We are studying the metabolism and enzymes of 2,3-diphosphoglycerate (2,3-DPG) in the human red blood cell. We are interested in knowing how the level of 2,3-DPG is regulated in red cells in vivo and the factors responsible for its decline in stored red cells. It is known that 2,3-DPG levels in red cells change in response to pH and hypoxia but the controlling mechanisms have not been satisfactorily defined. We shall examine carefully the properties of purified 2,3-DPG phosphatase to see if they fully account for the observed stability of 2,3-DPG in red cells. We are also doing 31P-nuclear magnetic resonance studies of whole red cells in an attempt to calculate the normal level of ionized magnesium. We are carrying out a steady-state kinetic study of phosphoglycerate mutase, which catalyzes the reaction glycerate-3-P reversibly yields glycerate-2-P in the presence of 2,3-DPG. Due to the lack of a satisfactory assay no adequate study has been done until now. BIBLIOGRAPHIC REFERENCES: Rates of phosphorylation and dephosphorylation of phosphoglycerate mutase and bisphosphoglycerate synthase. Rose, Z. B. and Dube, S. J. Biol. Chem. 251:4817-4822, 1976. The purification and kinetic properties of bisphosphoglycerate synthase from horse red blood cells. Rose, Z. B. and Dube, S. Arch. Biochem. Biophys. 177:284-292, 1976.