THE NATURE OF THE MULTIPLE FORMS OF BOVINE THIOL: PROTEIN DISULFIDE OXIDOREDUCTASE

Abstract

Preparations of thiol:protein disulfide oxidoreductase from bovine liver were previously shown to be homogeneous by polyacrylamide gel electrophoresis, sedimentation equilibrium centrifugation and NH2-terminal analysis. When the enzyme was subjected to prolonged storage at -20.degree., freeze-thawing, or heating at 60.degree., at least 1 new protein species was observed using polyacrylamide gel electrophoresis. The new protein results from dimerization of the enzyme. The dimer consisted of 2 monomers held together by an intermolecular disulfide bond. The formation of this dimer can be reversed and partially prevented by thiols.