Liquid Chromatography/Mass Spectrometric Characterization of Non-enzymatic Acylation of Amino or Thiol Groups of Bionucleophiles by the Cholyl-adenylate or Cholyl-CoA Thioester

摘要

Acyl-adenylates and acyl-CoA thioesters of bile acids are electrophilic acyl-linked metabolites which can undergo transacylation reactions with amino- and thiol-groups of nucleophilic groups on acceptor molecules such as amino acids, peptide, and proteins. However, the chemical reactivity of these molecules towards amino- and thiol-groups in the bionucleophiles is still not fully characterized. Therefore, we have compared the chemical (non-enzymatic) reactivity of cholyl-adenylate (CA-AMP) with that of cholyl-CoA thioester (CA-CoA) towards four biologically relevant bionucleophiles; glutathione (GSH), N-acetylcystein (NAC), taurine, and glycine at pH 7.4 with the use of an equimolar mixture of CA-CoA and [2,2,4,4-d_(4)]-CA-AMP (d_(4)-CA-AMP) (Fig. 1). The transacylation products from these substrates were characterized by LC/ESI-MS/MS.