title: Chaperone-like activity of a synthetic peptide toward oxidized gamma-crystallin.
abstract: alphaA-Crystallin can function like a molecular chaperone. We recently reported that the alphaA-crystallin sequence, KFVIFLDVKHFSPEDLTVK (peptide-1, residues 70-88) by itself possesses chaperone-like (anti-aggregating) activity during a thermal denaturation assay. Based on the above data we proposed that the peptide-1 sequence was the functional site in alphaA-crystallin. In this study we investigated the specificity of peptide-1 against gamma-crystallin aggregation in the presence of H2O2 and CuSO4. Peptide-1 was able to completely protect against the oxidation-induced aggregation of gamma-crystallin. Removal of N-terminal Lys or the replacement of Lys with Asp (DFVIFLDVKHFSPEDLTVK, peptide-2) did not alter the anti-aggregation property of peptide-1. However, deletion of KF residues from the N-terminus of peptide-1 resulted in a significant loss of its anti-aggregation property. Bio-gel P-30 size-exclusion chromatography of gamma-crystallin incubated with peptide-2 under oxidative conditions revealed that a major portion of the peptide elutes in the void volume region along with gamma-crystallin, suggesting the binding of the peptide to the protein. Peptide-1 and -2 were also able to prevent the UV-induced aggregation of gamma-crystallin. These data indicate that the same amino acid sequence in alphaA-crystallin is likely to be responsible for suppressing the heat-denatured, oxidatively modified and UV-induced aggregation of proteins.
authors.affiliation: Institute and Department of Biochemistry, University of Missouri, Columbia, USA.
authors.forename: R S
authors.initials: RS
authors.lastname: Kumar
authors.forename: K K
authors.initials: KK
authors.lastname: Sharma
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D003459:Crystallins / Q000737:chemistry* / Q000528:radiation effects; D006360:Heat-Shock Proteins / Q000737:chemistry; D018832:Molecular Chaperones / Q000737:chemistry*; D008969:Molecular Sequence Data; D010084:Oxidation-Reduction; D010446:Peptide Fragments / Q000138:chemical synthesis / Q000737:chemistry*; D011485:Protein Binding; D011487:Protein Conformation / Q000528:radiation effects; D017433:Protein Structure, Secondary; D014466:Ultraviolet Rays / Q000009:adverse effects
chemical_list: D003459:Crystallins; D006360:Heat-Shock Proteins; D018832:Molecular Chaperones; D010446:Peptide Fragments