The mercuric and organomercurial detoxifying enzymes from a plasmid-bearing strain of Escherichia coli.
The mercuric and organomercurial detoxifying enzymes from a plasmid-bearing strain of Escherichia coli.
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来自携带质粒的大肠杆菌菌株的汞和有机汞解毒酶。
DOI：
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发表时间：
1978
影响因子：
4.8
通讯作者：
J. Schottel
中科院分区：
文献类型：
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作者：
J. Schottel
从携带质粒的大肠杆菌菌株J53-1（R831）中纯化了两种单独的酶，它们决定了对无机汞和有机汞的抗性。将Hg 2+还原为挥发性Hg 0的汞还原酶从French press破碎细胞的160，000 X g上清液中纯化约240倍。该酶含有结合的FAD，需要NADPH作为电子供体，并且需要巯基化合物的存在以获得活性。该还原酶的Km为13微米HgCl 2，在50 mM磷酸钠缓冲液中的最适pH为7.5，等电点为5.3，斯托克斯半径为50 A，分子量约为180，000。在十二烷基硫酸钠存在下通过凝胶电泳测定的亚基分子量约为63，000 +/-2，000。这些结果表明，天然酶是由三个相同的亚基。有机汞水解酶，打破汞-碳键的化合物，如甲基汞氯化物，乙酸苯汞，乙基汞氯化物，纯化约38倍以上的起始材料。该酶对氯化乙基汞的Km为0.56微米，对氯化甲基汞的Km为7.7微米，对乙酸苯汞的Km值为0.24微米和超过200微米。该水解酶具有5.5的等电点，需要EDTA和巯基化合物的存在以获得活性，具有24 A的斯托克斯半径，并且具有约43，000 +/-4，000的分子量。
Two separate enzymes, which determine resistance to inorganic mercury and organomercurials, have been purified from the plasmid-bearing Escherichia coli strain J53-1(R831). The mercuric reductase that reduces Hg2+ to volatile Hg0 was purified about 240-fold from the 160,000 X g supernatant of French press disrupted cells. This enzyme contains bound FAD, requires NADPH as an electron donor, and requires the presence of a sulfhydryl compound for activity. The reductase has a Km of 13 micron HgCl2, a pH optimum of 7.5 in 50 mM sodium phosphate buffer, an isoelectric point of 5.3, a Stokes radius of 50 A, and a molecular weight of about 180,000. The subunit molecular weight, determined by gel electrophoresis in the presence of sodium dodecyl sulfate, is about 63,000 +/- 2,000. These results suggest that the native enzyme is composed of three identical subunits. The organomercurial hydrolase, which breaks the mercury-carbon bond in compounds such as methylmercuric chloride, phenylmercuric acetate, and ethylmercuric chloride, was purified about 38-fold over the starting material. This enzyme has a Km of 0.56 micron for ethylmercuric chloride, a Km of 7.7 micron for methylmercuric chloride, and two Km values of 0.24 micron and over 200 micron for phenylmercuric acetate. The hydrolase has an isoelectric point of 5.5, requires the presence of EDTA and a sulfhydryl compound for activity, has a Stokes radius of 24 A, and has a molecular weight of about 43,000 +/- 4,000.