title: Detection of beta-carbanion formation during kynurenine hydrolysis catalyzed by Pseudomonas marginalis kynureninase.
abstract: 2-Amino-4-hydroxy-4-phenylbutyric acid has been shown to be formed during the Pseudomonas marginalis kynureninase-catalyzed hydrolysis of kynurenine in the presence of benzaldehyde and pyridoxal phosphate. The formation of 2-amino-4-hydroxy-4-phenylbutyric acid is the first demonstration, to our knowledge, of the controlled trapping of an amino acid beta-carbanion generated either chemically or enzymatically, and is perhaps the best empirical evidence to date that enzyme mechanisms can proceed through a beta-carbanionic intermediate. The lifetime of the beta-carbanionic alanyl intermediate generated by kynureninase is of sufficient duration to allow reaction with benzaldehyde. Other aromatic, but no aliphatic, aldehydes will undergo electrophilic addition with kynureninase-generated beta-carbanionic alanyl intermediates to form the corresponding amino acid.
mesh_terms: D001547:Benzaldehydes / Q000378:metabolism; D055598:Chemical Phenomena; D002621:Chemistry; D006867:Hydrolases / Q000378:metabolism*; D006868:Hydrolysis; D007737:Kynurenine / Q000378:metabolism*; D009682:Magnetic Resonance Spectroscopy; D009952:Ornithine / Q000378:metabolism; D011549:Pseudomonas / Q000201:enzymology*; D011773:Pyruvates / Q000378:metabolism; D019289:Pyruvic Acid
chemical_list: D001547:Benzaldehydes; D011773:Pyruvates; D007737:Kynurenine; D019289:Pyruvic Acid; D009952:Ornithine; D006867:Hydrolases; C021480:kynureninase; C032175:benzaldehyde