Transport of sugars and amino acids in bacteria. XV. Comparative studies on the effects of various energy poisons on the oxidative and phosphorylating activities and energy coupling reactions for the active transport systems for amino acids in E. coli.

The effects of various energy poisons on oxidation of respiratory substrate, synthesis of cellular ATP, and energy transformation reaction in intact Escherichia coli cells were studied systematically. Various mutants were, therefore, used in which specific functions in the energy-transducing reactions were defective or altered. The energy poisons examined were: sodium azide. DPPA and azidebenzenes which are inhibitors of respiratory-chain phosphorylation, SF6847, and CCCP which are known to be uncouplers, zinc sulfate which is an inhibitor for certain dehydrogenases, and sodium arsenate and sodium fluoride which are inhibitors of glycolytic synthesis of ATP. The preferential inhibitions occurred in the oxidation reactions with certain respiratory substrates by energy poisons used. DPPA inhibited glycerol oxidation much more strongly than succinate oxidation. However, DPPA could inhibit the oxidation of both glycerol 3-phosphate and succinate by membrane fraction strongly while the oxidation of NADH and D-lactate slightly. It inhibited glycerol 3-phosphate dehydrogenase [EC 1.1.2.1] strongly as well as succinate dehydrogenase [EC 1.3.99.1],.but not D-lactate dehydrogenase of membrane fraction. MAB and other azidebenzene derivatives inhibited succinate oxidation preferentially. SF6847 and CCCP inhibited succinate oxidation strongly, while sodium azide inhibited it weakly and these three poisons were less inhibitory for glycerol oxidation. DPPA, sodium azide, SF6847, and CCCP inhibited the synthesis of ATP coupled with respiration but not with glycolysis. Zinc sulfate inhibited the cellular ATP synthesis coupled with either respiration or glycolysis.