Journal of Protein Chemistry

, Volume 2, Issue 5, pp 363–370 | Cite as

Dependence of reactivity and cooperativity in normal human erythrocyte glucose-6-phosphate dehydrogenase on ionic strength, pH, and temperature

  • Suara A. Adediran
Article

Abstract

The steady-state kinetics of the binding reaction of NADP+ to normal human erythrocyte glucose-6-phosphate dehydrogenase were studied as a function of pH, ionic strength, and temperature. The interaction coefficient obtained according to the Hill equation increases with increase in pH, ionic strength, and temperature. The observed variation of cooperative interaction is interpreted in terms of an increase in the percentage of the dimer as these environmental parameters increase. Activation energy decreases with increase in pH, the activation energy at the lowest pH being almost halved at the most alkaline pH. This behavior is explained in terms of a differential reactivity between the dimeric and tetrameric forms of the enzyme. The observation of cooperative and more reactive dimer is postulated to be a regulatory mechanism by the cell for shifting the equilibrium from one quaternary structure to the other depending on the need for NADPH.

Key words

reactivity cooperativity human erythrocyte glucose-6-phosphate dehydrogenase 

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Afolayan, A., and Luzzatto, L. (1971).Biochemistry 10, 415–419.Google Scholar
  2. Anstall, H. B., and Trujillo, J. M. (1967).Am. J. Clin. Pathol. 47, 296–302.Google Scholar
  3. Babalola, A. O. G., Beetlestone, J. G., and Luzzatto, L. (1976).J. Biol. Chem. 251, 2993–3002.Google Scholar
  4. Bonsignore, A., Lorenzoni, I., Cancedda, R., and De Flora, A. (1970).Biochem. Biophys. Res. Commun. 39, 142–148.Google Scholar
  5. Cancedda, R., Ogunmola, G. B., and Luzzatto, L. (1973).Eur. J. Biochem. 34, 199–204.Google Scholar
  6. Chung, A. E., and Langdon, R. G. (1963).J. Biol. Chem. 00, 2317–2324.Google Scholar
  7. Cohen, P., and Rosemeyer, M. A. (1969a).Eur. J. Biochem. 8, 1–7.Google Scholar
  8. Cohen, P., and Rosemeyer, M. A. (1969b).Eur. J. Biochem. 8, 8–15.Google Scholar
  9. De Flora, A., Morelli, A., Benatti, U., and Giuliano, F. (1975).Arch. Biochem. Biophys. 169, 362–363.Google Scholar
  10. Grove, T. H., Ishaque, A., and Levy, H. R. (1976).Arch. Biophys. 177, 307–316.Google Scholar
  11. Hill, A. V. (1910).J. Physiol. 40, iv-vii.Google Scholar
  12. Huang, C. Y., and Graves, D. J. (1970).Biochemistry 9, 660–671.Google Scholar
  13. Krikman, H. N. (1962).J. Biol. Chem. 237, 2364–2370.Google Scholar
  14. Klapper, M. H. (1971).Biochem. Biophys. Acta 229, 557–566.Google Scholar
  15. Luzzatto, L. (1967).Biochim. Biophys. Acta 146, 18–25.Google Scholar
  16. Luzzatto, L., and Testa, U. (1978).Curr. Top. Hematol. 1, 1–70.Google Scholar
  17. Millar, D. B. S. (1962).J. Biol. Chem. 237, 2135–2139.Google Scholar
  18. Yoshida, A., and Hoagland, V. D., Jr. (1970).Biochem. Biophys. Res. Commun. 40, 1167–1172.Google Scholar
  19. Yoshida, A., and Lin, M. (1973).Blood 41, 877–891.Google Scholar

Copyright information

© Plenum Publishing Corporation 1983

Authors and Affiliations

  • Suara A. Adediran
    • 1
  1. 1.Department of ChemistryUniversity of IbadanIbadanNigeria

Personalised recommendations