Rhus vernicifera stellacyanin

Thiobacillus ferrooxidans function. 6, 651 Rhus vernicifera stellacyanin structure, 6,651 Riboflavin 5 -phosphate zinc complexes, 5,958 Ribonucleotide reductases cobalt, 6,642 iron, 6,634... 

The same model has been used to fit the data obtained for the reactions of azurin, Az(Cu(I)) and Rhus vernicifera stellacyanin, St(Cu(I)), with Cr(III)(phen)3 and Ru(II)(bpy)3 oxidants. Values of the rate constants kt and stability constants K and K2 of the 1 1 and 2 1 complexes that have been extracted from the analyses are given in Table 2. 

Co(II) has been the most useful metal probe for the study of BCE The Co(II) derivatives of Ps. aeruginosa azurin (Moratal Mascarell et al., 1993a Piccioli et al., 1995 Salgado et al., 1995), Rhus vernicifera stellacyanin (Fernandez et al., 1997 Vila, 1994 Vila and Fernandez, 1996), Ac. cyclo-clastes pseudoazurin (Fernandez et al., 2001), Thi. ferrooxidans rusticyanin (Donaire et al., 2001), Thi. versutus amicyanin (Salgado et al., 1999), several mutants of azurin (Piccioli et al., 1995 Salgado et al., 1996, 1998a Vila et al., 1997), and the M99Q mutant of amicyanin (Diederix et al., 2000) have been prepared, and their H NMR spectra have been characterized. 

Self-exchange rate constants have been determined for P. aeruginosa and A. dinitrificans azurin (63) and T. versutus amicyanin (68) by NMR line broadening, and for Rhus vernicifera stellacyanin by EPR... 

Rhus vernicifera stellacyanin is a blue copper glycoprotein that reacts rapidly with many inorganic redox agents (37, 117, 169). In the chromous reduction of the protein (37), ET is believed to involve binding of Cr(II) to y-COi of Asp-49 and e-NH3 of Lys-50 the Cr(II) to Cu(II) ET would then take place over a Cr-Cu distance of —11 A. Since a model of the structure of stellacyanin indicates that there are no other negative residues near Asp-49, it can be concluded that the labeling is primarily due to favorable ET reactivity at the 49-50 site (190). 

Rhus vernicifera stellacyanin has been labeled with asRu + at both exposed histidines, His-32 and 100 (38, 39). A pulse radiolysis study was carried out, and both the Ru(III) and Cu(II) sites were reduced by formate radicals on the order of 1 x 10 A/ s", in 55 and 45% proportions. A slower reduction of Cu(II) also was found this was attributed to Ru(II) to Cu(II) ET, with a rate constant of 0.05 s. Since a crystal structure of stellacyanin is not available, the ET distances were estimated from a computer model to be —16.1 A (39). The relatively low ET rate is in line with the slow ET reactions observed for azurin and plastocyanin. 

Nickel - The H NMR spectra of [(5,10,15,20-Ph4-21,23-O2-porphyrin)NiPhBr] show substantial low frequency shifts. An analysis of the H NMR spectra of reduced Ni-octaethylprphin complexes has allowed the conclusion that the first and third excess electrons are localized on orbitals on the porphyrin ligand. NMR data have also been reported for [NiLX2], L = (86), (87), and Ni substituted Rhus vernicifera stellacyanin." ... 

Another interesting blue protein is stellacyanin (FW = 20 000) from the Japanese lacquer tree Rhus vernicifera, in which, with respect to the other cupredoxins, glutamine replaces the methionine ligand.64 Stellacyanin also bears an overall positive charge (p/=9.9). It, therefore, gives a reversible Cu(II)/Cu(I) response at a glassy carbon electrode in aqueous solution (pH 7.6).61 The formal electrode potential of the Cu(II)/Cu(I) reduction (E01 = + 0.18 V vs. NHE) is the lowest among cupredoxins. 

Visible MCD spectra of plastocyanin, azurin, Rhus vernicifera laccase, ascorbate oxidase and ceruloplasmin are similar on a per copper basis, but show differences from those of stellacyanin and fungal laccase. This is of interest in view of the absence of methionine from the coordination sphere of copper in stellacyanin, and the very high redox potential of fungal laccase.925... 

Cu-O-(Gln) bond of 2.21 A in the 1.6 A structure and 2.36 A in the newly refined 1.2 A structure. This bond lengthens to 2.5 A in the structure of the reduced protein at 1.45 A resolution (Figure 6d). The spectroscopic properties of cucumber stellacyanin are nearly identical to that of the protein from Rhus vernicifera ... 

Group 11. Paramagnetic (1H, 15N) NMR spectra were used to study a Cu -IDA (=iminodiacetic acid) complex localised on a protein surface. H and 13C NMR spectra were reported for copper(II) bis-benzimidazole complexes.1225 Variable temperature H NMR spectra of copper complexes of p-octafluorinated triarylcorroles reveal a thermally-accessible paramagnetic excited state, i.e. a Cu11 corrole 7i-cation radical.1226 Copper(II) forms of stellacyanin from Rhus vernicifera were characterised by H NMR.1227... 

The type 1 copper center of the phytocyanins differs from that of the other small blue proteins in that the methionine ligand is replaced by a glutamine [24]. The redox potential of stellacyanin from Rhus vernicifera is 184 mV [68]. 

Stellacyanins are different from other phytocyanins and cupredoxins by the nature of the axial ligand coordinated to the copper the axial ligand is a conserved glutamine instead of methionine. They also exhibit lower reduction potentials (180-280 mV vs. NHE) than other cupredoxins, and undergo redox reactions with small inorganic complexes or at electrodes at unusually fast rates.The stellacyanin subfamily includes stellacyanins from lacquer tree Rhus Vernicifera and cucumber Cucumis sativus, mavicyanin from green zucchini, and umecyanin from horseradish root. 

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