Energy conversion in autotrophically grown Pseudomonas saccharophila.

Abstract

1 Studies were undertaken to investigate the energy coupling mechanism in autotrophically grown Pseudomonas saccharophila. The cell-free extracts from Pseudomonas saccharophila contained flavoproteins and cytochromes of b, c, a, and o type. 2 Added NADH was oxidized rapidly but it was not coupled to phosphorylation. The oxidation of generated NADH, was mediated, however, by the flavoprotein and cytochrome systems and yielded P/O ratios ranging from 0.86 to 1.23. 3 The oxidation of hydrogen was mediated by the cytochrome systems but NAD+ was not involved; H2 oxidation yielded P/O ratios between 0.45 and 0.73. 4 Succinate oxidation resulted in a P/O ratio of 0.15 while ascorbate oxidation was not coupled to phosphorylation. 5 The phosphorylation coupled to the oxidation of hydrogen, NADH or succinate was completely uncoupled by various uncouplers of oxidative phosphorylation and phosphate esterification associated with the oxidation of NADH was quite sensitive to the flavoprotein inhibitors such as rotenone, amytal, and atabrine. These inhibitors had no effect, however, on the phosphorylation coupled to hydrogen or succinate oxidation. 6 The ATP formation associated with the oxidation of hydrogen, NADH or succinate was inhibited by antimycin A or 2-n-nonyl-4-hydroxyquinoline-N-oxide as well as by cyanide or azide.