[Thioltransferase and thioredoxin system in cataract].

The lens depends on a balanced redox state and SH/-S-S- ratio for maintaining its transparency. The endogenous high level of glutathione (GSH) and its intrinsic repair enzymes are very important lines of defense for the health of the lens. However, ageing lenses or cataract lenses show an extensively diminished size of GSH pool. The research in thioltransferase (TTase) and thioredoxin (Trx) system show TTase can specifically dithiolate protein-S-S-glutathione and restore protein free SH groups for proper enzymatic or protein functions; Trx system can dithiolate protein disulfides and thus is an extremely important regulator for redox homeostasis in the cells. The two enzymes may work synergistically to repair thiols in lens proteins and enzymes and maintain the function of the lens effectively.