Effect of enzymic assay conditions on sulfite reduction catalysed by desulfoviridin from Desulfovibrio gigas

Variations in the Spectrum of Desulfoviridin From Desulfovibrio gigas

“…It was noted, however, that for several preparations of desulfoviridin the position of the p-peak was at longer wavelengths than 580 nm and the ratio of the extinction coefficients of the p-and a-peaks, Ep-peak : E~-peak' was highest for those preparations with a p-peak at 585-586 nm. This was consistent with published results; the ratio AE(588-700) : AE(627-700)* for the preparation of Jones and Skyring (1974) was O' 53 whereas it was 0·42 for other preparations (Lee and Peck 1971;Jones and Skyring 1975). Irrespective of the position of the p-peak, none of the preparations fluoresced in 365-nm u.v.…”

“…Generally, the spectrum of desulfoviridin does not significantly alter on treatment with sodium dithionite, Na 2 S 2 0 4 (Postgate 1956;Ishimoto and Koyama 1957;Lee and Peck 1971;Murphy and Siegel 1973;Lee et al 1973;Jones and Skyring 1975). However, Jones and Skyring (1974) showed that with a desulfoviridin preparation having a p-peak at 588 nm a reaction occurred with Na 2 S 2 0 4 in which the extinction at 588 nm decreased and the effect was reversed with K 3 Pe(CN)6' The effect of Na2 S204 on this preparation of desulfoviridin was similar to that reported for P582, the sulphite reductase of Desulfotomaculum nigrificans (Trudinger 1970).…”

“…The extractable prosthetic group of the enzyme is an isobacteriochlorin (postgate 1956;Murphy and Siegel 1973 ;Skyring 1975). Spectra of purified preparations of desulfoviridin from Desulfovibrio gigas NCIB* 9332 have major absorption peaks at 627-628 nm (oc-peak) and 408-409 nm (Soret peak); however, the absorption peak in the 580-590-nm (JJ-peak) region of the spectrum has been given as 580 nm (Lee and Peck 1971), 581 nm (Jones and Skyring 1975), 583 nm (Murphy and Siegel 1973), and 588 nm (Jones and Skyring 1974). Another instance of unexplained variability in desulfoviridin spectra is that of the differences in the preparations from D. vulgaris NCIB 8303 by Postgate (1956) and by Lee et al (1973); absorption maxima of the former preparation were at 630, 585, 411, and 390 nm whilst for the latter they were at 628, 580, 408, and 390 nm.…”

Microbiological fractionation of stable sulfur isotopes: A review and critique

“…In dissimilatory reduction, the picture is not as clear since trithionate and thiosulfate have been shown to accumulate during sulfite reduction by cell-free extracts and purified enzymes from Desulfovibrio and Desulfotomaculum spp. (Suh and Akagi, 1969;Kobayashi et al, 1969Kobayashi et al, , 1972Kobayashi et al, , 1974Lee and Peck, 1971;Akagi and Adams, 1973;Jones and Skyring, 1975;Drake and Akagi, 1976). Based on this and other observations it has been suggested that dissimilatory sulfite reduction may proceed through three stages involving three separate enzymes and the recycling of sulfite (see Fig.…”

A Post-Genomic View of the Ecophysiology, Catabolism and Biotechnological Relevance of Sulphate-Reducing Prokaryotes

“…This has led to a long controversy over whether SRP reduce sulphite directly to sulphide, or via a stepwise process involving thiosulphate and trithionate reductases, in a so-called trithionate pathway (Akagi, 1995). This putative trithionate pathway has been disputed because the DsrAB product composition is strongly dependent on the reaction conditions, with the production of trithionate and thiosulphate, relative to sulphide, being increased in the presence of unphysiologically high sulphite concentrations and limited electron donor (Chambers & Trudinger, 1975;Drake & Akagi, 1977;Jones & Skyring, 1975). Furthermore, no consistent evidence was ever reported for a trithionate reductase in SRP, and thiosulphate reductases are absent in many of these organisms .…”