Multiconformation continuum electrostatics analysis of the effects of a buried Asp introduced near heme a in Rhodobacter sphaeroides cytochrome c oxidase.

ABSTRACT: Cytochrome c oxidase (CcO) reduces O(2) to water via a series of proton-coupled electron transfers, generating a transmembrane electrochemical gradient. Coupling electron and proton transfer requires changing the pK(a) values of buried residues at each stage in the reaction cycle. Heme a is a key cofactor in the CcO electron transfer chain. Mutation of Ser44 to Asp has been reported [Mills, D. A., et al. (2008) Biochemistry 47, 11499-11509], changing the hydrogen bond acceptor from His102, the heme a axial ligand in Rhodobactor sphaeroides CcO. This adds an acidic residue to the CcO interior. The electrochemical behavior of heme a in wild-type and S44D CcO is compared using the continuum electrostatics program MCCE. The introduced, deeply buried Asp remains ionized at physiological pH only

SUBMITTER: Zhang J 

PROVIDER: S-EPMC3800205 | biostudies-literature | 2010 Sep

REPOSITORIES: biostudies-literature