Lanthionine, a protein cross-link in cataractous human lenses.

Oxidative processes are suggested to be a main cause of the covalent cross-linking of lenticular proteins. For a major part these cross-links are disulfides (cystine). With progression of nuclear cataract, cystine may be oxidized further to cysteic acid. Another oxidative degradation product of cystine is the symmetric thioether lanthionine. In this study, we clearly demonstrate that lanthionine is a protein cross-link of cataractous human lenses. Possible mechanisms of its formation are discussed.