Chae H Z, Rhee S G
Laboratory Biochemistry, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD 20892.
Biofactors. 1994 May;4(3-4):177-80.
Yeast and mammalian cells contain a 25 kDa enzyme that protects cellular components against oxidative damage from a system capable of generating reactive sulfur species, but not from a system that generates only reactive oxygen species. Yeast and rat cDNAs corresponding to this thiol-specific antioxidant (TSA) have been cloned and sequenced. Rat TSA is 65.3% identical and 76.2% similar to yeast TSA in amino acid sequence. A search of the GenBank database revealed 12 additional TSA-like proteins, which show sequence identity to rat TSA ranging from 31 to 76%. Except for the AhpC protein identified in Salmonella typhimurium, none of the TSA-like proteins is associated with known cellular functions. AhpC, which exhibits approximately 40% sequence identity to TSA, has been proposed to be a catalytic component of alkyl hydroperoxide reductase. Alignment of rat and yeast TSA with the TSA-like sequences revealed two conserved cysteine residues, one conserved in all 14 sequences and the other in 12 sequences. The most conserved cysteine is located in a well-conserved motif of (hydrophobic residue)6-Pro-non-conserved-residue-Asp-Phe-Thr-Phe-Val-Cys-Pro-Thr-Glu- hydrophobic residue. These results suggest that the TSA-like proteins of previously unknown function may represent a widely distributed family of antioxidants with functions similar to those of TSA and AhpC.
酵母和哺乳动物细胞含有一种25 kDa的酶，该酶可保护细胞成分免受能够产生活性硫物种的系统所造成的氧化损伤，但不能保护细胞免受仅产生活性氧物种的系统的氧化损伤。与这种硫醇特异性抗氧化剂（TSA）相对应的酵母和大鼠cDNA已被克隆和测序。大鼠TSA与酵母TSA在氨基酸序列上的同源性为65.3%，相似性为76.2%。对GenBank数据库的搜索揭示了另外12种TSA样蛋白，它们与大鼠TSA的序列同源性在31%至76%之间。除了在鼠伤寒沙门氏菌中鉴定出的AhpC蛋白外，TSA样蛋白均与已知的细胞功能无关。AhpC与TSA的序列同源性约为40%，已被认为是烷基过氧化氢还原酶的催化成分。大鼠和酵母TSA与TSA样序列的比对揭示了两个保守的半胱氨酸残基，一个在所有14个序列中保守，另一个在12个序列中保守。最保守的半胱氨酸位于一个高度保守的基序中：（疏水残基）6-Pro-非保守残基-Asp-Phe-Thr-Phe-Val-Cys-Pro-Thr-Glu-疏水残基。这些结果表明，以前功能未知的TSA样蛋白可能代表了一个广泛分布的抗氧化剂家族，其功能与TSA和AhpC相似。
