The sulfane sulfur of persulfides is the actual substrate of the sulfur-oxidizing enzymes from Acidithiobacillus and Acidiphilium spp.
The sulfane sulfur of persulfides is the actual substrate of the sulfur-oxidizing enzymes from Acidithiobacillus and Acidiphilium spp.
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DOI：
10.1099/mic.0.26212-0
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发表时间：
2003-07-01
期刊：
影响因子：
2.8
通讯作者：
Sand, W
中科院分区：
文献类型：
--
作者：
Rohwerder, T;Sand, W
为了鉴定谷胱甘肽依赖性硫双加氧酶（EC 1.13.11.18）的实际底物，分析了中嗜酸氧化硫杆菌菌株DSM 504和K6、氧化亚铁硫杆菌菌株R1和嗜酸嗜酸菌DSM 700的元素硫氧化。在粗提物中发现了极高的硫双加氧酶比活性，高达460 nmol min（-1）（mg蛋白质）（-1）。所有无细胞系统仅通过谷胱甘肽过硫化物（GSSH）氧化元素硫，谷胱甘肽（GSH）和元素硫的非酶反应产物。因此，GSH在元素硫活化中起催化作用，但在酶促硫烷硫氧化过程中不被消耗。亚硫酸盐是硫双加氧酶活性的第一个产物;它进一步非酶反应为硫酸盐、硫代硫酸盐或谷胱甘肽S-磺酸盐（GSSO（3）（-））。游离硫化物不被硫双加氧酶氧化。过硫化物作为硫供体不能被其他含硫化合物（硫代硫酸盐、连多硫酸盐、双有机基聚硫烷或单芳基硫代磺酸盐）取代。双加氧酶对H2S的氧化需要GSSG，即GSH的二硫化物，其在酶促氧化之前与硫化物非酶促反应以产生GSSH。在此基础上，建立了嗜酸硫杆菌和嗜酸菌中元素硫和硫化物氧化的生物化学模型。本文提出
To identify the actual substrate of the glutathione-dependent sulfur dioxygenase (EC 1.13.11.18) elemental sulfur oxidation of the meso-acidophilic Acidithiobacillus thiooxidans strains DSM 504 and K6, Acidithiobacillus ferrooxidans strain R1 and Acidiphilium acidophilum DSM 700 was analysed. Extraordinarily high specific sulfur dioxygenase activities up to 460 nmol min(-1) (mg protein)(-1) were found in crude extracts. All cell-free systems oxidized elemental sulfur only via glutathione persulfide (GSSH), a non-enzymic reaction product from glutathione (GSH) and elemental sulfur. Thus, GSH plays a catalytic role in elemental sulfur activation, but is not consumed during enzymic sulfane sulfur oxidation. Sulfite is the first product of sulfur dioxygenase activity; it further reacted non-enzymically to sulfate, thiosulfate or glutathione S-sulfonate (GSSO(3)(-)). Free sulfide was not oxidized by the sulfur dioxygenase. Persulfide as sulfur donor could not be replaced by other sulfane-sulfur-containing compounds (thiosulfate, polythionates, bisorganyl-polysulfanes or monoarylthiosulfonates). The oxidation of H2S by the dioxygenase required GSSG, i.e. the disulfide of GSH, which reacted non-enzymically with sulfide to give GSSH prior to enzymic oxidation. On the basis of these results and previous findings a biochemical model for elemental sulfur and sulfide oxidation in Acidithiobacillus and Acidiphilium spp. is proposed.