RED CELL TRIOKINASE DEFICIENCY - ANOTHER BIOCHEMICAL CHARACTERISTIC OF THE FETAL ERYTHROCYTE

Abstract

The erythrocytes of normal adults have the capacity to incorporate and metabolize dihydroxyacetone (DHA). This substrate has been found to be useful for the maintenance of 2, 3-diphosphoglycerate (DPG) in stored red cells. The metabolism of DHA by cord blood erythrocytes was examined in an attempt to find a substrate for DPG synthesis that bypassed the early steps in red cell glycolysis. When the cells from adults and infants were incubated in the presence of DHA (10 mM), pyruvate (10 mM), and inorganic phosphate (10 mM), the DPG level increased by 2.34 μmoles/ml RBC's in the adult samples but only increased by 0.1 μmoles/ ml in the cells of infants during a period of 2 hours. DHA consumption averaged 3.76 μmoles/ml RBC's/hr in the cells from adults but was only 1.16 μmoles/ml RBC's/hr in the erythrocytes of the newborn. Assays of triokinase, the enzyme responsible for the phosphorylation of DHA, were performed in the hemolysates from newborn and adult erythrocytes. Triokinase activity averaged 4.56 ± 0.69 units/100 ml RBC's in adults and was only 2.97 ± 0.54 units in the cells from newborns (p <.01). Relative triokinase deficiency appears to be another biochemical characteristic of the red cells of the newborn infant.