METABOLISM OF POLY-BETA-HYDROXYBUTYRATE .I. PURIFICATION COMPOSITION AND PROPERTIES OF NATIVE POLY-BETA-HYDROXYBUTYRATE GRANULES FROM BACILLUS MEGATERIUM

Native poly-β-hydroxybutyrate granules from Bacillus megaterium have been purified and their composition and properties have been studied. The granules are composed of approximately 98% poly-β- hydroxybutyrate, 2% protein, and small amounts of lipid. The lipid components comprise an unidentified acetone-soluble compound and a single phospholipid identified as phosphatidic acid. The purified granules are surrounded by a membrane coat and possess similar properties to those previously reported for crude preparations. The poly-β-hydroxybutyrate synthetase remains firmly bound to the granules throughout the purification. The KM for the synthetase is 9.25 × 10−5 m and its pH optimum is 7.5. The synthetase is inhibited by low levels of N-ethylmaleimide and p-mercuribenzoate. © 1968, American Chemical Society. All rights reserved.