First direct interfacial electron transfer between a biomolecule and a solid electrode in non-aqueous media: Direct electrochemistry of microperoxidase-11 at glassy carbon in dimethyl sulfoxide solution
✍ Scribed by Patricia Ann Mabrouk
- Publisher
- Elsevier Science
- Year
- 1995
- Tongue
- English
- Weight
- 597 KB
- Volume
- 307
- Category
- Article
- ISSN
- 0003-2670
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✦ Synopsis
The direct heterogeneous electron transfer between the imidazole complex of microperoxidase-11 (im-MP-11) and naked glassy carbon electrodes in dimethyl sulfoxide (l-3.6% H,O) containing 0.1 M tetra-n-butylammonium perchlorate has been accomplished using cyclic voltammetry. Homogeneous solutions of im-MP-11 in dimethyl sulfoxide were prepared by weak complexation with 18-crown-6. Heterogeneous electron transfer between im-MP-11 and glassy carbon has been shown to be persistent and at least quasi-reversible in dimethyl sulfoxide solution. The redox potential for im-MP-11 in dimethyl sulfoxide has been found to be -274 &-5 mV vs. Ag/AgCl -significantly less negative than the potential ( -389 mV vs. Ag/AgCl) for this same complex in aqueous 75 mM phosphate buffer, pH 7.0, containing 0.1 M NaClO,. The calculated diffusion coefficient (1.8 X 10m7 cm2 s-') and the rate of electron transfer in dimethyl sulfoxide (2.7 f 0.3 X 10e4 cm s-') are approximately one order of magnitude lower than that for the same complex in 0.02 M aqueous phosphate buffer, pH 7.0.