Publications by authors named "Wei-Hui Wu"

19 Publications

  • Page 1 of 1

A Fluorogenic and Chromogenic Probe Distinguishes Fluoride Anions and Thiols: Implications for Discrimination of Fluoride-Containing G Series and Sulfur-Containing V Series Nerve Agents.

J Fluoresc 2021 Jan 3;31(1):141-149. Epub 2020 Nov 3.

Institute of Chemical Defence, Beijing, 102205, People's Republic of China.

A coumarin-based probe, FP2, was designed for the differential detection of fluoride anions and thiols, i.e., the corresponding nucleophilic substitution products from fluorine-containing G agents and sulfur-containing V agents, thus having the potential to discriminate between these two nerve agents. FP2 with two functional reaction groups, α, β-unsaturated ketone and silyl groups, can react selectively with fluoride anions and thiols at the μM level respectively. Intriguingly, in the THF solution, FP2 reacts with the fluoride anion but not with the thiol, whereas in the EtOH/HEPES solution, FP2 reacts with the thiol but not with the fluoride anion. As a result, FP2 can produce different fluorophores in the two detection solutions, thus displaying significant fluorescence changes. In addition, the FP2 detection system can show a significant color change from colorless to yellow within seconds when detecting fluoride anions in THF detection solutions, and from yellow to light blue when detecting thiols in EtOH/HEPES solutions, which will facilitate visual detection by emergency responders at the scene of an incident involving a nerve agent.
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http://dx.doi.org/10.1007/s10895-020-02644-6DOI Listing
January 2021

Fibrillar seeds alleviate amyloid-β cytotoxicity by omitting formation of higher-molecular-weight oligomers.

Biochem Biophys Res Commun 2013 Sep 6;439(3):321-6. Epub 2013 Sep 6.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China; Institute of Chemical Defence, Beijing 102205, PR China.

Amyloid-β (Aβ) peptides can exist in distinct forms including monomers, oligomers and fibrils, consisting of increased numbers of monomeric units. Among these, Aβ oligomers are implicated as the primary toxic species as pointed by multiple lines of evidence. It has been suggested that toxicity could be rendered by the soluble higher-molecular-weight (high-n) Aβ oligomers. Yet, the most culpable form in the pathogenesis of Alzheimer's disease (AD) remains elusive. Moreover, the potential interaction among the insoluble fibrils that have been excluded from the responsible aggregates in AD development, Aβ monomers and high-n oligomers is undetermined. Here, we report that insoluble Aβ fibrillar seeds can interact with Aβ monomers at the stoichiometry of 1:2 (namely, each Aβ molecule of seed can bind to two Aβ monomers at a time) facilitating the fibrillization by omitting the otherwise mandatory formation of the toxic high-n oligomers during the fibril maturation. As a result, the addition of exogenous Aβ fibrillar seeds is seen to rescue neuronal cells from Aβ cytotoxicity presumably exerted by high-n oligomers, suggesting an unexpected protective role of Aβ fibrillar seeds.
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http://dx.doi.org/10.1016/j.bbrc.2013.08.088DOI Listing
September 2013

A covalently reactive group-modified peptide that specifically reacts with lysine16 in amyloid β.

Chem Commun (Camb) 2012 Nov;48(85):10565-7

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China.

Lys16 is present in the core region of the amyloid β (Aβ) self-assembly in Alzheimer's disease. Here we report that the P9-NCS peptide can covalently react with Lys16 and inhibit Aβ neurotoxic fibrillization. Moreover P9-NCS has high selectivity and it cannot react with amylin, insulin, fetal bovine serum, Q11 and MUC1 peptide.
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http://dx.doi.org/10.1039/c2cc35178aDOI Listing
November 2012

Fluorogenic and chromogenic probe for rapid detection of a nerve agent simulant DCP.

Analyst 2012 Jul 24;137(14):3224-6. Epub 2012 May 24.

Institute of Chemical Defence, Beijing 102205, PR China.

A fluorogenic and visual probe was devised to detect diethyl chlorophosphate (DCP), a nerve agent simulant. The probe, N-(rhodamine B)-lactam-2-aminoethanol (RB-AE), undergoes oxazoline formation following phosphorylation in the presence of DCP, which gives rapid and clear fluorescence and color change in the assay solutions.
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http://dx.doi.org/10.1039/c2an35428dDOI Listing
July 2012

Copper inducing Aβ42 rather than Aβ40 nanoscale oligomer formation is the key process for Aβ neurotoxicity.

Nanoscale 2011 Nov 26;3(11):4746-51. Epub 2011 Sep 26.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, 100084, China.

Copper is known to be a critical factor in Alzheimer's disease (AD) pathogenesis, as it is involved in amyloid-β (Aβ) peptide related toxicity. However, the relationship between neurotoxicity and Aβ peptide in the presence of copper remains unclear. The effect of copper has not been clearly differentiated between Aβ42 and Aβ40, and it is still debated whether copper-mediated neurotoxicity is due to reactive oxygen species (ROS) accumulation or other molecular mechanisms. Here, we describe that copper dramatically affects Aβ42 aggregation and enhances Aβ42 cytotoxicity while it shows no significant effects on Aβ40. These phenomena are mainly because that the strong interactions between copper and Aβ42 lead to great conformation changes, and stabilize Aβ42 aggregates at highly toxic nanoscale oligomer stage, whereas copper shows no similar impact on Aβ40. We also propose a possible molecular mechanism that copper enhances Aβ42 cytotoxicity via perturbing membrane structure. Moreover, we test the effect of an analogue of copper, nickel, on Aβ aggregation and cytotoxicity, finding that nickel also enhances cytotoxicity via Aβ42 nanoscale oligomer formation. These results clarify that the copper-induced Aβ42 nanoscale oligomer formation is the key process for Aβ neurotoxicity, and suggest that disrupting the interactions between copper and Aβ42 peptide to inhibit nanoscale oligomerization process, deserves more attention in AD drug development.
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http://dx.doi.org/10.1039/c1nr11029bDOI Listing
November 2011

Mapping ApoE/Aβ binding regions to guide inhibitor discovery.

Mol Biosyst 2011 May 16;7(5):1693-700. Epub 2011 Mar 16.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, PR China.

Blocking the interaction between the E4 isoform of apolipoprotein E (ApoE) and amyloid beta-peptide (Aβ) may be an avenue for pharmacological intervention in Alzheimer's disease (AD). The main regions of interaction of the two proteins are, respectively, ApoE244-272 and Aβ12-28. These protein segments are too large to facilitate the design of small molecule inhibitors. We mapped the primary components of ApoE/Aβ interaction to smaller peptide segments. Within the three motifs that are primarily responsible for ApoE/Aβ interaction, we identified four peptides that substantially block ApoE/Aβ interaction and further improved their inhibitory activity by rational hydrophobic amino acid substitution. Moreover, the mapping results provide the clue that the Aβ residues which interact with ApoE appear to be in the same region where Aβ self-interacts. According to this information, we found that Congo Red and X-34 could strongly inhibit ApoE/Aβ interaction. Our findings extend our understanding of ApoE/Aβ interaction and may guide the discovery of inhibitors that treat AD by antagonizing ApoE/Aβ interaction.
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http://dx.doi.org/10.1039/c1mb05019bDOI Listing
May 2011

Cyclen-hybrid compound captures copper to protect INS-1 cells from islet amyloid polypeptide cytotoxicity by inhibiting and lysing effects.

Chem Commun (Camb) 2010 Nov 21;46(42):8023-5. Epub 2010 Sep 21.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China.

Human islet amyloid polypeptide (hIAPP) deposit is the hallmark of type 2 diabetes pathology. Here, we report that apo-cyclen, attached to a specific hIAPP recognition motif (NYGAIL), captured copper ions and became proteolytically active. This cyclen-NYGAIL-copper complex was able to interfere with hIAPP aggregation and cleave hIAPP. These activities rescued INS-1 cells from hIAPP induced cytotoxicity.
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http://dx.doi.org/10.1039/c0cc02555kDOI Listing
November 2010

Copper-induced cytotoxicity: reactive oxygen species or islet amyloid polypeptide oligomer formation.

Chem Commun (Camb) 2010 Oct 23;46(37):6909-11. Epub 2010 Aug 23.

The Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of education), Department of Chemistry, Tsinghua University, Beijing 100084, China.

Copper enhances amyloid cytotoxicity and mediates human islet amyloid polypeptide (hIAPP) oligomerization; nickel, a redox inactive metal with similar protein binding affinity to copper, also mimics this effect, thereby demonstrating copper-mediated hIAPP cytotoxicity is due mainly to granular oligomer generation rather than ROS accumulation in type 2 diabetes.
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http://dx.doi.org/10.1039/c0cc02141eDOI Listing
October 2010

Dual functions of beta-amyloid oligomer and fibril in Cu(II)-induced H2O2 production.

Regul Pept 2010 Aug 15;163(1-3):1-6. Epub 2010 May 15.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology, Ministry of Education, Department of Chemistry, Tsinghua University, Beijing, PR China.

Amyloid-beta (Abeta) aggregation and Cu(II)-related oxidative stress are involved in the dysfunction and death of neurons in Alzheimer's disease (AD). However, the relationship between Abeta and Cu(II) is not clear. Furthermore, the pro- or anti-oxidant properties of Abeta are also under great debate. Here the H2O2 generating ability of Abeta42 in its monomeric, oligomeric and fibrillar forms was studied in the presence of Cu(II). The results show that Abeta42 in both oligomeric and fibrillar forms can promote H2O2 generation at lower concentrations of Cu(II) and Abeta42 oligomer can promote H2O2 generation to a higher extent. Nevertheless, the promoting effect of Abeta42 oligomer and fibril may convert to an inhibitory effect when the concentration of Cu(II) is increased. This indicates the dual functions of Abeta42 oligomer and fibril in Cu(II)-induced H2O2 production. Hereby we present a new perspective on the roles of Abeta42 in Cu(II)-mediated oxidative stress and add new evidence to the viewpoint that Abeta42 oligomer may be primarily responsible for the pathogenesis of AD.
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http://dx.doi.org/10.1016/j.regpep.2010.05.001DOI Listing
August 2010

Insulin is a kinetic but not a thermodynamic inhibitor of amylin aggregation.

FEBS J 2009 Jun 11;276(12):3365-71. Epub 2009 May 11.

Department of Chemistry, Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Tsinghua University, Beijing, China.

One of the most important pathological features of type 2 diabetes is the formation of islet amyloid, of which the major component is amylin peptide. However, the presence of a natural inhibitor such as insulin may keep amylin stable and physiologically functional in healthy individuals. Some previous studies demonstrated that insulin was a potent inhibitor of amylin fibril formation in vitro, but others obtained contradictory results. Hence, it is necessary to elucidate the effects of insulin on amylin aggregation. Here we report that insulin is a kinetic inhibitor of amylin aggregation, only keeping its inhibitory effect for a limited time period. Actually, insulin promotes amylin aggregation after long-term incubation. Furthermore, we found that this promotional effect could be attributed to the copolymerization of insulin and amylin. We also found that insulin copolymerized with amylin monomer or oligomer rather than preformed amylin fibrils. These results suggest that the interaction between insulin and amylin may contribute not only to the inhibition of amylin aggregation but also to the coaggregation of both peptides in type 2 diabetes.
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http://dx.doi.org/10.1111/j.1742-4658.2009.07061.xDOI Listing
June 2009

Hybrid peptides attenuate cytotoxicity of beta-amyloid by inhibiting its oligomerization: implication from solvent effects.

Peptides 2009 Jul 3;30(7):1282-7. Epub 2009 May 3.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China.

Abnormal assembly of monomeric beta-amyloid (Abeta) in Alzheimer's disease leads to the formation of most neurotoxic oligomers in vivo. In this study, we explored a linking strategy to design hybrid peptides, by combining the Abeta recognition motif and the solvent disruptive sequences. We found that in vitro all synthetic peptides with the recognition motif can affect Abeta fibrillization and alter the morphology of Abeta aggregates variously, different from those without the recognition motif. The effects of peptides containing recognition motif on Abeta aggregation correlate with their abilities to change the surface tension of solutions. In addition, compounds with the recognition motif, not those without such motif, can inhibit cytotoxicity of Abeta in cell culture probably by decreasing the amount of toxic Abeta oligomers. These results indicate that recognition domain and solvent effect should be considered as important factors when designing molecules to target Abeta aggregation.
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http://dx.doi.org/10.1016/j.peptides.2009.04.012DOI Listing
July 2009

Sequestration of copper from beta-amyloid promotes selective lysis by cyclen-hybrid cleavage agents.

J Biol Chem 2008 Nov 26;283(46):31657-64. Epub 2008 Aug 26.

Department of Chemistry, Tsinghua University, Beijing 100084, China.

Decelerated degradation of beta-amyloid (Abeta) and its interaction with synaptic copper may be pathogenic in Alzheimer disease. Recently, Co(III)-cyclen tagged to an aromatic recognition motif was shown to degrade Abeta in vitro. Here, we report that apocyclen attached to selective Abeta recognition motifs (KLVFF or curcumin) can capture copper bound to Abeta and use the Cu(II) in place of Co(III) to become proteolytically active. The resultant complexes interfere with Abeta aggregation, degrade Abeta into fragments, preventing H2O2 formation and toxicity in neuronal cell culture. Because Abeta binds Cu in amyloid plaques, apocyclen-tagged targeting molecules may be a promising approach to the selective degradation of Abeta in Alzheimer disease. The principle of copper capture could generalize to other amyloidoses where copper is implicated.
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http://dx.doi.org/10.1074/jbc.M804722200DOI Listing
November 2008

O-GlcNAcylation modulates the self-aggregation ability of the fourth microtubule-binding repeat of tau.

Biochem Biophys Res Commun 2008 Oct 29;375(1):59-62. Epub 2008 Jul 29.

Department of Chemistry, Beihua University, Jilin 132013, PR China.

In Alzheimer's disease (AD), tau protein is abnormally hyperphosphorylated and aggregated into paired helical filaments (PHFs). It was discovered recently that tau is also O-GlcNAcylated in human brains. And O-GlcNAcylation may regulate phosphorylation of tau in a site-specific manner. In this work, we focused on the fourth microtubule-binding repeat (R4) of tau, which has an O-GlcNAcylation site-Ser356. The aggregation behavior of this repeat and its O-GlcNAcylated form was investigated by turbidity, precipitation assay and electron microscopy. In addition, conformations of these two peptides were analyzed with circular dichroism (CD). Our results revealed that O-GlcNAcylation at Ser356 could greatly slow down the aggregation speed of R4 peptide. This modulation of O-GlcNAcylation on tau aggregation implies a new perspective of tau pathology.
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http://dx.doi.org/10.1016/j.bbrc.2008.07.101DOI Listing
October 2008

TiO2 nanoparticles promote beta-amyloid fibrillation in vitro.

Biochem Biophys Res Commun 2008 Aug 20;373(2):315-8. Epub 2008 Jun 20.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, China.

Alzheimer's disease (AD) is the most common neurodegenerative disease in the world. The pathogenesis of AD is associated with beta-amyloid (Abeta) fibrillation. Nanoparticles have large surface area and can access the brain. But no investigation has been made to study the relationship between nanoparticles and AD. In our study, we observed Abeta fibril formation in the presence of six kinds of nanoparticles and found that TiO2 nanoparticles can promote Abeta fibrillation by shortening nucleation process, which is the key rate-determining step of fibrillation. Hereby the interaction between Abeta and nanoparticles may contribute to AD etiology.
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http://dx.doi.org/10.1016/j.bbrc.2008.06.035DOI Listing
August 2008

Prevention and promotion effects of apolipoprotein E4 on amylin aggregation.

Biochem Biophys Res Commun 2008 Apr 1;368(2):414-8. Epub 2008 Feb 1.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China.

The misfolding of islet amyloid polypeptide (IAPP, amylin) results in the formation of islet amyloid, which is one of the most common pathological features of type 2 diabetes (T2D). Amylin, a 37-amino-acid peptide co-secreted with insulin and apolipoprotein E (ApoE) from the beta-cells of pancreatic islets, is thought to be responsible for the reduced mass of insulin-producing beta-cells. However, neither the relationship between amylin and ApoE nor the biological consequence of amylin misfolding is known. Here we have characterized the interaction between ApoE4 and amylin in vitro. We found that ApoE4 can strongly bind to amylin, and insulin can hardly inhibit amylin-ApoE binding. We further found that amylin fibrillization can be prevented by low concentration of ApoE4 and promoted by high concentration of ApoE4. Taken together, we propose that under physiological conditions ApoE4 efficiently binds and sequesters amylin, preventing its aggregation, and in T2D the enhanced ApoE4-amylin binding leads to the critical accumulation of amylin, facilitating islet amyloid formation.
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http://dx.doi.org/10.1016/j.bbrc.2008.01.103DOI Listing
April 2008

Copper (II) modulates in vitro aggregation of a tau peptide.

Peptides 2007 Nov 31;28(11):2229-34. Epub 2007 Aug 31.

Key Laboratory of Bioorganic Phosphorus Chemistry & Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing 100084, PR China.

Copper (II) has been implicated in the pathology of Alzheimer's disease (AD) for the impaired homeostatic mechanism found in the brains of AD patients. Here we studied the binding properties of Cu(II) with the first microtubule-binding repeat, encompassing residues 256-273 of the human tau441 sequence. Additionally, the effect of Cu(II) on the assembly of this repeat was also investigated. Our results indicate that Cu(II) can bind to this repeat with His(268) involved and has an inhibiting effect on the in vitro aggregation of this repeat. This work provides new insight into the role of Cu(II) in Alzheimer's disease.
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http://dx.doi.org/10.1016/j.peptides.2007.08.022DOI Listing
November 2007

Phosphorylation modulates the local conformation and self-aggregation ability of a peptide from the fourth tau microtubule-binding repeat.

FEBS J 2007 Oct 24;274(19):5012-20. Epub 2007 Aug 24.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Tsinghua University, Beijing, China.

Phosphorylation of tau protein modulates both its physiological role and its aggregation into paired helical fragments, as observed in Alzheimer's diseased neurons. It is of fundamental importance to study paired helical fragment formation and its modulation by phosphorylation. This study focused on the fourth microtubule-binding repeat of tau, encompassing an abnormal phosphorylation site, Ser356. The aggregation propensities of this repeat peptide and its corresponding phosphorylated form were investigated using turbidity, thioflavin T fluorescence and electron microscopy. There is evidence for a conformational change in the fourth microtubule-binding repeat of tau peptide upon phosphorylation, as well as changes in aggregation activity. Although both tau peptides have the ability to aggregate, this is weaker in the phosphorylated peptide. This study reveals that both tau peptides are capable of self-aggregation and that phosphorylation at Ser356 can modulate this process.
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http://dx.doi.org/10.1111/j.1742-4658.2007.06018.xDOI Listing
October 2007

Hydrogen peroxide can be generated by tau in the presence of Cu(II).

Biochem Biophys Res Commun 2007 Jun 7;358(2):661-5. Epub 2007 May 7.

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, Beijing, PR China.

Alzheimer's disease has been closely related with oxidative stress, which might be responsible for the dysfunction or death of neuronal cells that contributes to disease pathogenesis. Impaired copper homeostasis makes contribution to the oxidative stress and consequently to several neurodegenerative conditions. Inappropriate binding of Cu(II) to cellular proteins are currently being explored as sources of pathological oxidative stress in several neurodegenerative disorders. Here we report that a fragment of tau protein possesses copper reduction activity and initiates the copper-mediated generation of hydrogen peroxide. The tau peptide was found to be oxidized to form disulfide bond-linked dimer. The hydrogen peroxide generated was quantified by TCEP/DTNB (tris(2-carboxyethyl) phosphine hydrochloride/5,5'-dithio-bis(2-nitrobenzoic acid). Since the copper reduction capacity and the generation of hydrogen peroxide were believe to be a major toxicological pathway of Abeta peptide, the functional similarity shared by tau and Abeta implies a new perspective of tau pathology.
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http://dx.doi.org/10.1016/j.bbrc.2007.04.191DOI Listing
June 2007

Characterization of copper binding to the peptide amyloid-beta(1-16) associated with Alzheimer's disease.

Biopolymers 2006 Sep;83(1):20-31

Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology (Ministry of Education), Department of Chemistry, Tsinghua University, 100084 Beijing, China.

Amyloid-beta peptide (Abeta) is the principal constituent of plaques associated with Alzheimer's disease (AD) and is thought to be responsible for the neurotoxicity associated with the disease. Copper binding to Abeta has been hypothesized to play an important role in the neruotoxicity of Abeta and free radical damage, and Cu2+ chelators represent a possible therapy for AD. However, many properties of copper binding to Abeta have not been elucidated clearly, and the location of copper binding sites on Abeta is also in controversy. Here we have used a range of spectroscopic techniques to characterize the coordination of Cu2+ to Abeta(1-16) in solution. Electrospray ionization mass spectrometry shows that copper binds to Abeta(1-16) at pH 6.0 and 7.0. The mode of copper binding is highly pH dependent. Circular dichroism results indicate that copper chelation causes a structural transition of Abeta(1-16). UV-visible absorption spectra suggest that three nitrogen donor ligands and one oxygen donor ligand (3N1O) in Abeta(1-16) may form a type II square-planar coordination geometry with Cu2+. By means of fluorescence spectroscopy, competition studies with glycine and L-histidine show that copper binds to Abeta(1-16) with an affinity of Ka approximately 10(7) M(-1) at pH 7.8. Besides His6, His13, and His14, Tyr10 is also involved in the coordination of Abeta(1-16) with Cu2+, which is supported by 1H NMR and UV-visible absorption spectra. Evidence for the link between Cu2+ and AD is growing, and this work has made a significant contribution to understanding the mode of copper binding to Abeta(1-16) in solution.
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http://dx.doi.org/10.1002/bip.20523DOI Listing
September 2006
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