Faculty of Biotechnology, Fukui Prefectural University, Eiheiji-cho, Fukui, Japan.
School of Pharmacy, Hyogo University of Health Sciences, Kobe, Hyogo, Japan.
Amino Acids. 2018 Jan;50(1):117-124. doi: 10.1007/s00726-017-2498-y. Epub 2017 Oct 10.
Taurine is an abundant beta-amino acid found in high concentration in mammalian tissues. Taurine possesses many beneficial functions in mammalian cells. There are also a variety of taurine-conjugated products formed between taurine and bile acids, fatty acids, chloramine, mitochondrial tRNA, etc., and some of these have been identified as functional compounds. In the present study, we identified taurine-conjugated metabolites using LC-MS-based metabolome analysis of heart extracts prepared from hearts of wild-type and taurine transporter-knockout (TauTKO) mice, the latter being severely taurine deficient. Comparison analysis of metabolites identified taurine-containing dipeptides, including glutamyltaurine, aspartyltaurine, isoleucyltaurine, and leucyltaurine, which are present in wild-type but not TauTKO hearts. Acyltaurines (taurine-conjugated fatty acids) and taurine-conjugated bile acids were also detected, with levels unchanged in the TauTKO heart in comparison to the wild-type heart. These results demonstrate that taurine exists not only in the standard free form within the heart, but also in multiple conjugated forms, whose functions in the heart remain to be discovered.
牛磺酸是一种丰富的β-氨基酸，在哺乳动物组织中高浓度存在。牛磺酸在哺乳动物细胞中具有许多有益的功能。牛磺酸还与胆汁酸、脂肪酸、氯胺、线粒体 tRNA 等形成各种牛磺酸缀合物，其中一些已被鉴定为具有功能的化合物。在本研究中，我们使用基于 LC-MS 的代谢组学分析方法，对来自野生型和牛磺酸转运体敲除（TauTKO）小鼠心脏提取物进行分析，鉴定了牛磺酸缀合代谢物，后者严重缺乏牛磺酸。对鉴定出的代谢物进行比较分析，发现了含有牛磺酸的二肽，包括谷氨酰牛磺酸、天冬氨酰牛磺酸、异亮氨酰牛磺酸和亮氨酰牛磺酸，这些二肽存在于野生型心脏中，但不存在于 TauTKO 心脏中。还检测到酰基牛磺酸（牛磺酸缀合脂肪酸）和牛磺酸缀合胆汁酸，其在 TauTKO 心脏中的水平与野生型心脏相比没有变化。这些结果表明，牛磺酸不仅以标准游离形式存在于心脏中，还以多种缀合形式存在，其在心脏中的功能尚待发现。
