Régulation de la biosynthèse et de la fonction des D- et L-lactate-déshydrogénases chez Aerobacter aerogenes

Abstract

Summary 1. Aerobacter aerogenes possesses two stereospecific lactate dehydrogenases ( D - and L -lactate dehydrogenases) which permit the organism to utilize D - and L -lactate as energy and carbon sources, under aerobic conditions. 2. The principal properties of these enzymes are described. 3. Under aerobic conditions, glucose represses the formation of the L -lactate dehydrogenase and inhibits the activity of the D -lactate dehydrogenase. Both of these effects can be observed in the presence of other carbon sources. Glucose does not repress the formation of the D -lactate dehydrogenase and does not inhibit the activity of the L-lactate dehydrogenase. 4. The D -lactate dehydrogenase is synthesized whatever the growth conditions. 5. The formation of the L -lactate dehydrogenase requires the presence of oxygen and one of the antipodes of lactate. The mechanism of its regulation seems to lack any stereospecificity. 6. Our observations have been extended to include other species of facultative anaerobes.