ENZYME DISTRIBUTION IN MEMBRANE, CYTOPLASM, AND NUCLEAR FRACTIONS FROM PSEUDOMONAS FLUORESCENS

Abstract

Burrous , S. E. (University of Illinois, Urbana) and W. A. Wood . Enzyme distribution in membrane, cytoplasm, and nuclear fractions from Pseudomonas fluorescens . J. Bacteriol. 84: 364–369. 1962.—A procedure is described for fractionation of Pseudomonas fluorescens A3.12 by controlled rupture of spheroplasts and fractional centrifugations to yield cytoplasm, membrane, and deoxyribonucleic acid (DNA) fractions with low cross contamination and little loss of enzymatic activity. Assays for the content of a number of oxidative and nonoxidative enzymes revealed that: (i) little activity is present in the DNA fraction; (ii) only reduced diphosphopyridine nucleotide oxidase is found exclusively in the membranes; (iii) phosphohexosisomerase and probably transketolase and glucose-6-phosphate dehydrogenase are found exclusively in the cytoplasm; and (iv) the remaining five enzymes studied were found in both fractions. In contrast to earlier reports of gluconic dehydrogenase being membrane-bound and 2-keto-3-deoxy-6-phosphogluconate aldolase being soluble in sonic extracts, this procedure produced partly soluble gluconic dehydrogenase and partly membrane-associated 2-keto-3-deoxy-6-phosphogluconate aldolase.