SOME THERMODYNAMIC AND KINETIC ASPECTS OF METABOLIC PHOSPHORYLATION

Abstract

From a survey of the evidence which bears on the relationship between oxidation and phosphorylation, mainly from the viewpoints of thermodynamics and kinetics, the authors conclude: (1) It is doubtful whether the present evidence justifies the assumption of a P:O ratio greater than 2 in the oxidation of pyruvate. (2) According to our present knowledge it is difficult to understand on kinetic grounds how a P:O ratio even as low as 2 can be achieved at an appreciable rate of reaction. (3) It has been shown that catalytic effects of intermediates on oxidation might be due to their assisting in the diffusional transport of hydrogen. In this connection, the question of the spatial distribution of enzymes is again of importance. Such an action of intermediates could be combined with that of phosphate transport.