Bioactivation mechanism of L-thiomorpholine-3-carboxylic acid.
Bioactivation mechanism of L-thiomorpholine-3-carboxylic acid.
复制标题
L-硫代吗啉-3-羧酸的生物活化机制。
DOI：
10.1016/0003-9861(89)90516-x
复制
发表时间：
1989
影响因子：
3.9
通讯作者：
Anders,MW
中科院分区：
文献类型：
--
作者：
Webster,KD;Anders,MW
1-硫代吗啉-3-羧酸（1-TMC）是S-（2-氯乙基）-L-半胱氨酸的环化类似物，具有体外细胞毒性和体内肾毒性。为了确定l-TMC是否可能在S-（2-氯乙基）-l-半胱氨酸诱导的毒性中起作用，在分离的大鼠肾细胞中研究了l-TMC的细胞毒性。肾阴离子转运系统抑制剂丙磺舒和l-氨基酸氧化酶底物l-α-羟基异己酸可抑制l-TMC诱导的细胞毒性。大鼠肾脏胞质溶胶催化fl-TMC代谢为在300 nm处吸收的产物。在300 nm处吸光度的增加伴随着耗氧量的增加，并被α-羟基异己酸抑制;此外，通过加入氰化钾或硼氢化钠，代谢产物的吸光度被淬灭，这表明形成了亚胺。当l-TMC与大鼠肾胞质溶胶一起孵育并在孵育期结束时加入硼氘化钠时，通过气相色谱/质谱法分析l-TMC的叔丁基二甲基甲硅烷基酯显示[2 H]TMC的形成，表明亚胺5，6-二氢-2H-1，4-噻嗪-3-羧酸的中间体形成;化学合成的TMC亚胺显示类似的行为。从大鼠肾脏中分离纯化了一种负责α-TMC代谢的酶，经鉴定为L-氨基酸氧化酶。这些观察结果表明l-氨基酸氧化酶在fl-TMC的生物活化和细胞毒性中的作用。
l-Thiomorpholine-3-carboxylic acid (l-TMC) is a cyclized analog ofS-(2-chloroethyl)-l-cysteine, which is cytotoxicin vitroand nephrotoxicin vivo. To determine whetherl-TMC may play a role inS-(2-chloroethyl)-l-cysteine-induced toxicity, the cytotoxicity ofl-TMC was studied in isolated rat kidney cells.l-TMC produced time- and concentration-dependent cytotoxicity. Probenecid, an inhibitor of the renal anion transport system, andl-α-hydroxyisocaproic acid, a substrate forl-amino acid oxidase, inhibitedl-TMC-induced cytotoxicity. Rat kidney cytosol catalyzed the metabolism ofl-TMC to a product absorbing at 300 nm. The increase in absorbance at 300 nm was accompanied by an increase in oxygen consumption and was inhibited byl-α-hydroxyisocaproic acid; moreover, the absorbance of the metabolite was quenched by addition of potassium cyanide or sodium borohydride, which indicated the formation of an imine. Whenl-TMC was incubated with rat kidney cytosol and sodium borodeuteride was added at the end of the incubation period, analysis by gas chromatography/mass spectrometry of thetert-butyldimethylsilyl ester ofl-TMC showed the formation of [2H]TMC, indicating the intermediate formation of the imine 5,6-dihydro-2H-1,4-thiazine-3-carboxylic acid; chemically synthesized TMC imine showed similar behavior. The enzyme responsible for the metabolism ofl-TMC was purified from rat kidney and was identified asl-amino acid oxidase. These observations indicate a role forl-amino acid oxidase in the bioactivation and cytotoxicity ofl-TMC.