Stimulation of Transport into Escherichia coli Membrane Vesicles by Internally Generated Reduced Nicotinamide Adenine Dinucleotide

Abstract

Membrane vesicles containing internal alcohol dehydrogenase and nicotinamide adenine dinucleotide (NAD) were prepared from Escherichia coli ML308-225. Upon the addition of ethanol, these vesicles respired and transported several amino acids. Transport rates driven by internally generated reduced NAD (NADH) were about 60 to 80% of that stimulated by d-lactate. This transport was inhibited by cyanide and anaerobiosis. Ferricyanide, a nonpermeable electron acceptor, inhibited transport stimulated by external NADH, but not that stimulated by internally generated NADH.