Subunit structure and composition of oat seed globulin

Abstract

Oat (Avena sativa L.) seed globulin was extracted from ground caryopses with 1 m NaCl, 0.05 m Tris(hydroxymethyl)aminoethane (pH 8.5) at room temperature. The globulin had a sedimentation constant of 12.1, and a molecular weight of 322,000, as determined by analytical ultracentrifugation. The globulin could be separated into two major subunits by sodiumdodecyl sulfate polyacrylamide gel electrophoresis. Molecular weights of the subunits were 21,700 (alpha) and 31,700 (beta), and they were present in equimolar amounts. A subunit model of 6alpha and 6beta per molecule of globulin is proposed. Amino acid analysis indicated that the alpha subunit contained more basic amino acids and aspartic acid/asparagine but less glutamic acid/glutamine and glycine than the beta subunit.