Marschall H U, Egestad B, Matern H, Matern S, Sjövall J
Department of Physiological Chemistry, Karolinska Institutet, Stockholm, Sweden.
J Biol Chem. 1989 Aug 5;264(22):12989-93.
Bile acids were extracted from human urine and were separated into groups of nonamidated and glycine- and taurine-conjugated compounds. Each group was subfractionated in a reversed-phase high performance liquid chromatography system, and the fractions were analyzed by negative ion fast atom bombardment mass spectrometry and also by gas chromatography-mass spectrometry after enzymatic removal of glycine and taurine moieties. The major glycosides of the non-amidated bile acids were more polar than reference bile acid glucosides and gave quasimolecular ions at m/z 592, 594, and 610 consistent with N-acetylglucosaminides of unsaturated dihydroxy and saturated di- and trihydroxy bile acids. Gas chromatography-mass spectrometry analyses of methyl ester trimethylsilyl ether derivatives showed fragments typical for N-acetylglucosaminides (m/z 173 and 186) in addition to those also given by glucosides (m/z 204 and 217). The N-acetylglucosaminides were inert toward alpha- and beta-glucosidase but were cleaved completely with N-acetylglucosaminidase. The released sugar moiety was identified as N-acetylglucosamine. One of the liberated bile acids was identified as ursodeoxycholic acid. The other acids were not identical to any known primary or secondary bile acid in humans. Fast atom bombardment mass spectrometry analyses of the glycine-and taurine-conjugated bile acid glycosides only showed ions consistent with the presence of glucosides (m/z 626 and 676). These compounds were sensitive only toward beta-glucosidase which liberated a trihydroxy bile acid as the major compound. Based on the recover of 13C- and 14C-labeled chenodeoxycholic acid glucoside added as internal standard, the daily excretion of nonamidated bile acid glycosides was estimated to be about 137 micrograms or 0.29 mumol, N-acetylglucosaminides constituting about 90%. The daily excretion of the glucosides of amidated bile acids was about 150 micrograms or 0.25 mumol, glycine conjugates constituting about 90%.
从人尿中提取胆汁酸，并将其分为未酰胺化、甘氨酸结合和牛磺酸结合的化合物组。每组在反相高效液相色谱系统中进行细分，各馏分通过负离子快原子轰击质谱分析，并且在酶法去除甘氨酸和牛磺酸部分后通过气相色谱 - 质谱分析。未酰胺化胆汁酸的主要糖苷比参考胆汁酸葡糖苷极性更大，在m/z 592、594和610处给出准分子离子，与不饱和二羟基、饱和二羟基和三羟基胆汁酸的N - 乙酰葡糖胺苷一致。甲酯三甲基硅醚衍生物的气相色谱 - 质谱分析显示，除了葡糖苷给出的碎片（m/z 204和217）外，还有N - 乙酰葡糖胺苷典型的碎片（m/z 173和186）。N - 乙酰葡糖胺苷对α - 和β - 葡糖苷酶呈惰性，但能被N - 乙酰葡糖胺酶完全裂解。释放出的糖部分被鉴定为N - 乙酰葡糖胺。释放出的胆汁酸之一被鉴定为熊去氧胆酸。其他酸与人类任何已知的初级或次级胆汁酸都不相同。甘氨酸和牛磺酸结合的胆汁酸糖苷的快原子轰击质谱分析仅显示与葡糖苷存在一致的离子（m/z 626和676）。这些化合物仅对β - 葡糖苷酶敏感，该酶释放出一种三羟基胆汁酸作为主要化合物。以内标形式添加的13C - 和14C - 标记的鹅去氧胆酸葡糖苷的回收率为基础，估计未酰胺化胆汁酸糖苷的每日排泄量约为137微克或0.29微摩尔，N - 乙酰葡糖胺苷约占90%。酰胺化胆汁酸葡糖苷的每日排泄量约为150微克或0.25微摩尔，甘氨酸结合物约占90%。
