THIOSULFATE OXIDATION AND ELECTRON TRANSPORT IN THIOBACILLUS NOVELLUS
THIOSULFATE OXIDATION AND ELECTRON TRANSPORT IN THIOBACILLUS NOVELLUS
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DOI：
10.1128/jb.90.1.95-101.1965
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发表时间：
1965-01-01
影响因子：
3.2
通讯作者：
ALEEM, MIH
中科院分区：
文献类型：
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作者：
ALEEM, MIH
从T.适合于生长的novellus自养。自养生长细胞的酶系统通过c型和a型细胞色素将电子从硫代硫酸盐转移到分子氧;该反应由硫代硫酸盐氧化酶和硫代硫酸盐细胞色素-c还原酶共同催化。这两种酶的水平显着降低在异养生长的生物体。从自养生长的T. Novellus催化甲酸盐氧化并用甲酸盐酶促还原细胞色素-C。在异养条件下，甲酸氧化和细胞色素c还原活性被取消。硫代硫酸盐活化酶S2 O3 - 2-细胞色素-C还原酶，以及硫代硫酸盐氧化酶，主要定位于可溶性无细胞馏分，和前者的酶纯化超过200倍，通过硫酸铵分级和磷酸钙凝胶吸附程序。纯化的酶的最佳活性发生在pH 8.0，在1.67 × 10-1 M S_2O_3 - 2和2.5 × 10-4 M细胞色素-c的存在下。硫代硫酸盐氧化酶在pH 7.5和硫代硫酸盐浓度为1.33 x 10-3至3.33 x 10-2 M，加入浓度为5 x 10-4 M的细胞色素c的情况下最佳运行。这两种酶显着敏感氰化物和在较小程度上，一些金属结合剂。虽然10-3 M浓度的对羟基苯甲酸汞对S_2O_3 -2细胞色素-C还原酶没有影响，但它对S_2O_3 - 2氧化酶有50%的抑制作用，在10-3 M还原型谷胱甘肽存在下，这种抑制作用完全逆转。一氧化碳也抑制S_2O_3 - 2氧化酶，这种抑制作用可被光完全逆转。
A cell-free soluble enzyme system capable of oxidizing thiosulfate was obtained from T. novellus adapted to grow autotrophically. The enzyme systems of autotrophically grown cells brought about the transfer of electrons from thiosulfate to molecular oxygen via cytochromes of the c-and a-types; the reactions were catalyzed jointly by thiosulfate oxidase and thiosulfate cytochrome-c reductase. The levels of both of these enzymes were markedly reduced in the heterotrophically grown organism. Cell-free extracts from the autotrophically grown T. novellus catalyzed formate oxidation and enzymatically reduced cytochrome-c with formate. Both formate oxidation and cytochrome-c reduction activities were abolished under heterotrophic conditions. The thiosulfate-activating enzyme S2O3 -2-cytochrome-c reductase, as well as thiosulfate oxidase, was localized chiefly in the soluble cell-free fractions, and the former enzyme was purified more than 200-fold by ammonium sulfate fractionation and calcium phosphate gel adsorption procedures. Optimal activity of the purified enzyme occurred at pH 8.0 in the presence of 1.67 x 10-1 M S2O3 -2 and 2.5 x 10-4 M cytochrome-c. The thiosulfate oxidase operated optimally at pH 7.5 and thiosulfate concentrations of 1.33 x 10-3 to 3.33 x 10-2 M in the presence of added cytochrome-c at a concentration of 5 x 10-4 M. Both enzymes were markedly sensitive to cyanide and to a lesser extent to some metal-binding agents. Although a 10-3 M concentration of p-hydroxymercuibenzoate had no effect on S2O3-2 cytochrome-c reductase, it caused a 50% inhibition of S2O3 -2 oxidase, which was completely reversed in the presence of 10-3 M reduced glutathione. Carbon monoxide also inhibited S2O3 -2 oxidase; the inhibition was completely reversed by light.