Disulfide reduction and sulfhydryl uptake by Streptococcus mutans.
Disulfide reduction and sulfhydryl uptake by Streptococcus mutans.
复制标题
变形链球菌的二硫键还原和巯基摄取。
DOI：
10.1128/jb.157.1.240-246.1984
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发表时间：
1984
影响因子：
3.2
通讯作者：
Thomas,EL
中科院分区：
文献类型：
--
作者：
Thomas,EL
变形链球菌细胞与某些二硫化物化合物的孵育导致还原巯基化合物在细胞外培养基中或在培养基和细胞两者中的积累。氧化的硫辛酸和硫辛酰胺竞争还原。在高浓度下，这些化合物以与葡萄糖代谢相当的速率减少，并且巯基的所有增加都在培养基中。胱胺不与这些化合物竞争还原，但也以高速率和低表观亲和力还原，并且由胱胺产生的所有半胱胺在培养基中积累。与此相反，谷胱甘肽二硫化物（GSSG）和L-胱氨酸减少缓慢，但具有高表观亲和力，和60至80%的巯基的增加是细胞内。依赖于NADH的硫辛酸或硫辛酰胺还原酶活性存在于颗粒（壁加膜）部分，而依赖于NADPH的GSSG还原酶活性存在于可溶性（细胞质）部分。二硫化物和巯基化合物的两个运输系统进行了区分。GSSG、L-胱氨酸和还原型谷胱甘肽竞争摄取。L-半胱氨酸被一个单独的系统吸收，该系统也接受L-青霉胺和D-半胱氨酸作为底物。谷胱甘肽或L-半胱氨酸的摄取，或GSSG或L-胱氨酸的摄取和还原，导致细胞巯基含量增加10倍，使细胞内浓度升高至30至40 mM。变形菌细胞，以在细胞外介质和细胞质中产生还原环境。
Incubation of Streptococcus mutans cells with certain disulfide compounds resulted in accumulation of reduced sulfhydryl compounds in the extracellular medium or in both the medium and the cells. Oxidized lipoic acid and lipoamide competed for reduction. At high concentrations, these compounds were reduced at rates comparable to that of glucose metabolism, and all of the increase in sulfhydryls was in the medium. Cystamine did not compete with these compounds for reduction but was also reduced at high rates and low apparent affinity, and all of the cysteamine produced from cystamine accumulated in the medium. In contrast, glutathione disulfide (GSSG) and L-cystine were reduced slowly but with high apparent affinity, and 60 to 80% of the increase in sulfhydryls was intracellular. NADH-dependent lipoic acid or lipoamide reductase activity was present in the particulate (wall-plus-membrane) fraction, whereas NADPH-dependent GSSG reductase activity was present in the soluble (cytoplasmic) fraction. Two transport systems for disulfide and sulfhydryl compounds were distinguished. GSSG, L-cystine, and reduced glutathione competed for uptake. L-Cysteine was taken up by a separate system that also accepted L-penicillamine and D-cysteine as substrates. Uptake of glutathione or L-cysteine, or the uptake and reduction of GSSG or L-cystine, resulted in up to a 10-fold increase in cell sulfhydryl content that raised intracellular concentrations to between 30 and 40 mM. These reductase and transport systems enable S. mutans cells to create a reducing environment in both the extracellular medium and the cytoplasm.