Adenosine phosphosulfates

FIGURE 6.3 Quantification on the first half of an isolated peak. The spectrum is from the [2Fe-2S] cluster in the enzyme adenosine phosphosulfate reductase from Desulfovibrio vulgaris (Verhagen et al. 1993). The inset shows the asymmetrical low-field -feature the vertical line at the peak position indicates the rightmost integration limit for quantification on half... 

FIGURE 13.6 Whole bacterial-cell EPR. A frozen concentrated suspension of cells from the sulfate-reducing bacterium Desulfovibrio vulgaris gives an EPR spectrum with only a [2Fe-2S]1+ signal and a flavin radical signal, both from adenosine phosphosulfate reductase. 

Verhagen, M.F.J.M., Kooter, I.M., Wolbert, R.B.G., and Hagen, W.R. 1993. On the iron-sulfur cluster of adenosine phosphosulfate reductase from Desulfovibrio vulgaris (Hildenborough). European Journal of Biochemistry 221 831-837. 

The biochemical pathway of both assimilatory and dissimilatory sulfate reduction is illustrated in Figure 1. The details of the dissimilatory reduction pathway are useful for understanding the origin of bacterial stable isotopic fractionations. The overall pathways require the transfer of eight electrons, and proceed through a number of intermediate steps. The reduction of sulfate requires activation by ATP (adenosine triphosphate) to form adenosine phosphosulfate (APS). The enzyme ATP sulfurylase catalyzes this reaction. In dissimilatory reduction, the sulfate moiety of APS is reduced to sulfite (SO3 ) by the enzyme APS reductase, whereas in assimilatory reduction APS is further phosphorylated to phospho-adenosine phosphosulfate (PAPS) before reduction to the oxidation state of sulfite and sulfide. Although the reduction reactions occur in the cell s cytoplasm (i.e., the sulfate enters the cell), the electron transport chain for dissimilatory sulfate reduction occurs in proteins that are peiiplasmic (within the bacterial cell wall). The enzyme hydrogenase... 

Asssimilatory sulfate reduction via adenosine phosphosulfate (and phosphoadenylyl sulfate in prokaryotes and fungi), thiosulfate, and sulfide... 

The first bacterial DPCK to be cloned and characterized was the E. coli CoaE protein coaE gene product, previously yacE), which was identified by a basic local alignment search tool (BLAST) using the N-terminal sequence of the wild-type enzyme purified from C. ammoniagenes The enzyme is a 22.6-kDa monomer in solution and exhibits apparent values of 140 pmol 1 and 740 pmol for ATP and dephospho-CoA, respectively. It displays poor activity with adenosine, AMP, and adenosine phosphosulfate (APS) as alternate phosphoryl acceptors, which all shows less than 8% activity compared with the natural substrate. Studies on the bifiinctional PPAT/ DPCK protein show that the normally reversible PPAT activity becomes irreversible when it is coupled to DPCK, most probably because the latter activity demonstrates a low K- for dephospho-CoA of 5.2 L5 pmol 1 (its for ATP was found to be 192 14 pmol 1 ). ° Similar values were determined in an independent study. ... 

Sulfate reduction reduction of the sulfote ion S04 " to the sulfide ion S, in which the hexavalent, positive sulfur of the sulfate is converted to the divalent, negative form. S.r. must be preceded by Sulfate activation (see). The substrate of enzymatic S.r. is therefore either adenosine phosphosulfate (APS) or phosphoadenosinephosphosulfate (PAPS). The enzy-mology of S.r. has been studied in particular in enzyme preparations from baker s yeast (Saccharomy-ces cerevisiae) and the anaerobic bacterium Desulfo-vibrio desulfuricans. The former organism performs assimilatory S.r. (see Sulfate assimilation), Ae latter dissimilatory S.r. (see Sulfate respiration). 

Adenosine phosphosulfate — AMP -p enzyme-bound-flavin-sulfate... 

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