Influence of the enzyme dissimilatory sulfite reductase on stable isotope fractionation during sulfate reduction
Influence of the enzyme dissimilatory sulfite reductase on stable isotope fractionation during sulfate reduction
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酶异化亚硫酸盐还原酶对硫酸盐还原过程中稳定同位素分馏的影响
DOI：
10.1016/j.gca.2008.01.006
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发表时间：
2008
影响因子：
5
通讯作者：
W. Stichler
中科院分区：
文献类型：
--
作者：
Muna Mangalo;F. Einsiedl;R. Meckenstock;W. Stichler
硫酸盐的稳定同位素常被用作在宏观尺度上评估细菌硫酸盐还原的工具。然而，硫和氧在酶水平上稳定同位素分馏的机理还不完全清楚。在富含18O的水的间歇实验中，我们考察了不同亚硝酸盐浓度对脱硫弧菌分离硫同位素的影响。随着亚硝酸盐浓度的增加，硫同位素富集系数从−11.2±1.8‰到−22.5±3.2‰。此外，当供应富含18O的水时，剩余硫酸盐中的δ18O值从大约50-120‰增加。由于与环境水的18O-交换不是发生在硫酸盐中，而是发生在硫酸盐还原途径的中间产物(如SO32-)中，我们认为亚硝酸盐影响代谢中间产物亚硫酸盐在硫酸盐还原过程中的稳态浓度和再氧化成硫酸盐的程度。鉴于亚硝酸盐可以抑制异化亚硫酸盐还原酶的产生，我们的结果表明，异化亚硫酸盐还原酶的活性调节了细菌硫酸盐还原过程中硫和氧的动态同位素分馏。我们的新结果还表明，细菌硫酸盐还原过程中的同位素分馏强烈依赖于细胞内部的酶调节，而不是单个酶的物理化学特征。
The stable isotopes of sulfate are often used as a tool to assess bacterial sulfate reduction on the macro scale. However, the mechanisms of stable isotope fractionation of sulfur and oxygen at the enzymatic level are not yet fully understood. In batch experiments with water enriched in18O we investigated the effect of different nitrite concentrations on sulfur isotope fractionation by Desulfovibrio desulfuricans. With increasing nitrite concentrations, we found sulfur isotope enrichment factors ranging from −11.2±1.8‰ to −22.5±3.2‰. Furthermore, the δ18O values in the remaining sulfate increased from approximately 50–120‰ when18O-enriched water was supplied. Since18O-exchange with ambient water does not take place in sulfate, but rather in intermediates of the sulfate reduction pathway (e.g. SO32-), we suggest that nitrite affects the steady-state concentration and the extent of reoxidation of the metabolic intermediate sulfite to sulfate during sulfate reduction. Given that nitrite is known to inhibit the production of the enzyme dissimilatory sulfite reductase, our results suggest that the activity of the dissimilatory sulfite reductase regulates the kinetic isotope fractionation of sulfur and oxygen during bacterial sulfate reduction. Our novel results also imply that isotope fractionation during bacterial sulfate reduction strongly depends on the cell internal enzymatic regulation rather than on the physico-chemical features of the individual enzymes.
DOI：
--
发表时间：
1991-09
期刊：
--
影响因子：
--
作者：
P. Cook
通讯作者：
P. Cook