Localization of Enzymes in Mycoplasma

Abstract

Cells of eight parasitic and two saprophytic Mycoplasma strains were lysed by use of osmotic shock, and the membranes were separated from the soluble fraction by use of differential centrifugation. Cell fractions were tested for reduced nicotinamide adenine dinucleotide (NADH2) oxidase, reduced nicotinamide adenine dinucleotide phosphate (NADPH2) oxidase, glucose-6-phosphate dehydrogenase, adenosine triphosphatase, ribonuclease, and deoxyribonuclease activities. Adenosine triphosphatase was confined to the membrane fraction of all Mycoplasma strains. The NADH2 oxidase activity was associated with the membranes of the saprophytic M. laidlawii and with the soluble fraction of the parasitic Mycoplasma strains. NADPH2 oxidase activity was detected only in the soluble fraction of the parasitic strains. Glucose-6-phosphate dehydrogenase was demonstrated only in the soluble fraction of M. laidlawii. Ribonuclease activity was found usually in both membrane and soluble fractions, but was generally higher in the membrane fraction. In the human and bovine Mycoplasma strains, deoxyribonuclease activity could not be demonstrated in the soluble fraction; in the remaining strains, activity was highest in the soluble fraction. Dissolution of M. laidlawii strain-B membranes by sodium deoxycholate significantly increased membrane-NADH2 oxidase and adenosine triphosphatase activities.