Variation in proportion and molecular weight of native crystallins from single human lenses upon aging and formation of nuclear cataract

Abstract

Extracts of water-soluble proteins from cortex and nucleus of single human lenses have been analyzed by high-pressure gel permeation chromatography in combination with a size- and a concentration-sensitive detector. Using this rapid and accurate method, changes in molecular weight and proportion of the native crystallins upon aging and formation of nuclear cataract are observed. In the range from 30 to about 40 years the γ-crystallin content of normal lenses increases and that of α-crystallin decreases; over 40 years the level of γ-crystallin decreases and that of α-crystallin remains constant in the cortex (11%) as well as in the nucleus (1–2%). These changes are accompanied by an increase in the water-insoluble fraction. With progressing nuclear cataract an increase in β 3- and a drastic decrease in γ-crystallin content, especially in the nucleus, are accompanied by a steep increase in the water-insoluble fraction. The molecular weights of the crystallins do not change significantly, except that of α- and β 1-crystallin which show an increase with age.