Turjman N, Nair P P
Cancer Res. 1981 Sep;41(9 Pt 2):3761-3.
Lithocholic acid, a monohydroxy secondary bile acid, is present in tissues in two forms. One form is extractable with 95% ethanol-0.1% ammonia (soluble lithocholate), and the other form is firmly bound to tissue residues and can be released only by the bile salt-deconjugating enzyme, clostridial cholanoylamino acid hydrolase (tissue-bound lithocholate). Studies on bile salt-protein interactions revealed that lithocholic acid had amino group-modifying activity specifically directed against the basic side group of lysine residues. Degradative procedures yielded N-epsilon-lithocholyllysine, confirmed by comparison with the authentic compound synthesized in our laboratories. Studies on the distribution of tissue-bound lithocholate in tissues have revealed high concentrations of this form of lithocholate in livers of rats treated with the carcinogen, methylazoxymethanol. In light of these observations, the role of bile acids, and specifically lithocholic acid, as promoters of tumorigenesis must be further investigated.
石胆酸是一种单羟基次级胆汁酸，在组织中以两种形式存在。一种形式可用95%乙醇 - 0.1%氨提取（可溶性石胆酸盐），另一种形式则牢固地结合于组织残渣，只有通过胆汁盐去结合酶——梭菌属胆酰氨基酸水解酶（组织结合型石胆酸盐）才能释放出来。对胆汁盐 - 蛋白质相互作用的研究表明，石胆酸具有专门针对赖氨酸残基碱性侧链的氨基修饰活性。降解过程产生了N - ε - 石胆酰赖氨酸，通过与我们实验室合成的 authentic 化合物比较得以证实。对组织结合型石胆酸盐在组织中的分布研究表明，在用致癌物甲基偶氮甲醇处理的大鼠肝脏中，这种形式的石胆酸盐浓度很高。鉴于这些观察结果，必须进一步研究胆汁酸，特别是石胆酸作为肿瘤发生促进剂的作用。
