A CALORIMETRIC STUDY ON THE INTERACTION OF ZINC ION WITH HUMAN GROWTH HORMONE

Document Type : Regular Paper

Authors

1 Department of Chemistry, Science and Research Branch, Islamic Azad University, Tehran, I. R. of Iran

2 Institute of Biochemistry and Biophysics, University of Tehran, Tehran, I. R. of Iran

3 Department of Chemistry, Imam Khomeini International University, Qazvin, I. R. of Iran

Abstract

A thermodynamic study on the interaction between zinc ion (Zn2+) and human growth hormone
(hGH) was studied at two temperatures of 27C and 37C in aqueous solution using an isothermal titration
calorimetry. It was found that there is a set of three identical and non-interacting binding sites for Zn2+ ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are 1.54 mM and 17.6 kJ mol-1 at 27C and 1.93 mM and 7.1 kJ mol-1 at 37C, respectively. To reproduce the binding parameters of metal ionhormone interaction over the whole range of Zn2+ concentrations a solvation theory was applied. The binding parameters deduced from the solvation model were attributed to the structural change of hGH and its biological activity due to the metal ion interaction

Keywords

Iranian Journal of Science
Volume 33, Issue 4 - Serial Number 4
November and December 2009
Pages 317-327

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