HIGH-SULFUR PROTEINS FROM ALPHA-KERATINS .2. ISOLATION AND PARTIAL CHARACTERIZATION OF PURIFIED COMPONENTS FROM MOUSE HAIR

Abstract

The paper continues the study of the reduced and S-carboxymethylated high-sulfur proteins from mouse hair. Fractions were obtained in a substantially purified form by fractional precipitation with ammonium sulfate at pH 6, followed by ion exchange chromatography on cellulose phosphate at pH 2.6. Approximately 80% by weight of the high-sulfur proteins fall into the ultra-high-sulfur category (carboxymethylcysteine content greater than 26 residues/100 residues), and they cover a MW range of 17,000-28,000. The components show a remarkable diversity in amino acid composition; for example, the contents of arginine and glycine each vary by about 3:1. The remainder of the proteins contain 17-20 residues/100 residues of carboxymethylcysteine, are smaller in size (MW 11,500), and also show great diversity in overall amino acid composition. Molecular weights were determined by chromatography on controlled-pore glass and confirmed by gel filtration on Sephadex G-100 and Sepharose 6B. A comparison of the results suggests that the values obtained should be reliable to within 10%.