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首页> 外文期刊>Archives of microbiology >Membrane-associated redox activities in Thermotoga neapolitana
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Membrane-associated redox activities in Thermotoga neapolitana

机译：热那亚菌的膜相关氧化还原活性

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Elemental sulfur reduction by the hyperthermophilic bacterium Thermotoga neapolitana provides an alternative to hydrogen evolution during fermentation. Electrons are transferred from reduced cofactors (ferredoxin and NADH) to sulfur by a series of unknown steps. One enzyme that may be involved is an NADH:methyl viologen oxidoreductase (NMOR), an activity that in other fermenting organisms is associated with NADH:ferredoxin oxidoreductase. We found that 83% of NMOR activity was contained in the pellet fraction of cell extracts subjected to ultracentrifugation. This pellet fraction, presumably containing cell membranes, was required for electron transfer to NAD(+) from ferredoxin-dependent pyruvate oxidation. However, the NMOR activity in this fraction used neither Thermotoga nor clostridial ferredoxins as substrates. NMOR activity was also detected in aerobically prepared vesicles. By comparison with ATPase activities, NMOR was found primarily on the cytoplasmic face of these vesicles. During these studies, an extracytoplasmic hydrogenase activity was discovered. In contrast to the soluble hydrogenase, this hydrogenase activity was completely inhibited when intact cells were treated with cupric chloride and was present on the extracytoplasmic face of vesicles. In contrast to a soluble hydrogenase reported in Thermotoga maritima, this activity was air-stable and was inhibited by low concentrations of nitrite. [References: 33]
机译：嗜热嗜热菌嗜热菌（Thermotoga neapolitana）对元素硫的还原提供了发酵过程中析氢的替代方法。电子通过一系列未知步骤从还原的辅因子（铁氧还蛋白和NADH）转移到硫。可能涉及的一种酶是NADH：甲基紫精氧化还原酶（NMOR），该活性在其他发酵生物中与NADH：铁氧还蛋白氧化还原酶有关。我们发现，经过超速离心的细胞提取物的沉淀级分中包含83％的NMOR活性。从铁氧还蛋白依赖性丙酮酸氧化电子转移至NAD（+）时需要此沉淀部分（大概包含细胞膜）。但是，该级分的NMOR活性均未使用Thermotoga或梭菌铁氧还蛋白作为底物。在需氧制备的囊泡中也检测到NMOR活性。与ATPase活性比较，NMOR主要在这些囊泡的细胞质表面上发现。在这些研究中，发现了胞质外氢化酶活性。与可溶性氢化酶相反，当完整细胞用氯化铜处理时，这种氢化酶活性被完全抑制，并存在于囊泡的胞浆外表面。与马氏热球菌中报道的可溶性氢化酶相反，该活性是空气稳定的，并被低浓度的亚硝酸盐抑制。 [参考：33]

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