Myoglobin in surfactant films

Bayachou, M., L. Elkbir, and P.J. Farmer (2000). Catalytic two-electron reductions of N2O and by myoglobin in surfactant films. Inorg. Chem. 39, 289-293. 

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). 

D. Mimica, J.H. Zagal, and F. Bedioui, Electroreduction of nitrite by hemin, myoglobin and haemoglobin in surfactant films. J. Electroanal. Chem. 497, 106-113 (2001). 

Y.J. Hu, N.F. Hu, and Y.H. Zeng, Electrochemistry and electrocatalysis with myoglobin in biomembrane-like surfactant-polymer 2C 2N+PA composite films. Talanta 50, 1183-1195 (2000). 

L.W. Wang and N.F Hu, Electrochemistry and electrocatalysis with myoglobin in biomembrane-like DHP-PDDA polyelectrolyte-surfactant complex films. J. Colloid Interface Sci. 236, 166—172 (2001). 

L.W. Wang and N.F. Hu, Electrochemistry and electrocatalysis with myoglobin in biomembrane-like DHP-PDDA polyelectrolyte-surfactant complex films. J. Colloid Interface Sci. 236,166-172 (2001). Z.H. Dai, X.X. Xu, and H.X. Ju, Direct electrochemistry and electrocatalysis of myoglobin immobilized on a hexagonal mesoporous silica matrix. Anal. Biochem. 332, 23-31 (2004). 

Surfactant films accommodate proteins in a more hydrophobic environment. These films seem to stabilize many proteins, and often enhance their electron-transfer and catalytic properties. Surfactant films have been effective for proteins ranging from myoglobin to large membrane-bound systems such as the photosynthetic reaction center [19-21]. 

In 1993, we reported [19] reversible electron transfer between electrodes and the iron heme protein myoglobin imbedded in cast multi-lameUar liquid crystal films of didodecyldimethylammonium bromide (DDAB). Heretofore, reversible electron transfer from electrodes to myoglobin in solution had been accomplished only for highly purified myoglobin solutions on specially cleaned indium tin oxide electrodes [20,21]. If enhanced electron transfer for proteins in surfactant or lipid films were to prove general, it might help solve longstanding problems in protein electrochemistry. 

Table 1 Formal potentials and electron transfer rate constants for thin (0.5-1 nm) myoglobin-surfactant films on PG electrodes in pH 7 buffer containing no protein...

Recently, collaboration between the author, A-E. Nassar, and N. Nakashima resulted in the preparation of stable films of calf thymus double-stranded DNA and proteins on electrodes [55]. Direct electron transfer was achieved for myoglobin or hemoglobin in DNA films on pyrolytic graphite (PG) electrodes. As with the surfactant films, enhanced electron transfer rates were achieved compared to bare PG electrodes with proteins in solution. DNA films also extracted proteins from solution. Mb appears to diffuse through pure DNA films such faster than Hb. Conformational changes in both DNA and protein upon binding are likely within these films. DNA-protein films may find applications in electrochemical and spectroscopic studies of DNA-protein and DNA-enzyme-sub-strate interactions, and as biosensors for proteins. 

Mb-surfactant films were used for the catalytic reduction of organohalide pollutants. Moreover, preliminary results in our laboratory show that oxidative catalysis should also be possible. Thus, films containing myoglobin, and the more difficult to obtain cyt P450cani> provide models to study chemical process which may activate pollutants for carcinogenesis in the human liver. Cyt P450 enzymes thought to activate pollutants are membrane bound, so the lipid films provide simplified but realistic environments for chemical studies of this enzyme catalysis. 

---