10912
Biochemistry 1993, 32, 10912-10922
Resonance Ranian Study of the Interactions between Cytochrome c Variants and Cytochrome c Oxidase? Peter Hildebrandt,'J Franck Vanhecke,t Gerhard Buse,l Tewfik Soulimane,s and A. Grant Maukll Max-Planck-Institut f i r Strahlenchemie, Stijtstrasse 34-36, 0-45470 Miilheim, Germany, Institut f i r Biochemie, Rheinisch- Westfilische Technische Hochschule Aachen Klinikum, Pauwelsstrasse 30, 0-52074 Aachen, Germany, and Department of Biochemistry, University of British Columbia, Vancouver,British Columbia, Canada V6T 1 Z3 Received April 22, 1993; Revised Manuscript Received July 19, 1993"
ABSTRACT:
The structural changes in oxidized yeast iso- 1-cytochrome c and fully oxidized bovine cytochrome
c oxidase that are induced upon complex formation have been analyzed by resonance Raman spectroscopy. The main spectral changes could be ascribed to cytochrome c, which in the case of the wild-type protein are essentially the same as previously observed in the complex of horse heart cytochrome c and bovine cytochrome c ox: :ase [Hildebrandt et al. (1990) Biochemistry 29, 1661-16681. These spectral changes are attributed to the formation of the conformational state I1 (-45%) which exhibits an open heme pocket structure. The structural changes are assumed to be induced by the electrostatic interactions between the negctively charged binding domain on cytochrome c oxidase and the positively charged lysine residues on the front surface of cytochrome c. Substituting one of these lysine residues (Le., Lys-72) by an alanine significantly lowers the state I1 content (
