Heterogeneity of human cataractous and normal lens γ-crystallins

Abstract

Four low molecular weight proteins were isolated from human cataractous lenses (i.e. cortical, nuclear and posterior subcapsular cataracts) and human normal lens by gel filtration and refiltration of Sephadex G-75 superfine, respectively. According to a previous report, in human normal lens, peak 1 corresponded to β s -crystallin, peak 2 to heavy molecular weight γ -crystallin ( γ H) and peak 3 and 4 to light molecular weight γ -crystallins ( γ L 2 ). Molecular weights of these major proteins were 28000 ( β s ), 24000 ( γ H), 20000 ( γ L 1 ) and 11000 ( γ L 2 ), respectively. Aggregation was observed in the prominent peak of γ H- and the γ L 2 -crystallins of human cataractous and normal lenses. Human cataractous and normal γ -crystallin showed a high degree of charge heterogeneity, while the γ H has faster mobility than γ L 1 - and γ L 2 -crystallins. Isoelectric focusing of human cataractous and normal lens low molecular weight proteins had similar heterogeneous protein zones. However, human cataractous lens low molecular weight proteins revealed increased staining intensity in the neutral to acidic pH range relative to normal lens.