Purification and properties of 3-phosphoglyceric acid mutase from caprine erythrocytes

Abstract

Relatively simple procedures are described for preparing partially purified phosphoglycerate mutase from erythrocytes of the goat. The kinetic properties of this enzyme are described and compared to those of the same enzyme from human erythrocytes. The K m for 3-phosphoglyceric acid is 6 × 10 −4 m. The enzyme has an absolute requirement for 2,3-diphosphoglyceric acid with a K m of 5 × 10 −6 m. 2,3-Diphosphoglyceric acid phosphatase activity co-purified with the phosphoglyceric acid mutase. This activity, thought to be an activity of the same enzyme, is greatly stimulated by inorganic pyrophosphate. Its K m for pyrophosphate is 1 × 10 −2 m and for 2,3-diphosphoglyceric acid in the phosphatase assay is 1.2 × 10 −4 m. No kinetic differences were found between the enzymes of human and caprine origins. The concentration of 2,3-diphosphoglyceric acid in caprine erythrocytes was measured enzymically and found to be 0.03 μmoles per ml cells, approximately 1% of the amount present in the erythrocytes of man. That amount of 2,3-diphosphoglycerate is nevertheless 5-fold above the enzyme's K m value for this cofactor. A second 2,3-diphosphoglyceric acid phosphatase, stimulated by bisulfite, was detected in caprine red cells but its activity was far less than in human erythrocytes.