Department of Pediatrics, Peking University First Hospital, Beijing 100034, China.
Biochem Biophys Res Commun. 2011 Nov 11;415(1):61-7. doi: 10.1016/j.bbrc.2011.10.012. Epub 2011 Oct 12.
While sulfur dioxide (SO(2)) has been previously known for its toxicological effects, it is now known to be produced endogenously in mammals from sulfur-containing amino acid L-cysteine. L-cysteine is catalyzed by cysteine dioxygenase (CDO) to L-cysteinesulfinate, which converts to β-sulfinylpyruvate through transamination by aspartate aminotransferase (AAT), and finally spontaneously decomposes to pyruvate and SO(2). The present study explored endogenous SO(2) production, and AAT and CDO distribution in different rat tissue. SO(2) content was highest in stomach, followed by tissues in the right ventricle, left ventricle, cerebral gray matter, pancreas, lung, cerebral white matter, renal medulla, spleen, renal cortex and liver. AAT activity and AAT1 mRNA expression were highest in the left ventricle, while AAT1 protein expression was highest in the right ventricle. AAT2 and CDO mRNA expressions were both highest in liver tissue. AAT2 protein expression was highest in the renal medulla, but CDO protein expression was highest in liver tissue. In all tissues, AAT1 and AAT2 were mainly distributed in the cytoplasm rather than the nucleus. These observed differences among tissues endogenously generating SO(2) and associated enzymes are important in implicating the discovery of SO(2) as a novel endogenous signaling molecule.
虽然二氧化硫（SO(2)）以前因其毒理学效应而为人所知，但现在已知它是哺乳动物内源性地从含硫氨基酸 L-半胱氨酸中产生的。L-半胱氨酸被半胱氨酸双加氧酶（CDO）催化生成 L-半胱氨酸亚砜，然后通过天冬氨酸氨基转移酶（AAT）的转氨基作用转化为β-亚磺酰丙酮酸，最后自发分解为丙酮酸和 SO(2)。本研究探索了内源性 SO(2)的产生以及 AAT 和 CDO 在不同大鼠组织中的分布。SO(2)含量在胃中最高，其次是右心室、左心室、大脑灰质、胰腺、肺、大脑白质、肾髓质、脾、肾皮质和肝。AAT 活性和 AAT1mRNA 表达在左心室最高，而 AAT1 蛋白表达在右心室最高。AAT2 和 CDO mRNA 表达在肝组织中均最高。AAT2 蛋白表达在肾髓质中最高，但 CDO 蛋白表达在肝组织中最高。在所有组织中，AAT1 和 AAT2 主要分布在细胞质中，而不是细胞核中。这些观察到的内源性产生 SO(2)和相关酶的组织之间的差异对于暗示 SO(2)作为一种新型内源性信号分子的发现非常重要。
