par Malaisse Lagae, Francine 
;Zahner, Dagmar ;Malaisse, Willy
Référence International journal of biochemistry & cell biology, 27, 9, page (905-909)
Publication Publié, 1995
;Zahner, Dagmar ;Malaisse, Willy Référence International journal of biochemistry & cell biology, 27, 9, page (905-909)
Publication Publié, 1995
Article révisé par les pairs
| Résumé : | The present study explores the possible chanelling of pyruvate generated by either pyruvate kinase or NADP-malate dehydrogenase to lactate dehydrogenase in cross-linked and permeabilized erythrocytes. The generation of both unlabelled and 14C-labelled pyruvate and lactate was measured in rat erythrocytes, which were prepared for cross-linking with dimethyl suberimidate and permeabilization by digitonin and then exposed to unlabelled or 14C-labelled malate and/or phospho-enol-pyruvate. Rat erythrocytes were found to display NADP-malate dehydrogenase activity. Under conditions in which the generation rates of pyruvate from either phospho-enolpyruvate (15 μM) or malate (0.5 mM) were not vastly different from one another, a greater fraction of the 2-keto acid was converted to lactate when produced from phospho-enol-[1-14C] pyruvate rather than [U-14C]malate. This difference was most obvious when the availability of exogenous NADH was close to or somewhat below that theoretically required to ensure full conversion of endogenously formed pyruvate to lactate. These findings are compatible with the view that pyruvate generated at the pyruvate kinase level is converted to lactate more efficiently than pyruvate produced in the reaction catalysed by NADP-malate dehydrogenase. |
