A Microcalorimetry Study of the Binding of Nickel Ion by Human Growth Hormone

A binding study of nickel ions by a new recombinant human Growth Hormone (hGH), produced as an injected drug, has been done at ۲۷˚C in NaCl solution (۵۰ mM) using an isothermal titration calorimetry. There is a set of three identical and non-interacting binding sites for nickel ions. The intrinsic dissociation equilibrium constant and the molar enthalpy of binding are ۴۰ μM and -۱۶.۵ kJ/mol, respectively. Thermodynamic parameters of nickel ion binding are compared to the other metal ions. The molar entropy of binding is ۲۹.۳ J K-۱ mol-۱ for Ni۲+, less than Cu۲+ and more than other metal ions, means that the disorder of the protein structure due to the binding of nickel ions is more than to the other ion metals, except Cu۲+. It is expected that nickel ions can prevent from the aggregation of the protein.

کلیدواژه ها:

Human growth hormone ، Nickel ion ، Metal binding ، Titration calorimetry