RESUMO
Recombinant human gamma-interferon is dimeric in solution at pH 7-4 as revealed by analytical gel-filtration. It was shown by circular dichroism that decreasing pH to 5.0 does not affect the secondary and tertiary structures of gamma-interferon macromolecule. It was established that heat denaturation process of gamma-interferon obeys the two-state transition model and can be described as the first-order reversible reaction. Temperature dependence of the denaturation-renaturation rate constants was shown to be consistent with the Arrhenius law. The equilibrium value of the denaturation temperature was found. Effective enthalpy of denaturation was determined both by thermodynamic and kinetic approaches. The data obtained showed that in the pH range 7-4 the dimeric IFN-gamma structure may be considered as a single cooperative thermodynamic domain. Thus, it may be concluded that gamma-interferon dimerization is necessary for the existence of the corresponding tertiary structure of the macromolecule.
Assuntos
Interferon gama/química , Varredura Diferencial de Calorimetria , Cromatografia em Gel , Dicroísmo Circular , Cinética , Conformação Proteica , Desnaturação Proteica , Proteínas Recombinantes/química , TermodinâmicaRESUMO
The work presents the results of experimental study of gamma interferon obtained by gene engineering techniques on the basis of Escherichia coli producer strains. The study has revealed that gamma interferon, whose molecular weight is 15 KD, due to intracellular proteolytic degradation shows the absence of some amino acids at the C-end of protein and is electrophoretically homogeneous, while its antiviral, antiproliferative and immunomodulating effects are less pronounced than those of gamma interferon with a molecular weight of 18 KD.