title: Photoaffinity labeling of Klebsiella aerogenes citrate lyase by p-azidobenzoyl coenzyme A.
abstract: p-Azidobenzoyl coenzyme A functions as a linear competitive inhibitor for (3S)-citryl-CoA in the citryl-CoA oxaloacetate-lyase reaction catalyzed by the Klebsiella aerogenes deacetylcitrate lyase complex (Ki = 80 microM; (3S)-citryl-CoA Km = 67 microM). Inactivation is irreversible on photolysis of p-azidobenzoyl-CoA in the presence of the deacetylcitrate lyase complex. Mg2+ is not required for the inactivation. Inactivation is blocked by (3S)-citryl-CoA in the presence of ethylenediaminetetraacetic acid. p-Azidobenzoyl-CoA has no effect on the acetyl-CoA:citrate CoA transferase activity of both the deacetylcitrate lyase complex and its isolated transferase subunit. The stoichiometry of the CoA ester binding has been investigated by the use of p-azido[14C]benzoyl-CoA as a photoaffinity reagent. The labeling is exclusively on the lyase beta subunit of the citrate lyase complex.
mesh_terms: D000214:Acyl Coenzyme A / Q000494:pharmacology*; D000345:Affinity Labels / Q000494:pharmacology*; D001386:Azides; D001665:Binding Sites; D004492:Edetic Acid / Q000494:pharmacology; D007700:Kinetics; D007711:Klebsiella pneumoniae / Q000201:enzymology*; D009097:Multienzyme Complexes / Q000037:antagonists & inhibitors*; D007652:Oxo-Acid-Lyases / Q000037:antagonists & inhibitors*; D010782:Photolysis
chemical_list: D000214:Acyl Coenzyme A; D000345:Affinity Labels; D001386:Azides; D009097:Multienzyme Complexes; C029890:citryl-coenzyme A; C015009:4-azidobenzoyl-coenzyme A; D004492:Edetic Acid; D007652:Oxo-Acid-Lyases; C019909:citrate (pro-3S)-lyase