title: Evaluation of structure, chaperone-like activity and protective ability of peroxynitrite modified human α-Crystallin subunits against copper-mediated ascorbic acid oxidation.
abstract: The copper-catalyzed oxidation of ascorbic acid (ASA) to dehydroascorbate (DHA) and hydrogen peroxide plays a central role in pathology of cataract diseases during ageing and in diabetic patients. In the current study, the structural feature, chaperone-like activity and protective ability of peroxynitrite (PON) modified αA- and αB-Crystallin (Cry) against copper-mediated ASA oxidation were studied using different spectroscopic measurements and gel mobility shift assay. Upon PON modification, additional to protein structural alteration, the contents of nitrotyrosine, nitrotryptophan, dityrosine and carbonyl groups were significantly increased. Moreover, αB-Cry demonstrates significantly larger capacity for PON modification than αA-Cry. Also, based on the extent of PON modification, these proteins may display an improved chaperone-like activity and enhanced protective ability against copper-mediated ASA oxidation. In the presence of copper ions, chaperone-like activity of both native and PON-modified α-Cry subunits were appreciably improved. Additionally, binding of copper ions to native and PON-modified proteins results in the significant reduction of their solvent exposed hydrophobic patches. Overall, the increase in chaperone-like activity/ASA protective ability of PON-modified α-Cry and additional enhancement of its chaperoning action with copper ions appear to be an important defense mechanism offered by this protein.
authors.affiliation: Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Ghahramani
authors.affiliation: Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran. Electronic address: ryousefi@shirazu.ac.ir.
authors.forename: Reza
authors.initials: R
authors.lastname: Yousefi
authors.affiliation: Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran.
authors.forename: Kazem
authors.initials: K
authors.lastname: Khoshaman
authors.affiliation: Protein Chemistry Laboratory (PCL), Department of Biology, College of Sciences, Shiraz University, Shiraz, Iran.
authors.forename: Sogand Sasan
authors.initials: SS
authors.lastname: Moghadam
authors.affiliation: Bach Institute of Biochemistry, Research Center of Biotechnology of the Russian Academy of Sciences, 33, bld. 2 Leninsky Ave., Moscow 119071, Russia.
authors.forename: Boris I
authors.initials: BI
authors.lastname: Kurganov
mesh_terms: D000818:Animals; D001205:Ascorbic Acid / Q000378:metabolism*; D002417:Cattle; D003300:Copper / Q000378:metabolism*; D006801:Humans; D008958:Models, Molecular; D009690:Nucleic Acid Conformation; D030421:Peroxynitrous Acid / Q000737:chemistry*; D038202:alpha-Crystallin A Chain / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D038203:alpha-Crystallin B Chain / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*
chemical_list: D038202:alpha-Crystallin A Chain; D038203:alpha-Crystallin B Chain; D030421:Peroxynitrous Acid; D003300:Copper; D001205:Ascorbic Acid
keywords: Ascorbic acid; Chaperone activity; Copper ion; Peroxynitrite; α-Crystallin