Leung K H, Post G B, Menzel D B
Toxicol Appl Pharmacol. 1985 Mar 15;77(3):388-94. doi: 10.1016/0041-008x(85)90178-4.
Glutathione S-sulfonate (GSSO3H) is a reaction product of glutathione disulfide (GSSG) and sulfite, the hydrated form of sulfur dioxide. In the present study, GSSO3H was found to be a potent competitive inhibitor of the glutathione S-transferases (GST) in the rat liver (Ki = 14 microM) and lung (Ki = 9 microM), and in human lung tumor-derived A549 cells (Ki = 4 microM). GSSO3H was also reduced by a cytosolic enzyme in the rat liver (Km = 313 microM) and lung (Km = 200 microM), and human lung A549 cells (Km = 400 microM). These results suggest that SO2 may affect the detoxification of xenobiotic compounds by inhibiting, via formation of GSSO3H, the enzymatic conjugation of glutathione (GSH) and reactive electrophiles. Although GSSO3H can be enzymatically degraded, the high substrate Km value suggests that this compound may not be readily reduced at low concentrations.
谷胱甘肽S-磺酸酯（GSSO3H）是谷胱甘肽二硫化物（GSSG）与亚硫酸盐（二氧化硫的水合形式）的反应产物。在本研究中，发现GSSO3H是大鼠肝脏（Ki = 14微摩尔）和肺脏（Ki = 9微摩尔）以及人肺肿瘤来源的A549细胞（Ki = 4微摩尔）中谷胱甘肽S-转移酶（GST）的强效竞争性抑制剂。GSSO3H还可被大鼠肝脏（Km = 313微摩尔）、肺脏（Km = 200微摩尔）以及人肺A549细胞（Km = 400微摩尔）中的一种胞质酶还原。这些结果表明，二氧化硫可能通过形成GSSO3H抑制谷胱甘肽（GSH）与活性亲电试剂的酶促结合，从而影响外源性化合物的解毒作用。尽管GSSO3H可被酶促降解，但高底物Km值表明该化合物在低浓度时可能不易被还原。
