THIOREDOXIN-LINKED THIOL PEROXIDASE FROM PERIPLASMIC SPACE OF ESCHERICHIA-COLI
THIOREDOXIN-LINKED THIOL PEROXIDASE FROM PERIPLASMIC SPACE OF ESCHERICHIA-COLI
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DOI：
10.1074/jbc.270.48.28635
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发表时间：
1995-12-01
影响因子：
4.8
通讯作者：
KIM, IH
中科院分区：
文献类型：
--
作者：
CHA, MK;KIM, HK;KIM, IH
在大肠杆菌中纯化了三种不同分子量（24，22和20 kDa）的抗氧化蛋白。这些蛋白质表现出对谷氨酰胺合成酶活性失活和通过能够产生活性氧的金属催化氧化系统切割DNA的预防作用。它们的抗氧化活性得到巯基还原等价物如二硫苏糖醇的支持。对24-kDa和22-kDa蛋白的氨基端氨基酸序列和免疫印迹分析表明，24-kDa蛋白是先前鉴定的大肠杆菌22-kDa亚基（AhpC）的22-kDa蛋白的完整形式。coli烷基过氧化氢还原酶（AhpC/AhpF）。我们分离并测序了一个E. coli基因组DNA片段，编码20-kDa蛋白。20 kDa的蛋白质与AhpC的推导的氨基酸序列的比较显示没有序列同源性。对数据库的搜索表明，20-kDa蛋白是一种新型的抗氧化酶。这种新的20-kDa蛋白的合成增加，在生长过程中的氧应激反应。20-kDa蛋白主要存在于E.而24-kDa的AhpC主要存在于基质中。20-kDa的蛋白质功能性地连接到硫氧还蛋白作为体内巯基再生系统，并发挥过氧化物酶活性。这种20 kDa的蛋白质因此被命名为“巯基过氧化物酶”，它可以作为一种抗氧化酶，在过氧化氢酶和过氧化物酶缺乏的E.杆菌
Three different molecular masses (24, 22, and 20 kDa) of antioxidant proteins were purified in Escherichia coli. These proteins exhibited the preventive effects against the inactivation of glutamine synthetase activity and the cleavage of DNA by a metal-catalyzed oxidation system capable of generating reactive oxygen species. Their antioxidant activities were supported by a thiol-reducing equivalent such as dithiothreitol. Analysis of the amino-terminal amino acid sequences and the immunoblots between 24 and 22-kDa proteins indicates that the 24-kDa protein is an intact form of the 22-kDa protein that was previously identified 22-kDa subunit (AhpC) of E. coli alkyl hydroperoxide reductase (AhpC/AhpF). We isolated and sequenced an E. coli genomic DNA fragment that encodes 20-kDa protein. Comparison of the deduced amino acid sequence of the 20-kDa protein with that of AhpC revealed no sequence homology. A search of a data bank showed that the 20-kDa protein is a new type of antioxidant enzyme. The synthesis of this novel 20-kDa protein was increased in response to oxygen stress during growth. The 20-kDa protein resides mainly in the periplasmic space of E. coli, whereas the 24-kDa AhpC resides mainly in the matrix. The 20-kDa protein was functionally linked to the thioredoxin as an in vivo thiol-regenerating system and exerted a peroxidase activity. This 20-kDa protein is thus named ''thiol peroxidase,'' which could act as an antioxidant enzyme removing peroxides or H2O2 within the catalase- and peroxidase-deficient periplasmic space of E. coli.