Developmental changes of mouse red cell pyruvate kinase

The increase in red cell 2,3-diphosphoglycerate (2,3-DPG) concentration during mouse postnatal development is highly correlated with the decrease in red cell pyruvate kinase (PK) activity. Immunoneutralization curves for newborn and adult red cell PK are parallel, which suggests that the higher PK activity in newborn mouse red cells is due primarily to a greater quantity of PK protein. Mouse newborn and adult red cell PK also differ in mobility on cellulose acetate electrophoresis (pH 7.5). This is true for two strains of mice (C57BL/6 and IS/Cam) whose adult red cell PK electrophoretic patterns differ (single vs. double bands, respectively). Trypsinization does not alter the electrophoretic mobilities of C57BL/6 newborn and adult red cell PK, but it does convert the IS/Cam adult PK to a single band of greater mobility than the single band of C57BL/6 adult PK. These data are consistent with the hypothesis that mice have structurally different forms of PK for newborn and adult red cells, analogous to the fetal gamma- and adult beta-globins of humans.