Human alpha-crystallin-III isolation and characterization of protein from normal infant lenses and old lens peripheries.

Alpha-crystallin isolated from the peripheries of old normal or cataractous lenses appears to be identical, consisting of eleven polypeptides, five B, and six A chains. In contrast, alpha-crystallin isolated from normal six-week-old human lenses has only three major polypeptides, corresponding to B1, A1, and A2 of the old human lens protein as well as small amounts of some of the other components. Comparisons with bovine alpha-crystallin are also reported. Based on gel filtration experiments with Bio-Gel A-1.5m, two distinct populations of alpha-crystallin were found in old lens periphery, one containing species greater than 1.5 X 10(6) daltons and another of approximately 9 X 10(5) daltons. In the cataract preparations, the higher molecular weight fraction is predominant. This fraction is not present in young lenses.