title: Direct electrochemistry and Raman spectroscopy of sol-gel-encapsulated myoglobin.
abstract: The direct electrochemistry of myoglobin (Mb) has been observed at a glassy carbon (GC) electrode coated with silica sol-gel-encapsulated Mb film. A well-behaved cyclic voltammogram is observed with a midpoint potential (E(1/2)) of -0.25 V vs Ag/AgCl in a pH 7.0 phosphate buffer. This potential, which is pH-dependent, is 70-90 mV more negative than the formal potential values obtained by using the spectroeletrochemical titration method at the same pH. Square wave voltametry (SWV) also shows a peak potential of -0.25 V for the reduction of Mb under the same experimental conditions. Both cathodic and anodic peak currents have a linear relationship with the scan rate. The midpoint potential decreases with pH, having a slope of -30 mV/pH. UV-vis and resonance Raman spectroscopic studies reveal that the sol-gel provides a bio-compatible environment where Mb retains a structure similar to its solution form, a 6-coordinated aquomet myoglobin. These results suggest that the silica sol-gel is a useful matrix for studying direct electrochemistry of other heme proteins.
authors.affiliation: Department of Chemistry, Jackson State University, 1400 J.R. Lynch Street, Jackson, Mississippi 39217, USA.
authors.forename: Anandhi
authors.initials: A
authors.lastname: Ray
authors.forename: Manliang
authors.initials: M
authors.lastname: Feng
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Tachikawa
mesh_terms: D000818:Animals; D004563:Electrochemistry / Q000379:methods*; D004566:Electrodes; D006418:Heme / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D009211:Myoglobin / Q000737:chemistry*; D044367:Phase Transition; D010710:Phosphates / Q000737:chemistry; D013059:Spectrum Analysis, Raman / Q000379:methods*; D014466:Ultraviolet Rays
chemical_list: D009211:Myoglobin; D010710:Phosphates; D006418:Heme