title: Hydroxykynureninase and the excretion of 3-hydroxyanthranilate by yeast.
abstract: A comparative analysis of the kynureninase-type activity found in various organisms has demonstrated two forms of enzyme. One, inducible by tryptophan, has a relatively low Km for L-kynurenine, and is found in microorganisms such as Pseudomonas fluorescens and Neurospora crassa. The other, unaffected by tryptophan, has a low Km for L-3-hydroxykynurenine and is found in a wide variety of organisms, including molds, amphibia, birds and mammals. The yeast Saccharomyces cerevisiae lacks the inducible kynureninase but contains the constitutive enzyme termed an hydroxykynureninase. As a result, the yeast, unlike M. crassa, excretes 3-hydroxyanthranilate in response to L-tryptophan. However, initial studies indicate that little if any 3-hydroxyanthranilate accumulates in beer, wine or bread. Although 3-hydroxyanthranilate is suspect as an endogenous carcinogen, its carcinogenicity as an exogenous agent has not been shown.
mesh_terms: D015095:3-Hydroxyanthranilic Acid / Q000378:metabolism*; D005658:Fungi / Q000378:metabolism*; D006867:Hydrolases / Q000378:metabolism*; D007737:Kynurenine; D013045:Species Specificity; D062367:ortho-Aminobenzoates / Q000378:metabolism*
chemical_list: D062367:ortho-Aminobenzoates; D015095:3-Hydroxyanthranilic Acid; D007737:Kynurenine; D006867:Hydrolases