Enzyme Regulatory Mechanisms at the Level of Lactate-oxidoreductase in Erythrocytes and Ascites Tumour Cells

Abstract

IN recent years several attempts have been made at a complete analysis of metabolic pathways. In comparing complex systems, be they intact cells or homogenates, with isolated enzymes, both similarities and differences^1–3 have been found. So far no single pathway has been completely elucidated with respect to its kinetics. For this reason we turned to the erythrocyte, as representing both structurally and metabolically one of the simplest biological systems. One line of research which is to be reported here was concerned with the regulation of glycolysis on the level of lactate oxido-reductase. These studies were extended to ascites tumour cells. In view of the generally high activity of the lactate oxido-reductase (LDH) it may be assumed that the lactate/pyruvate system is at equilibrium within the cell¹. Recently, however, deviations from the expected lactate/pyruvate ratios have been observed in brain homogenates³. We explored this question in a more detailed manner by studying the effect of pH on the formation of pyruvate and lactate.