Rhee S G, Jeong W, Chang T-S, Woo H A
Division of Life and Pharmaceutical Sciences, Ewha Womans University, Seoul, Korea.
Kidney Int Suppl. 2007 Aug(106):S3-8. doi: 10.1038/sj.ki.5002380.
Peroxiredoxin (Prx) is a family of bifunctional proteins that exhibit peroxidase and chaperone activities. Prx proteins contain a conserved Cys residue that undergoes a redox change between thiol and disulfide states. 2-Cys Prx enzymes, a subgroup of Prx family, are intrinsically susceptible to reversible hyperoxidation to cysteine sulfinic acid during catalysis. Cysteine hyperoxidation of Prx was shown to result in loss of peroxidase activity and a concomitant gain of chaperone activity. Reduction of sulfinic Prx enzymes, the first known biological example of such a reaction, is catalyzed by sulfiredoxin (Srx) in the presence of ATP. Srx appears to exist solely to support the reversible sulfinic modification of 2-Cys Prx enzymes. Srx specifically binds to 2-Cys Prx enzymes by recognizing several critical surface-exposed residues of the Prxs, and transfer the gamma-phosphate of ATP to their sulfinic moiety, using its conserved cysteine as the phosphate carrier. The resulting sulfinic phosphoryl ester is reduced to cysteine after oxidation of four thiol equivalents.
过氧化物酶（Prx）是一类具有过氧化物酶和伴侣活性的双功能蛋白家族。Prx蛋白含有一个保守的半胱氨酸残基，该残基在硫醇和二硫键状态之间发生氧化还原变化。2-半胱氨酸Prx酶是Prx家族的一个亚组，在催化过程中本质上易发生可逆的过度氧化，生成半胱氨酸亚磺酸。已证明Prx的半胱氨酸过度氧化会导致过氧化物酶活性丧失，并伴随伴侣活性增加。亚磺酸Prx酶的还原是这种反应的第一个已知生物学实例，在ATP存在下由硫氧还蛋白（Srx）催化。Srx似乎仅为支持2-半胱氨酸Prx酶的可逆亚磺酸修饰而存在。Srx通过识别Prx的几个关键表面暴露残基与2-半胱氨酸Prx酶特异性结合，并利用其保守的半胱氨酸作为磷酸载体，将ATP的γ-磷酸转移到它们的亚磺酸部分。在四个硫醇当量氧化后，生成的亚磺酸磷酯被还原为半胱氨酸。
