Glycation of crystalline in lenses from aging and diabetic individuals

Abstract

Water-soluble crystallins were obtained from clear human lenses of different age(4–81-year-olds) and lenses of individuals showing senile and diabetic cataracts. Levels of early glycation products were high in the high molecular weight material (HM) and the α-crystallin fractions, compared with β and γ-crystallins. This difference becomes more prominent upon aging. The content of total early glycation products in HM and α-crystallin increases clearly with age, whereas levels remain relatively constant in the β- and α-crystallins. There is an elevation of early products in cataractous lenses from diabetic individuals compared with those suffering from senile cataract. Specific non-tryptophan fluorescence (excitation/emission wavelengths 370/440 nm), used as an indicator for late glycation products, increased dramatically with age and was 2-fold higher in the diabetic subjects. Levels of fluorescence decreased in the order HM > α- > b > γ-crystallins. The results suggest an increase in glycation rate in α-crystallin as a result of aging and diabetes, while the rate of glycation of β- and γ-crystallins remains almost constant.