title: The kinetic mechanism of inhibition of liver pyridoxal kinase with tryptophan metabolites.
abstract: The activity of purified liver pyridoxal kinase (ATP:pyridoxal 5-phosphotransferase, EC 2.7.1.35) was determined in the presence of 13 different tryptophan metabolites. Only 3-hydroxykynurenine, 3-hydroxyanthranilic acid, xanthurenic acid and quinolinic acid were found to inhibit the enzyme with I50 values of 0.1, 0.12, 0.36 and 0.42 mM, respectively. The inhibition was not related to the presence of pyridine nucleus in the metabolites molecule as was proved from the patterns of inhibition.
mesh_terms: D015095:3-Hydroxyanthranilic Acid / Q000494:pharmacology; D000818:Animals; D007700:Kinetics; D007737:Kynurenine / Q000031:analogs & derivatives; D008099:Liver / Q000201:enzymology*; D010770:Phosphotransferases / Q000037:antagonists & inhibitors*; D011731:Pyridoxal Kinase / Q000037:antagonists & inhibitors*; D011805:Quinolinic Acids / Q000494:pharmacology; D012756:Sheep; D014364:Tryptophan / Q000378:metabolism*; D014977:Xanthurenates / Q000494:pharmacology
chemical_list: D011805:Quinolinic Acids; D014977:Xanthurenates; D015095:3-Hydroxyanthranilic Acid; C005045:3-hydroxykynurenine; D007737:Kynurenine; D014364:Tryptophan; D010770:Phosphotransferases; D011731:Pyridoxal Kinase