[17] Thiosulfate and trithionate reductases

Akagi, J. M.; Drake, Harold L.; Kim, Jae-Ho; Gevertz, D.

doi:10.1016/0076-6879(94)43019-5

Cited by 6 publications

(14 citation statements)

References 16 publications

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“…Whereas the reaction mechanism for the thiosulfate-forming enzyme has been determined (Akagi et al, 1994), the mechanics underpinning trithionate and thiosulfate reduction by DsrAB (Parey et al, 2010) or otherwise are underdetermined. For example, the importance of the thionate loop could be resolved through in vitro studies of fractionation factors associated with trithionate and thiosulfate formation and reduction.…”

Section: Discussionmentioning

confidence: 99%

“…These reactions require enzymes (trithionate reductase and thiosulfate reductase), which have been partially characterized in some sulfate-reducing bacteria (Ishimoto et al, 1955;Haschke & Campbell, 1971;Hatchikian, 1975;Drake & Akagi, 1977;Akagi et al, 1994). These reactions require enzymes (trithionate reductase and thiosulfate reductase), which have been partially characterized in some sulfate-reducing bacteria (Ishimoto et al, 1955;Haschke & Campbell, 1971;Hatchikian, 1975;Drake & Akagi, 1977;Akagi et al, 1994).…”

Section: The Trithionate Pathwaymentioning

confidence: 99%

“…First, sulfite can be partially reduced and react to form trithionate, which may -at least in some organisms -be subsequently reduced to thiosulfate and finally to sulfide. For trithionate, at least two reduction enzymes have been reported from Desulfovibrio (Akagi et al, 1994). In each case, site-specific oxidation states should be considered in the production and consumption of these species.…”

Section: A Revised Model For the Sulfate Reduction Networkmentioning

confidence: 99%

“…Another option is that sulfite can be reduced to form thiosulfate directly, which is then partially reduced to sulfide. The first enzyme, referred to as thiosulfate-forming enzyme (TF) (Drake & Akagi, 1977;Akagi et al, 1994), catalyzes the reaction of trithionate with a sulfite molecule, forming thiosulfate and two molecules of sulfite (Fig. For example, the reductions in trithionate and ⁄ or thiosulfate result in stoichiometric productions of intracellular sulfite from their sulfonyl moieties, while the reduced moieties are further reduced to sulfide (Table 1, Fig.…”

Section: A Revised Model For the Sulfate Reduction Networkmentioning

confidence: 99%

“…4). Akagi, 1985;Akagi et al, 1994), does not rely on sulfite but splits trithionate, forming sulfite and (via a two-electron transfer) thiosulfate. The first enzyme, referred to as thiosulfate-forming enzyme (TF) (Drake & Akagi, 1977;Akagi et al, 1994), catalyzes the reaction of trithionate with a sulfite molecule, forming thiosulfate and two molecules of sulfite (Fig.…”

Section: A Revised Model For the Sulfate Reduction Networkmentioning

confidence: 99%

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Revisiting the dissimilatory sulfate reduction pathway

2011

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Sulfur isotopes in the geological record integrate a combination of biological and diagenetic influences, but a key control on the ratio of sulfur isotopes in sedimentary materials is the magnitude of isotope fractionation imparted during dissimilatory sulfate reduction. This fractionation is controlled by the flux of sulfur through the network of chemical reactions involved in sulfate reduction and by the isotope effect associated with each of these chemical reactions. Despite its importance, the network of reactions constituting sulfate reduction is not fully understood, with two principle networks underpinning most isotope models. In this study, we build on biochemical data and recently solved crystal structures of enzymes to propose a revised network topology for the flow of sulfur through the sulfate reduction metabolism. This network is highly branched and under certain conditions produces results consistent with the observations that motivated previous sulfate reduction models. Our revised network suggests that there are two main paths to sulfide production: one that involves the production of thionate intermediates, and one that does not. We suggest that a key factor in determining sulfur isotope fractionation associated with sulfate reduction is the ratio of the rate at which electrons are supplied to subunits of Dsr vs. the rate of sulfite delivery to the active site of Dsr. This reaction network may help geochemists to better understand the relationship between the physiology of sulfate reduction and the isotopic record it produces.

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Section: Discussionmentioning

confidence: 99%