Article: Role of magnesium in the (Ca2+ + Mg2+)-stimulated membrane ATPase of human red blood cells

(Ca2+ + Mg2+)-stimulated ATPase of human red cell membranes as a function of ATP concentration was measured at fixed Ca2+ concentration and at two different but constant Mg2+ concentrations. Under the assumption that free ATP rather than Mg-ATP is the substrate, a value for Km (for ATP) of 1-2 micron is found which is in good agreement with the value obtained in the phosphorylation reaction by A.F. Rega and P.J. Garrahan (1975. J. Membrane Biol. 22:313). Mg2+ increases both the maximal rate and the affinity for ATP, whereas Ca2+ increases the maximal rate without affecting Km for ATP. As a by-product of these experiments, it was shown that after thorough removal of intracellular proteins the adenylate kinase reaction at approximately 1 mM substrate concentration is several times faster than maximal rate of (Ca2+ + Mg2+)ATPase in red cell membranes.

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References

1.

Feldhau P, Frohlich T, Goody R, Isakov M, Schirmer R . Synthetic inhibitors of adenylate kinases in the assays for ATPases and phosphokinases. Eur J Biochem. 1975; 57(1):197-204. DOI: 10.1111/j.1432-1033.1975.tb02291.x. View

2.

Markland F, Wadkins C . Adenosine triphosphate-adenosine 5'-monophosphate phosphotransferase of bovine liver mitochondria. II. General kinetic and structural properties. J Biol Chem. 1966; 241(18):4136-45. View

3.

Wolf H . Studies on a Ca 2+ -dependent ATPase of human erythrocyte membranes. Effects of Ca 2+ and H + . Biochim Biophys Acta. 1972; 266(2):361-75. DOI: 10.1016/0005-2736(72)90094-6. View

4.

Rega A, Garrahan P . Calcium ion-dependent phosphorylation of human erythrocyte membranes. J Membr Biol. 1975; 22(3-4):313-27. DOI: 10.1007/BF01868177. View

5.

Sen A, POST R . STOICHIOMETRY AND LOCALIZATION OF ADENOSINE TRIPHOSPHATE-DEPENDENT SODIUM AND POTASSIUM TRANSPORT IN THE ERYTHROCYTE. J Biol Chem. 1964; 239:345-52. View

6.

DUNHAM E, Glynn I . Adenosinetriphosphatase activity and the active movements of alkali metal ions. J Physiol. 1961; 156:274-93. PMC: 1359885. DOI: 10.1113/jphysiol.1961.sp006675. View

7.

LOWRY O, ROSEBROUGH N, FARR A, RANDALL R . Protein measurement with the Folin phenol reagent. J Biol Chem. 1951; 193(1):265-75. View

8.

Wins P, Schoffeniels E . Studies on red-cell ghost ATPase systems: properties of a (Mg2+ + Ca2+)-dependent ATPase. Biochim Biophys Acta. 1966; 120(3):341-50. DOI: 10.1016/0926-6585(66)90301-3. View

9.

Knauf P, Proverbio F, Hoffman J . Electrophoretic separation of different phophosproteins associated with Ca-ATPase and Na, K-ATPase in human red cell ghosts. J Gen Physiol. 1974; 63(3):324-36. PMC: 2203554. DOI: 10.1085/jgp.63.3.324. View

10.

SCHATZMANN H, VINCENZI F . Calcium movements across the membrane of human red cells. J Physiol. 1969; 201(2):369-95. PMC: 1351614. DOI: 10.1113/jphysiol.1969.sp008761. View

11.

BERENBLUM I, CHAIN E . Studies on the colorimetric determination of phosphate. Biochem J. 1938; 32(2):286-94. PMC: 1264025. DOI: 10.1042/bj0320286. View

Role of Magnesium in the (Ca2+ + Mg2+)-stimulated Membrane ATPase of Human Red Blood Cells