Vitamin C induced oxidation of eye lens gamma crystallins

Crystallins are long-lived proteins of the eye lens that have specific structures that maintain lens transparency. Lens crystallins are known to undergo changes with age that include oxidation. Oxidation may contribute to cataract development. In this study the effect of metal-catalysed oxidation of vitamin C (ascorbate) on gamma-crystallins was investigated based on polyacrylamide gel electrophoresis and electrospray mass spectrometry. Cross-linking, aggregation and denaturation occurred when two members of the gamma-crystalline family, gamma B and gamma S, were challenged with copper (II) and ascorbate. These proteins form a dimer, with copper alone or with the addition of ascorbate, which may be an early marker of oxidation. It was found that alpha-ketoglutarate and pyruvate were very effective in the inhibition of oxidation. (C) Societe francaise de biochimie et biologie moleculaire/Elsevier, Paris.