The utilization of alanine, glutamic acid, and serine as amino acid substrates for glycine N-acyltransferase

The conjugation of benzoyl‐CoA with the aliphatic and acidic amino acids by glycine N‐acyltransferase, as well as the amides of the latter group, was investigated. Bovine and human liver benzoyl‐amino acid conjugation were investigated using electrospray ionization tandem mass spectrometry (ESI‐MS‐MS). Bovine glycine N‐acyltransferase catalyzed conjugation of benzoyl‐CoA with Gly (KmGly = 6.2 mM), Asn (KmAsn = 129 mM), Gln (KmGln = 353 mM), Ala (KmAla = 1573 mM), Glu (KmGlu = 1148 mM) as well as Ser in a sequential mechanism. In the case of the human form, conjugation with Gly (KmGly = 6.4 mM), Ala (KmAla = 997 mM), and Glu was detected. The presence of these alternative conjugates did not inhibit bovine glycine N‐acyltransferase activity significantly. Considering the relatively low levels at which these conjugates are formed, it is unlikely that they will have a significant contribution to acyl‐amino acid conjugation under normal conditions in vivo. However, their cumulative contribution to acyl‐amino acid conjugation under metabolic disease states may prove to have a useful contribution to detoxification of elevated acyl‐CoAs. © 2000 John Wiley & Sons, Inc. J Biochem Toxicol 14: 102–109, 2000