Laboratory of Biochemistry, National Heart, Lung, and Blood Institute, Bethesda, MD 20892-8012, USA.
Proc Natl Acad Sci U S A. 2011 Jun 28;108(26):10472-7. doi: 10.1073/pnas.1101275108. Epub 2011 Jun 13.
Methionine sulfoxide reductase A (MsrA) catalyzes the reduction of methionine sulfoxide to methionine and is specific for the S epimer of methionine sulfoxide. The enzyme participates in defense against oxidative stresses by reducing methionine sulfoxide residues in proteins back to methionine. Because oxidation of methionine residues is reversible, this covalent modification could also function as a mechanism for cellular regulation, provided there exists a stereospecific methionine oxidase. We show that MsrA itself is a stereospecific methionine oxidase, producing S-methionine sulfoxide as its product. MsrA catalyzes its own autooxidation as well as oxidation of free methionine and methionine residues in peptides and proteins. When functioning as a reductase, MsrA fully reverses the oxidations which it catalyzes.
甲硫氨酸亚砜还原酶 A（MsrA）催化甲硫氨酸亚砜还原为甲硫氨酸，并且对甲硫氨酸亚砜的 S 对映异构体具有特异性。该酶通过将蛋白质中甲硫氨酸亚砜残基还原为甲硫氨酸来参与抵御氧化应激。因为甲硫氨酸残基的氧化是可逆的，这种共价修饰也可以作为细胞调节的一种机制，只要存在立体特异性甲硫氨酸氧化酶。我们表明，MsrA 本身就是一种立体特异性甲硫氨酸氧化酶，其产物为 S-甲硫氨酸亚砜。MsrA 催化自身的自动氧化以及游离甲硫氨酸和肽和蛋白质中甲硫氨酸残基的氧化。当作为还原酶时，MsrA 完全逆转其催化的氧化反应。
