Myoglobin electron transfer

An alternative application of flash photolysis to study myoglobin electron transfer kinetics has been employed by Hofifinan and co-workers 156). In this approach, the photoactive zinc-substituted derivative of Mb is mixed with an equivalent amoimt of ferricytochrome bs to form an electrostatically stabilized binary complex. Upon transient irradiation, the strongly reducing Zn-Mb intermediate is formed, and the kinetics of ferricytochrome reduction within the preformed complex can be monitored spectrophotometrically. The resulting kinetics represents a mixed-order process consistent with electron transfer both within the electrostatically stabilized complex and between the dissociated components of the complex. 

IV. MYOGLOBIN ELECTRON TRANSFER AND LIGAND-BINDING REACTIONS... 

Biosensors based on direct electron transfer of myoglobin... 

I. Taniguchi, K. Watanabe, M. Tominaga, and F.M. Hawkridge, Direct electron transfer of horse heart myoglobin at an indium oxide electrode. J. Electroanal. Chem. 333, 331-338 (1992). 

M. Tominaga, T. Kumagai, S. Takita, and I. Taniguchi, Effect of surface hydrophilicity of an indium oxide electrode on direct electron transfer of myoglobins. Chem. Lett. 10, 1771-1774 (1993). 

A.E.F. Nassar, W.S. Willis, and J.F. Rusling, Electron transfer from electrodes to myoglobin facilitated in surfactant films and blocked by adsorbed biomacromolecules. Anal. Chem. 67, 2386-2392 (1995). 

A.E.F. Nassar, Z. Zhang, N.F. Hu, J.F. Rusling, and T. Kumosinski, Protein-coupled electron transfer from electrodes to myoglobin in ordered biomembrane-like films. J. Phys. Chem. B 101, 2224-2231 (1997). 

Fig. 8. A view into the interior of a ruthenium modified myoglobin where the amino acids in the vicinity of Trp-14 are shown. The dots correspond to the statistieal density Pn i,(r) of (discretized) tunneling path vertices (rj in Eq. 26) from 500,000 tunneling paths [19], The (r) is clustered in a cylindrical zone centered on the average path, shown as the light line appearing in the center and emerging toward the viewer. The computation modeled paths of electron transfer in Ru(His-12) myoglobin studied experimentally by Gray and coworkers [88]...

Electron transfer to the protein metal center is monitored spectroscopically. In the case of a heme (FeP), a fast increase in absorbance due to direct reduction of Fe(III)P by Ru(bpy)f is followed by a slower increase in absorbance due to reduction of Fe(III)P by the Ru(II) on the protein surface. Control flash experiments with unmodified proteins show only the fast initial increase in absorbance due to Fe(III)P reduction by Ru(bpy)3. Such control experiments demonstrate for horse heart cytochrome c [21], azurin [28], and sperm whale myoglobin [14] that slow reduction of the heme by the EDTA radical produced in the scavenging step does not occur in competition with intramolecular ET. However, for Candida krusei cytochrome c, the control experiment shows evidence for slow EDTA radical reduction of the heme after initial fast reduetion by Ru(bpy)i+ [19]. 

The reversible first-order reaction (1.47) can be converted into an irreversible A X process by scavenging X rapidly and preventing its return to A. Thus the intramolecular reversible electron transfer in modified myoglobin (Sec. 5.9)... 

Direct electron transfer has also been achieved with many metalloproteins such as cytochrome C, horseradish peroxidase, microperoxidase (MP-11), myoglobin, hemoglobin, catalase, azurin, and so on, immobilized on different CNT-modified electrodes [45, 61, 144—153]. 

B. Mutagenesis of the Proximal Heme Binding Pocket Electron Transfer Reactions of Myoglobin... 

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