constant is approximated for nanoscale systems by closed-form formulas derived for this purpose. Finally, an estimation for the macroscopic constant value from the apparent one is provided and validated on the published experimental data. This work was inspired by chemical reactions occurring in biological compartments, but the results can be used for all systems belonging to the stochastic regime of chemical reactions.

International audience; The impact on human health of long-term exposure to low doses of silver nanoparticles (AgNPs) remainsunderstudied. Cellular studies have shown the intracellular dissolution of AgNPs within endolysosomesfollowed by Ag(I) binding to biomolecular thiolate-containing molecules. However, the precise subcellulardistribution of Ag(I) and the nature of the disrupted physiological pathways remained unknown. Novelimaging approaches enabled us to visualize the trafficking of AgNP-containing lysosomes towards aperinuclear location and a nuclear transfer of Ag(I) species with accumulation in the nucleoli. These Ag(I)species impaired nuclear receptor activity, disrupting critical mechanisms of liver physiology in low doseexposure scenarios, thus justifying further research into defining a framework for the safe use of AgNPs.

International audience; Silver (Ag(I)) binding to consensus zinc fingers (ZFs) causes Zn(II) release inducing a gradual disruption of the hydrophobic core, followed by an overall conformational change and formation of highly stable AgnSn clusters. A compact eight-membered Ag4S4 structure formed by a CCCC ZF is the first cluster example reported for a single biological molecule. Ag(I)-induced conformational changes of ZFs can, as a consequence, affect transcriptional regulation and other cellular processes.

We used a series of modified/substituted GGH analogues to investigate the kinetics of Cu(ii) binding to ACTUN peptides. Rules for rate modulation by 1st and 2nd sphere interactions were established, providing crucial insight into elucidation of the reaction mechanism and its contribution to biological copper transport.

Human serum albumin (HSA) and the growth factor glycyl-l-histidyl-l-lysine (GHK) bind Cu

The apparent affinity of human serum albumin (HSA) for divalent copper has long been the subject of great interest, due to its presumed role as the major Cu2+ -binding ligand in blood and cerebrospinal fluid. Using a combination of electronic absorption, circular dichroism and room-temperature electron paramagnetic resonance spectroscopies, together with potentiometric titrations, we competed the tripeptide GGH against HSA to reveal a conditional binding constant of log c K Cu Cu ( HSA ) =13.02±0.05 at pH 7.4. This rigorously determined value of the Cu2+ affinity has important implications for understanding the extracellular distribution of copper.

As life expectancy increases, the number of people affected by progressive and irreversible dementia, Alzheimer’s Disease (AD), is predicted to grow. No drug designs seem to be working in humans, a...

Oligomers of Aβ peptide are implicated as the most probable causative agent in Alzheimer’s disease. However, their structural properties remain elusive due to the dynamic and heterogeneous character of oligomeric species coexisting in solution. Nevertheless, new approaches, mainly based on mass spectrometry, provide unique access to these different structural forms. Using these methods, we previously showed that the N-terminal, non-amyloidogenic region of Aβ is involved in the network of interactions specifically stabilizing oligomers. In the present study, we identified three histidine residues as active participants in this network. Detailed knowledge of the structural features that are potentially important for oligomer-mediated neurotoxicity is a prerequisite for the rational design of oligomerization modifiers.