Peroxidase activity of cytochrome c in its compact state depends on dynamics of the heme region

Publication date: Available online 13 September 2018Source: Biochimica et Biophysica Acta (BBA) - Proteins and ProteomicsAuthor(s): Nataša Tomášková, Rastislav Varhač, Veronika Lysáková, Andrej Musatov, Erik SedlákAbstractCytochrome c (cyt c) is a small globular hemoprotein with the main function as an electron carrier in mitochondrial respiratory chain. Cyt c possesses also peroxidase-like activity in the native state despite its six-coordinated heme iron. In this work, we studied the effect of increasing urea concentration in the range from 0 M to 6 M at pH 7 (pH value of the bulk solvent) and pH 5 (pH value close to negatively charged membrane) on peroxidase-like activity of cyt c. We show that peroxidase-like activity, measured by guaiacol oxidation and the ferrous oxidation in xylenol orange methods, correlates with the accessibility of the heme iron, which was assessed from the association rate constant of cyanide binding to cyt c. Cyt c peroxidase-like activity linearly increases in the pre-denaturational urea concentrations (0–4 M) at both studied pHs without an apparent formation of pentacoordinated state of the heme iron. Our results suggest that dynamics equilibrium among the denaturant-induced non-native coordination states of cyt c, very likely due to reversible unfolding of the least stable foldons, is pre-requisite for enhanced peroxidase-like activity of cyt c in its compact state. Dynamics replacement of the native sixth coordination bond ...
Source: Biochimica et Biophysica Acta (BBA) Proteins and Proteomics - Category: Biochemistry Source Type: research