Role of the aromatic ring of Tyr43 in tetraheme cytochrome c(3) from Desulfovibrio vulgaris Miyazaki F.

ABSTRACT: Tyrosine 43 is positioned parallel to the fifth heme axial ligand, His34, of heme 1 in the tetraheme cytochrome c(3). The replacement of tyrosine with leucine increased the redox potential of heme 1 by 44 and 35 mV at the first and last reduction steps, respectively; its effects on the other hemes are small. In contrast, the Y43F mutation hardly changed the potentials. It shows that the aromatic ring at this position contributes to lowering the redox potential of heme 1 locally, although this cannot be the major contribution to the extremely low redox potentials of cytochrome c(3). Furthermore, temperature-dependent line-width broadening in partially reduced samples established that the aromatic ring at position 43 participates in the control of the kinetics of intramolecular electron tran

SUBMITTER: Ozawa K 

PROVIDER: S-EPMC1303614 | biostudies-literature | 2003 Nov

REPOSITORIES: biostudies-literature