Intramolecular electron transfer in sulfite-oxidizing enzymes: elucidating the role of a conserved active site arginine.

ABSTRACT: All reported sulfite-oxidizing enzymes have a conserved arginine in their active site which hydrogen bonds to the equatorial oxygen ligand on the Mo atom. Previous studies on the pathogenic R160Q mutant of human sulfite oxidase (HSO) have shown that Mo-heme intramolecular electron transfer (IET) is dramatically slowed when positive charge is lost at this position. To improve our understanding of the function that this conserved positively charged residue plays in IET, we have studied the equivalent uncharged substitutions R55Q and R55M as well as the positively charged substitution R55K in bacterial sulfite dehydrogenase (SDH). The heme and molybdenum cofactor (Moco) subunits are tightly associated in SDH, which makes it an ideal system for improving our understanding of residue function i

SUBMITTER: Emesh S 

PROVIDER: S-EPMC2765491 | biostudies-literature | 2009 Mar

REPOSITORIES: biostudies-literature