Thermostability of proteins: role of metal binding and pH on the stability of the dinuclear CuA site of Thermus thermophilus.

ABSTRACT: The dinuclear copper center (TtCuA) forming the electron entry site in the subunit II of the cytochrome c oxidase in Thermus thermophilus shows high stability toward thermal as well as denaturant-induced unfolding of the protein at ambient pH. We have studied the effect of pH on the stability of the holo-protein as well as of the apo-protein by UV-visible absorption, far-UV, and visible circular dichroism spectroscopy. The results show that the holo-protein both in the native mixed-valence state as well as in the reduced state of the metal ions and the apo-protein of TtCuA were extremely stable toward unfolding by guanidine hydrochloride at ambient pH. The thermal unfolding studies at different values of pH suggested that decreasing pH had almost no effect on the thermal stability of the p

SUBMITTER: Sujak A 

PROVIDER: S-EPMC1989708 | biostudies-literature | 2007 Oct

REPOSITORIES: biostudies-literature