Isolation of Non‐identical Polypeptide Chains of Α‐crystallin

Abstract

a-Crystallin-a water-soluble lens proteiii-was disociated into subunits by means of urea treatment at pH 3. The dissociated protein was resolved into three distinct polypeptide species by chromatography on SE-Sephadex columns at p H 3.2 equilibrated with 7 M urea.In the presence of urea the isolated polypeptides, designated as I-a, I-b, and II, have different electrophoretic mobilities at acid and alkaline pH. It could be demonstrated that two cysteine residues are present in polypeptide I-a whereas cysteine is absent in polypeptide II. Moreover, amino-acid analysis reveals that both polypeptides have a