Please use this identifier to cite or link to this item:
Title: Structure/function studies of dogfish α-crystallin, comparison with bovine α-crystallin
Authors: Ghahghaei, A
Rekas, A
Carver, JA
Augusteyn, RC
Keywords: Crystalline lens
Amino acids
Issue Date: 20-Nov-2009
Publisher: National Center for Biotechnology Information
Citation: Ghahghaei, A., Rekas, A., Carver, J. A., & Augusteyn, R. C. (2009). Structure/function studies of dogfish α-crystallin, comparison with bovine α-crystallin. Molecular Vision, 15(256-59), 2411-2420.
Abstract: Purpose: α-Crystallin is the major protein of the mammalian lens where it contributes to the refractive properties needed for vision and possibly to the stability of the tissue. The aim of this study was to determine whether the properties of α-crystallin have changed during the course of evolution. Methods: Dogfish α-crystallin, which appeared over 420 million years ago, has been contrasted with bovine α-crystallin, which emerged around 160 million years later, by comparing their sizes, the microenvironments of their cysteine and tryptophan residues, their chaperone-like activities and the flexibility of their COOH-terminal extensions. Results: Dogfish α-crystallin consists of α A- and α B-polypeptides, in a 1: 5 ratio, and has a molecular mass of around 400 kDa. By contrast, the bovine protein is around 600-800 kDa in mass and has a 3: 1 subunit ratio. Cysteine residues in the proteins were equally accessible to reaction with 5,5'-dithiobis-(2-nitrobenzoic acid). Quenching of fluorescence with acrylamide indicated tryptophan residues in the two proteins were in similar environments. The chaperone activity of dogfish α-crystallin was comparable to that of bovine α-crystallin in preventing the heat-induced precipitation of β(L)-crystallin but the dogfish protein was three times more effective at preventing insulin precipitation after reduction at 37 degrees C. H-1 nuclear magnetic resonance spectroscopic studies showed that the last 17 amino acids of the dogfish α B polypeptide (V162-K178) have great conformational flexibility, are highly exposed to solvent and adopt little ordered conformation. This is comparable to, but slightly longer in length, than the COOH-terminal extension observed in mammalian alpha-crystallins. Conclusions: The structure and properties of α-crystallin have changed relatively little during the evolutionary period from the emergence of sharks and mammals. © US National Library of Medicine National Institutes of Health
Gov't Doc #: 1263
ISSN: 1090-0535
Appears in Collections:Journal Articles

Files in This Item:
File Description SizeFormat 
GHAHGHAEI_Structure_Function_Dogfish_Comparison_Bovine_2009_11.pdf925.64 kBAdobe PDFThumbnail

Items in DSpace are protected by copyright, with all rights reserved, unless otherwise indicated.