High resolution 31P nuclear magnetic resonance studies of metabolism in aerobic Escherichia coli cells

G. Navon, S. Ogawa, R. G. Shulman, T. Yamane

Research output: Contribution to journalArticlepeer-review

Abstract

31P nuclear magnetic resonance spectra at 145.7 MHz were obtained of concentrated suspensions of E. coli cells. The position of the Pi resonance was used to determine the pH, and in most experiments it was possible to distinguish the intracellular (pHin) and extracellular (pHex) values. During respiration pH in approached 7.55, while pHex varied from 6.0 to 8.0. With succinate as a carbon source and in a N2 environment, pHin=pHex. Upon addition of glucose, pHin > pHex. In the presence of an ATPase (adenosinetriphosphatase; ATP phosphohydrolase; EC 3.6.1.3) inhibitor dicyclohexylcarbodiimide, pHin remained equal to pHex even in the presence of glucose. In other experiments, oxygenation brought pHin above pHex even in the presence of dicyclohexylcarbodiimide. These experiments are consistent with Mitchell's hypothesis that, first, ΔpH can be created by the reversal of the ATPase reaction and, second, that protons are pumped outward during respiration. In addition to Pi, about 10 more resonances were resolved, several of which were assigned to different phosphate metabolites.

Original languageEnglish
Pages (from-to)888-891
Number of pages4
JournalProceedings of the National Academy of Sciences of the United States of America
Volume74
Issue number3
DOIs
StatePublished - 1977
Externally publishedYes

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