title: Crystal structure of guaiacol and phenol bound to a heme peroxidase.
abstract: Guaiacol is a universal substrate for all peroxidases, and its use in a simple colorimetric assay has wide applications. However, its exact binding location has never been defined. Here we report the crystal structures of guaiacol bound to cytochrome c peroxidase (CcP). A related structure with phenol bound is also presented. The CcP-guaiacol and CcP-phenol crystal structures show that both guaiacol and phenol bind at sites distinct from the cytochrome c binding site and from the δ-heme edge, which is known to be the binding site for other substrates. Although neither guaiacol nor phenol is seen bound at the δ-heme edge in the crystal structures, inhibition data and mutagenesis strongly suggest that the catalytic binding site for aromatic compounds is the δ-heme edge in CcP. The functional implications of these observations are discussed in terms of our existing understanding of substrate binding in peroxidases [Gumiero A et al. (2010) Arch Biochem Biophys 500, 13-20].
authors.affiliation: Department of Chemistry, University of Leicester, Leicester, UK.
authors.forename: Emma J
authors.initials: EJ
authors.lastname: Murphy
authors.forename: Clive L
authors.initials: CL
authors.lastname: Metcalfe
authors.forename: Chukwudi
authors.initials: C
authors.lastname: Nnamchi
authors.forename: Peter C E
authors.initials: PC
authors.lastname: Moody
authors.forename: Emma L
authors.initials: EL
authors.lastname: Raven
mesh_terms: D001665:Binding Sites; D018360:Crystallography, X-Ray; D003578:Cytochrome-c Peroxidase / Q000737:chemistry* / Q000378:metabolism; D006139:Guaiacol / Q000378:metabolism*; D016297:Mutagenesis, Site-Directed; D019800:Phenol / Q000378:metabolism*
chemical_list: D019800:Phenol; D006139:Guaiacol; D003578:Cytochrome-c Peroxidase