Metabolism of deoxyinosine by human erythrocyte ghosts

Abstract

Deoxyinosine was metabolized by human erythrocyte ghosts. Kinetic studies revealed an accumulation of hypoxanthine, a decrease in deoxypentose, and an initial uptake of inorganic phosphate followed by its eventual release. Intermediates of the pathway identified were triose phosphate (glyceraldehyde 3-phosphate and dihydroxyacetone phosphate), phosphoglycerates, acetaldehyde, lactate, and xylulose 5-phosphate. No glucose 6-phosphate or fructose 6-phosphate was found in contrast to the extensive synthesis previously obtained with inosine. Although most of the phosphorylated intermediates were accounted for, the ester pool was only 40 % of the substrate utilized at the kinetic maximum. Deoxyinosine is metabolized differently than inosine in that acetaldehyde is an intermediate and the phosphate ester pool is much more labile. The accumulation of ketopentose phosphates (xylulose 5-phosphate and ribulose 5-phosphate) in ghosts from deoxynucleosides demonstrates that a pathway exists in erythrocytes for the conversion of the deoxypentose of the nucleoside to ketopentose.