title: Electrochemistry of cytochrome P450 BM3 in sodium dodecyl sulfate films.
abstract: Direct electrochemistry of the cytochrome P450 BM3 heme domain (BM3) was achieved by confining the protein within sodium dodecyl sulfate (SDS) films on the surface of basal-plane graphite (BPG) electrodes. Cyclic voltammetry revealed the heme FeIII/II redox couple at -330 mV (vs Ag/AgCl, pH 7.4). Up to 10 V/s, the peak current was linear with the scan rate, allowing us to treat the system as surface-confined within this regime. The standard heterogeneous rate constant determined at 10 V/s was estimated to be 10 s-1. Voltammograms obtained for the BM3-SDS-BPG system in the presence of dioxygen exhibited catalytic waves at the onset of FeIII reduction. The altered heme reduction potential of the BM3-SDS-graphite system indicates that SDS is likely bound in the enzyme active-site region. Compared to other P450-surfactant systems, we find redox potentials and electron-transfer rates that differ by approximately 100 mV and >10-fold, respectively, indicating that the nature of the surfactant environment has a significant effect on the observed heme redox properties.
authors.affiliation: Department of Chemistry, Occidental College, Los Angeles, California 90041, USA.
authors.forename: Andrew K
authors.initials: AK
authors.lastname: Udit
authors.forename: Michael G
authors.initials: MG
authors.lastname: Hill
authors.forename: Harry B
authors.initials: HB
authors.lastname: Gray
mesh_terms: D001665:Binding Sites; D015374:Biosensing Techniques; D003577:Cytochrome P-450 Enzyme System / Q000737:chemistry*; D004563:Electrochemistry; D004572:Electrolysis; D006108:Graphite / Q000737:chemistry; D006418:Heme / Q000737:chemistry*; D008567:Membranes, Artificial; D010084:Oxidation-Reduction; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry*; D013329:Structure-Activity Relationship; D013499:Surface Properties
chemical_list: D008567:Membranes, Artificial; D012967:Sodium Dodecyl Sulfate; D006418:Heme; D006108:Graphite; D003577:Cytochrome P-450 Enzyme System