A Comprehensive Analysis of Selenium-Binding Proteins in the Brain Using Its Reactive Metabolite
作者:Sakura Yoshida、Eriko Hori、Sakiko Ura、Mamoru Haratake、Takeshi Fuchigami、Morio Nakayama
DOI:10.1248/cpb.c15-00689
日期:——
The intracellular metabolism of selenium in the brain currently remains unknown, although the antioxidant activity of this element is widely acknowledged to be important in maintaining brain functions. In this study, a comprehensive method for identifying the selenium-binding proteins using PenSSeSPen as a model of the selenium metabolite, selenotrisulfide (RSSeSR, STS), was applied to a complex cell lysate generated from the rat brain. Most of the selenium from L-penicillamine selenotrisulfide (PenSSeSPen) was captured by the cytosolic protein thiols in the form of STS through the thiol-exchange reaction (R-SH+PenSSeSPen→R-SSeSPen+PenSH). The cytosolic protein species, which reacted with the PenSSeSPen mainly had a molecular mass of less than 20 kDa. A thiol-containing protein at m/z 15155 in the brain cell lysate was identified as the cystatin-12 precursor (CST12) from a rat protein database search and a tryptic fragmentation experiment. CST12 belongs to the cysteine proteinase inhibitors of the cystatin superfamily that are of interest in mechanisms regulating the protein turnover and polypeptide production in the central nervous system and other tissues. Consequently, CST12 is suggested to be one of the cytosolic proteins responsible for the selenium metabolism in the brain.
尽管人们普遍认为硒元素的抗氧化活性对于维持大脑功能非常重要,但硒在大脑中的细胞内代谢目前仍不清楚。在本研究中,使用 PenSSeSPen 作为硒代谢物三硫化硒 (RSSeSR、STS) 的模型来鉴定硒结合蛋白的综合方法,应用于大鼠大脑产生的复杂细胞裂解物。 L-青霉胺硒代三硫化物 (PenSSeSPen) 中的大部分硒通过硫醇交换反应 (R-SH+PenSSeSPen→R-SSeSPen+PenSH) 以 STS 的形式被胞质蛋白硫醇捕获。与PenSSeSPen反应的胞质蛋白种类主要具有小于20kDa的分子量。通过大鼠蛋白质数据库搜索和胰蛋白酶裂解实验,脑细胞裂解物中 m/z 15155 的含硫醇蛋白质被鉴定为胱抑素 12 前体 (CST12)。 CST12 属于半胱氨酸蛋白酶抑制剂超家族的半胱氨酸蛋白酶抑制剂,其对调节中枢神经系统和其他组织中蛋白质周转和多肽产生的机制感兴趣。因此,CST12 被认为是负责大脑中硒代谢的胞质蛋白之一。