title: Spectroscopic and functional studies of a novel quadruple myoglobin variant with increased peroxidase activity.
abstract: A quadruple variant of horse heart myoglobin (Thr39Ile/Lys45Asp/Phe46Leu/Ile107Phe) that exhibits significantly (approximately 25-fold) greater peroxidase activity than the wild-type protein has been studied to determine its midpoint reduction potential (24(2) mV vs. SHE; pH 6.0, mu = 0.1 M, 25 degrees C) and to characterize the kinetics of its reaction with hydrogen peroxide. In addition, Fourier transform infrared (FTIR) spectra of the carbonyl and azide adducts of the protein have been obtained to gain initial insight into the effects of these substitutions on the ligand binding properties of the reduced and oxidized variant. All of the results obtained in this work are consistent with a variant heme binding pocket with increased hydrophilic character.
authors.affiliation: Department of Biochemistry and Molecular Biology, University of British Columbia, Vancouver, Canada.
authors.forename: D P
authors.initials: DP
authors.lastname: Hildebrand
authors.forename: K T
authors.initials: KT
authors.lastname: Lim
authors.forename: F I
authors.initials: FI
authors.lastname: Rosell
authors.forename: M B
authors.initials: MB
authors.lastname: Twitchett
authors.forename: L
authors.initials: L
authors.lastname: Wan
authors.forename: A G
authors.initials: AG
authors.lastname: Mauk
mesh_terms: D000818:Animals; D001665:Binding Sites; D019020:Directed Molecular Evolution; D004563:Electrochemistry; D014644:Genetic Variation; D006418:Heme / Q000737:chemistry / Q000378:metabolism; D006736:Horses; D006861:Hydrogen Peroxide / Q000378:metabolism; D066298:In Vitro Techniques; D007700:Kinetics; D008024:Ligands; D008564:Membrane Potentials; D009206:Myocardium / Q000737:chemistry; D009211:Myoglobin / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D010544:Peroxidases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013053:Spectrophotometry; D017550:Spectroscopy, Fourier Transform Infrared
chemical_list: D008024:Ligands; D009211:Myoglobin; D006418:Heme; D006861:Hydrogen Peroxide; D010544:Peroxidases