Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA.
Biochemistry. 2013 Aug 20;52(33):5514-6. doi: 10.1021/bi400741c. Epub 2013 Aug 12.
Selenoprotein S (SelS, VIMP) is an intrinsically disordered enzyme that utilizes selenocysteine to catalyze the reduction of disulfide bonds and peroxides. Here it is demonstrated that selenocysteine is the residue oxidized by the peroxide substrate. It is possible to trap the reaction intermediate selenenic acid when the resolving cysteine is mutated. The selenocysteine allows SelS to rapidly re-form its selenenylsulfide bond following its reduction, and to resist inactivation by H2O2. We propose that SelS's peroxidase mechanism is similar to that of atypical 2-Cys peroxiredoxin and that selenocysteine allows SelS to sustain activity under oxidative stress.
硒蛋白 S（SelS，VIMP）是一种固有无序的酶，利用硒代半胱氨酸催化二硫键和过氧化物的还原。本文证明了过氧化物底物氧化的残基是硒代半胱氨酸。当解析半胱氨酸发生突变时，可以捕获反应中间体硒代磺酸。硒代半胱氨酸允许 SelS 在还原后快速重新形成其硒代亚磺酰硫键，并抵抗 H2O2 的失活。我们提出 SelS 的过氧化物酶机制类似于非典型 2-Cys 过氧化物酶，并且硒代半胱氨酸允许 SelS 在氧化应激下维持活性。
