In vitro non-enzymatic glycation and formation of browning products in the bovine lens alpha-crystallin.

Calf lens LMW alpha-crystallin was glycated by incubating with various sugars (glucose, glucose-6-P and ribose) for 21 days. All sugars induced disulfide formation, but ribose also produced higher molecular weight cross-linked species. The ribocated protein turned yellow in color and had a strong blue fluorescence (Ex/Em = 370/450 nm) typical for a browning product. The chromophore of the browning product showed a new circular dichroism (CD) band at 320-330 nm. Conformational study indicated that the browning reaction destablized protein and may play a significant role in protein aggregation and insolubilization.