Glycation of crystallins in lenses from aging and diabetic individuals.
Water-soluble crystallins were obtained from clear human lenses of different age (4-81-year-olds) and lenses of individuals showing senile or diabetic cataracts. Levels of early glycation products were high in the high molecular weight material (HM) and the alpha-crystallin fractions, compared with beta- and gamma-crystallins. This difference becomes more prominent upon aging. The content of total early glycation products in HM and alpha-crystallin increases clearly with age, whereas levels remain relatively constant in the beta- and gamma-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 > alpha- > beta- > gamma-crystallins. The results suggest an increase in glycation rate in alpha-crystallin as a result of aging and diabetes, while the rate of glycation of beta- and gamma-crystallins remains almost constant.
van Boekel
M A
MA
Department of Biochemistry, University of Nijmegen, The Netherlands.
Hoenders
H J
HJ
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000378:metabolism*; D002386:Cataract / Q000209:etiology / Q000378:metabolism*; D002648:Child; D002675:Child, Preschool; D003459:Crystallins / Q000378:metabolism*; D048909:Diabetes Complications; D003920:Diabetes Mellitus / Q000378:metabolism*; D006023:Glycoproteins / Q000032:analysis*; D006801:Humans; D007908:Lens, Crystalline / Q000737:chemistry*; D008875:Middle Aged; D010084:Oxidation-Reduction; D012995:Solubility; D013050:Spectrometry, Fluorescence
D003459:Crystallins; D006023:Glycoproteins