Electronic Structures of Active Sites in Copper Proteins and Their Contributions to Reactivity

Direct electron transfer between copper-containing proteins and electrodes

“…Azurin is a small blue copper protein (9-14 kDa) and is one of the simplest redox proteins that contains a mononu- clear copper of the T1 type (Solomon et al, 1992;Jeuken et al, 2000). As was mentioned above the T1 copper sites exhibit several distinguishing spectroscopic characteristics, which include an intense blue colour associated with a strong absorption band in the visible region of 600 nm.…”

“…2). The redox potentials of azurins from different sources were estimated and found to be in the range from 270 to 320 versus NHE (Solomon et al, 1992;Zhang et al, 2002;Pinho et al, 2004).…”

“…Oxidation-reduction reactions involve either outersphere electron transfer, as in the blue copper proteins, the Cu A site of cytochrome c oxidase and nitrous oxide reductase, or inner-sphere electron transfer in the binding, activation, and reduction of dioxygen, superoxide, nitrite, and nitrous oxide. The copper sites in the redox proteins have historically been divided into three classes based on their spectroscopic features, which reflect the geometric and electronic structure of the active site: type 1 (T1) or blue copper, type 2 (T2) or normal copper, and type 3 (T3) or coupled binuclear copper centres (Malkin and Malmström, 1970;Reinhammar, 1984;Solomon et al, 1992;Kaim and Rall, 1996) ( Table 1). Over the last 20 years, this list has expanded to include the trinuclear copper clusters (comprised of one type 2 and one type 3 centre) (Table 1) (Allendorf et al, 1985;Messerschmidt et al, 1992), the mixed-valent binuclear Cu A site (Agostinelli et al, 1995;Iwata et al, 1995;Tsukihara et al, 1995), the Cu B -heme A centre of cytochrome c oxidase (Kaim and Rall, 1996;Malmström, 1990), and the binuclear Cu Z centre of nitrous oxide reductase (Farrar et al, 1991).…”

Synthesis and Characterization of Heteropolynuclear Redox Active Materials[FerCuCl]4YY′; Y = Y′ = O, Y = Y′ = Cat and Y = O, Y′ = Cat, Fer = N,N-dimethylaminomethylferrocene and Cat = 3,4,5,6-tetrachlorocatecholato Ligand

“…spectra. The catecholato ligand bridges two copper(II) centers on one of the cubane faces, similar to the catechol/copper(II) intermediate for the catalytic cycle of tyrosinase in oxidation of phenol to o-quinone [28]. Voltammograms of the Fe 2+ /Fe 3+ and catecholato 2) /benzoquinone redox couples are overlapped in [FerCuCl] 4 YY¢ over the range (+0.40 V to )0.80 V).…”

Surface modifications for enhanced enzyme immobilization and improved electron transfer of PQQ-dependent glucose dehydrogenase anodes

“…Subsequently, the performance of biofuel cells or bio-sensors is restricted by, among other factors, the rate of interfacial electron transfer between the enzyme and the surface of the electrode [4,5]. Some of the enzymes capable of DET include multi-copper oxidases [6][7][8][9][10][11][12] and pyrroloquinoline quinone (PQQ) containing enzymes (i.e. quinoproteins and quinohemoproteins) [13,14], which do not require external mediators or diffusion of coenzymes and can interact electronically directly with the electrode support.…”