Effects of glycation on human £^D-crystallin proteins by different glycation-inducing agents

Abstract

Human £^D-crystallin (H£^D-crystallin), a major protein component of the human eye lens, is associated with the development of juvenile- and mature-onset cataracts. Evidence suggests that nonenzymatic protein glycation plays an important role in the aetiology of cataract and diabetic sequelae. This research compared the effects of various glycation modifiers on H£^D-crystallin aggregation, by treating samples of H£^D-crystallin with ribose, galactose, or methylglyoxal using several biophysical techniques. To measure advanced glycation end products, an N£`-(carboxyethyl)lysine enzyme-linked immunosorbent assay was performed on the glycating agent-treated H£^D-crystallin samples. Fructosamine production detection was performed for both ribose-treated and galactose-treated samples. Methylglyoxal-treated samples had the highest level of aggregation and the greatest extent of unfolding, and upon incubation for a minimum of 12 days, exhibited a marked enhancement in the amount of N£`-(carboxyethyl)lysine. The molecular profiles and morphological features of the glycated samples were highly correlated to the type of glycation agent used. These findings highlight a close connection between the type of glycation modifier and the various aggregation species that form. Thus, these results may facilitate deciphering of the molecular mechanism of diabetic cataractogenesis. ? 2018