title: Analysis of bile acid glutathione thioesters by liquid chromatography/electrospray ionization-tandem mass spectrometry.
abstract: The formation of thioester-linked glutathione (GSH) conjugates of bile acids (BAs) is presumed to occur via trans-acylation reactions between GSH and reactive acyl-linked metabolites of BAs. The present study examines the chemical reactivity of cholyl-adenylate and cholyl-CoA thioester, acyl-linked metabolites of cholic acid (CA), with GSH to form CA-GSH conjugate in vitro. The authentic specimen of CA-GSH was synthesized along with GSH conjugates of four common BAs found in the human body. Their structures were confirmed by proton-nuclear magnetic resonance spectroscopy and electrospray ionization (ESI)-tandem mass spectrometry in positive- and negative-ion modes. Incubation of cholyl-adenylate or cholyl-CoA thioester with GSH was carried out at pH 7.5 and 37 degrees C for 30 min, with analysis of the reaction mixture by liquid chromatography/ESI-tandem mass spectrometry, where CA-GSH was detected on the product ion mass chromatograms monitored with stable and abundant dehydrated positive-ion [M+HH(2)O](+) at m/z 680.3 and fragmented negative-ion [GSHH](-) at m/z 306.0, and was definitely identified by CID spectra by comparison with those of the authentic sample. The results show that both cholyl-adenylate and cholyl-CoA thioester are able to acylate GSH in vitro.
authors.affiliation: Faculty of Pharmaceutical Sciences, Kinki University, Higashi, Osaka, Japan. mitamura@phar.kindai.ac.jp
authors.forename: Kuniko
authors.initials: K
authors.lastname: Mitamura
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Sogabe
authors.forename: Hironori
authors.initials: H
authors.lastname: Sakanashi
authors.forename: Saai
authors.initials: S
authors.lastname: Watanabe
authors.forename: Toshihiro
authors.initials: T
authors.lastname: Sakai
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Yamaguchi
authors.forename: Tateaki
authors.initials: T
authors.lastname: Wakamiya
authors.forename: Shigeo
authors.initials: S
authors.lastname: Ikegawa
mesh_terms: D000249:Adenosine Monophosphate / Q000031:analogs & derivatives / Q000737:chemistry; D001647:Bile Acids and Salts / Q000737:chemistry* / Q000378:metabolism; D019826:Cholic Acid / Q000737:chemistry; D002793:Cholic Acids / Q000737:chemistry; D002853:Chromatography, Liquid; D005978:Glutathione / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D006863:Hydrogen-Ion Concentration; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D053719:Tandem Mass Spectrometry; D013696:Temperature
chemical_list: D001647:Bile Acids and Salts; D002793:Cholic Acids; C117584:cholyl-adenylate; D000249:Adenosine Monophosphate; D019826:Cholic Acid; D005978:Glutathione