LACTATE AND GLUCOSE OXIDATION SYSTEMS IN ACETOBACTER SUBOXYDANS

1. From a strain of Acelobacter suboxydans, a glucose and a lactic enzyme were obtained in cell-free states. The lactic enzyme shows as strong activity as the glucose etvcyme but is more stable than the latter toward various purification procedures: both are sensitive to high temperature treatment. Activities of the two enzymes and the MICHAELIS constants of the glucose enxyme were determined under both aerobic and anaerobic conditions. 2. Carbon monoxide inhibits the oxygen-uptake in both glucose and lactate oxidation. WARBURG'S distribution constant for lactate oxidation is 6.7. These results suggest the participation of an heme enzyme in the oxidation system. Effects of copper reagents, narcotics and PCMB were also ex-amined. 3. The dehydrogenase activities (reduction of dye) of the enzymes are more sensitive to high temperature than the cor-responding activities in oxygen-uptake. 4. By combining a dehydrogenase preparation which has lost its oxygen-absorbing activity through acetone treatment, with a heated extract, a partial recovery of oxygen-uptake can be realized in lactate oxidation. 5. L-Cysteine is utilized as hydrogen donor by the bacterium. This oxidative reaction, unlike the oxidation of lactate, is not inhibited by surface active reagents. Several kinds of lactic and glucose oxidizing enzymes are known; among these a DPN-reducing lactic enzyme of animal tissue was first prepared in crystalline form (i) and later a crystalline lactic flavin enzyme from yeast (2). The enzyme of the former type is an essential factor in the lactic fermentation and glycolysis in animals and such enzymes has also been found in some anaerobic or facultative anaerobic bacteria, e. g. Escherichia coli (3). Abbreviations: BPB, bromphenol blue; PCMB, p-chloromercuribenzoic aci