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Energy-coupling mechanisms under aerobic and anaerobic conditions in autotrophically grown Pseudomonas saccharophila

1973; Elsevier BV; Volume: 159; Issue: 1 Linguagem: Inglês

10.1016/0003-9861(73)90490-6

1096-0384

M. Ishaque, Alfred L. Donawa, Muhammad Aleem,

Photoreceptor and optogenetics research

Abstract The cell-free preparations from autotrophieally grown Pseudomonas saccharophila catalyzed the process of electron transport from H 2 or various other organic electron donors to either O 2 or NO 3 − with concomitant ATP generation. The respective P O ratios with H 2 and NADH were 0.63 and 0.73, the respective P NO 3 − ratios were 0.57 and 0.54. In contrast, the P O and P NO 3 − ratios with succinate were 0.18 and 0.11, respectively. ATP formation coupled to the oxidation of ascorbate, in the absence or presence of added N,N,N′,N′ -tetramethyl- p -phenylenediamine or cytochrome c , could not be detected. Various uncouplers inhibited phosphorylation with either O 2 or NO 3 − as terminal electron acceptors without affecting the oxidation of H 2 or other substrates. The NADH oxidation at the expense of O 2 or NO 3 − reduction as well as the associated phosphorylation were inhibited by rotenone and amytal. The aerobic and anaerobic H 2 oxidation and coupled ATP synthesis, on the other hand, was unaffected by the flavoprotein inhibitors as well as by the NADH trapping system. The NADH, H 2 , and succinate-linked electron transport to O 2 or NO 3 − and the associated phosphorylations were sensitive, however, to antimycin A or 2- n -nonyl-4-hydroxyquino-line- N -oxide, and cyanide or azide. The data indicated that although the phosphorylation sites 1 and II were associated with NADH oxidation by O 2 or NO 3 − , the energy conservation coupled to H 2 oxidation under aerobic or anaerobic conditions appeared to involve site II only.