Some Properties of the Succinate Dehydrogenase of Escherichia coii

Abstract

Succinate dehydrogenase (SDH) was found in a cell envelope fraction from E. coli. If the enzyme preparation was made in 0.01 M phosphate buffer, pH 7.5, with or without 0.025 M succinate, or in 0.01 M Tris buffer, the activity of the enzyme could be markedly increased by heating the enzyme at 38° for 15 min with 15 mM succinate. Activation did not occur at 0°. If the enzyme preparation was made in Tris buffer containing succinate the enzyme was found to be fully activated. SDH was obtained in a low molecular weight form by extracting an acetone powder of whole cells with buffer. This enzyme had a molecular weight of about 100 000 and could be purified free from cytochrome.