Department of Chemistry and Biochemistry, University of California, Santa Barbara, California 93106, USA.
J Am Chem Soc. 2010 Jul 14;132(27):9240-3. doi: 10.1021/ja102221e.
Cysteine sulfenic acid CysS(O)H is shown to be formed for the reaction of cysteine (CysSH) with aqueous nitrite and the water-soluble ferriheme models Fe(III)(TPPS) (TPPS = meso-tetra(4-sulfonatophenyl)porphyrinato) or Fe(III)(TMPS) (TMPS = meso-tetra(sulfonatomesityl)porphyrinato) at pH 5.8 and 7.4. The other product is the respective ferrous nitrosyl complex Fe(II)(Por)(NO) (Por = TPPS or TMPS). Analogous oxygen atom transfers (OAT) were seen when glutathione (GSH) was used as the substrate. The sulfenic acids, CysS(O)H and GS(O)H, are transient species since they react rapidly with excess thiol to give the respective disulfides, so their presence as reactive intermediates was demonstrated by trapping with dimedone and detecting the resulting adduct using LC/MS. Preliminary kinetics studies are consistent with rate-limiting OAT from a ferric nitro complex Fe(III)(Por)(NO(2)(-)) to CysSH, although this reaction is complicated by a competing dead-end equilibrium to form the thiolate complex (Fe(III)(TPPS)(CysS(-)).
半胱氨酸亚磺酸 CysS(O)H 被证明是在 pH 值为 5.8 和 7.4 时，半胱氨酸 (CysSH) 与水合亚硝酸盐和水溶性 ferriheme 模型 Fe(III)(TPPS)（TPPS = 间四(4-磺酸钠苯基)卟啉）或 Fe(III)(TMPS)（TMPS = 间四(磺酸钠均三甲苯基)卟啉）反应形成的。另一个产物是相应的亚铁亚硝酰配合物 Fe(II)(Por)(NO)（Por = TPPS 或 TMPS）。当使用谷胱甘肽 (GSH) 作为底物时，也观察到类似的氧原子转移 (OAT)。亚磺酸，CysS(O)H 和 GS(O)H，是瞬态物种，因为它们与过量的硫醇快速反应生成相应的二硫化物，因此通过与二酮并用并使用 LC/MS 检测生成的加合物来证明它们作为反应中间体的存在。初步动力学研究表明，OAT 从 ferric nitro 配合物 Fe(III)(Por)(NO(2)(-)) 到 CysSH 是限速步骤，尽管该反应受到形成硫醇配合物（Fe(III)(TPPS)(CysS(-))）的竞争死端平衡的复杂化。
