Mutations Pro----Ala-35 and Tyr----Phe-75 of Rhodobacter capsulatus ferrocytochrome c2 affect protein backbone dynamics: measurements of individual amide proton exchange rate constants by 1H-15N HMQC spectroscopy.

摘要: Comparisons of hydrogen-deuterium solvent exchange rate constants for the NH protons wild-type Pro----Ala-35 (P35A) and Tyr----Phe-75 (Y75F) Rhodobacter capsulatus ferrocytochromes c2 were made by 1H-15N heteronuclear multiple-quantum correlation spectroscopy. Exchange increased residues 45-46, 54, 57-58, 60-61, 82-87, 98, 100 with Y75F 16-18, 20, 34, 37, 43, 58 P35A. The increases in are consistent changes unfolding equilibria protein dynamics. In observable helix spanning Pro-79-Asp-89, namely Phe-82-Leu-87, increase to a similar degree, suggesting that this is single cooperative unit compatible local model. As oxidation-reduction potential 59 mV lower than cytochrome (367 mV), dynamic mutant, compared wild-type, proposed be important determinants potential. Several differences between common P35A, mutation which does not affect potential, implying all observed functionally important.