Pyrococcus furiosus glyceraldehyde 3‐phosphate oxidoreductase has comparable W^6+/5+ and W^5+/4+ reduction potentials and unusual [4Fe‐4S] EPR properties

Abstract

Pyrococcus furiosus glyceraldehyde 3-phosphate oxidoreductase has been characterized using EPR-monitored redox titrations. Two different W signals were found. W 5 1 is an intermediate species in the catalytic cycle, with the midpoint potentials E m (W 6 a5 ) = 3 3507 mV and E m (W 5 a4 ) = 3 3491 mV. W 5 2 represents an inactivated species with E m (W 6 a5 ) = 3 3329 mV. The cubane cluster exhibits both S = 3/2 and S = 1/2 signals with the same midpoint potential : E m ([4Fe-4S] 2 a1 ) = 3 3335 mV. The S = 1/2 EPR signal is unusual with all g values below 2.0. The titration results combined with catalytic voltammetry data are consistent with electron transfer from glyceraldehyde 3-phosphate first to the tungsten center, then to the cubane cluster and finally to the ferredoxin.z 1999 Federation of European Biochemical Societies.

Spectroscopic and Electrochemical Characterization of the Iron–Sulfur and Cobalamin Cofactors of TsrM, an Unusual Radical S-Adenosylmethionine Methylase

“…While the latter set of g-values do fall in the range that is typical for [4Fe− 4S] + clusters, the g-values for the spectrum in the presence of SAM are very unusual. There are only a few reported cases of a [4Fe−4S] + cluster that exhibits such an unusual g-matrix, such as glyceraldehyde 3-phosphate oxidoreductase 68 and NADHreduced glutamate synthase. 69 In both cases, these unusual spectra were observed in the presence of additional paramagnetic species.…”

From liquid to thin film: colloidal suspensions for tungsten oxide as an electrode material for Li-ion batteries

“…7), as W 6+ and W 5+ can be discriminated based on their reduction potentials. 51,66 A rst reduction peak at 2.67 V can be related to the reduction of W 6+ to W 5+ (indicated by 1 in Fig. 7), the second reduction at 2.38 V corresponds to the consecutive W 5+ to W 4+ reduction 51 (indicated by 2 in Fig.…”

Electroanalytical Determination of Tungsten and Molybdenum in Proteins

“…The xanthine oxidase concentration was determined using ⑀ 450 ϭ 72 mM Ϫ1 cm Ϫ1 (12). Pyrococcus furiosus glyceraldehyde-3-phosphate oxidoreductase was purified as described (13). The glyceraldehyde-3-phosphate oxidoreductase concentration was determined using the bicinchoninic acid protein assay and the molar mass of 80 kDa based on the amino acid sequence (14).…”

“…P. furiosus (DSM 3638) cells were grown and cell free extract was obtained as previously described (13). Cell-free extract was loaded using an FPLC system (Pharmacia) on a 300 ml DEAE-Sepharose Fast Flow column (Pharmacia) equilibrated with 20 mM Tris-HCl buffer, pH 8.0.…”