Glycolysis in Young and Mature Normal Human Erythrocytes

Abstract

CONSIDERABLE data exist concerning the decline of metabolic activity which occurs during the normal ageing of human erythrocytes. In particular, several of the glycolytic enzymes are present in higher concentration in younger cells (that is, reticulocytes). This is true of phosphohexoisomerase^1,2, triosephosphate dehydrogenase³, aldolase², glucose-6-phosphate dehydrogenase and 6-phosphogluconic dehydrogenase^1,4. However, in the assay methods used the maximum activity of these enzymes is measured at their optimum pH in dilute hæmolysates containing added excess of substrate, coenzyme and activator; these are conditions which do not obtain in intact erythrocytes. Indeed, the results of Chapman et al.⁵ demonstrate that glucose consumption in normal intact erythrocytes proceeds at a rate less than that calculable from the concentrations of Embden–Meyerhof pathway enzymes that are present. It does not follow, therefore, that the presence of higher concentrations of glycolytic enzymes, as in reticulocytes, produces an increased rate of glycolysis. However, Bernstein² showed that glucose consumption and lactate production in intact erythrocytes were, in fact, increased in proportion to the reticulocyte concentration of the samples.