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MGP003754

UniProt Annotations

Entry Information
Gene Namekynureninase
Protein EntryKYNU_HUMAN
UniProt IDQ16719
SpeciesHuman
Comments
Comment typeDescription
Alternative ProductsEvent=Alternative splicing; Named isoforms=2; Name=1; IsoId=Q16719-1; Sequence=Displayed; Name=2; IsoId=Q16719-2; Sequence=VSP_042739, VSP_042740; Note=No experimental confirmation available.;
Biophysicochemical PropertiesKinetic parameters: KM=493 uM for L-kynurenine (at pH 7.0) {ECO:0000269|PubMed:11985583, ECO:0000269|PubMed:17300176, ECO:0000269|PubMed:8706755, ECO:0000269|PubMed:9180257}; KM=28.3 uM for DL-3-hydroxykynurenine (at pH 7.0) {ECO:0000269|PubMed:11985583, ECO:0000269|PubMed:17300176, ECO:0000269|PubMed:8706755, ECO:0000269|PubMed:9180257}; KM=3.0 uM for DL-3-hydroxykynurenine (at pH 7.9) {ECO:0000269|PubMed:11985583, ECO:0000269|PubMed:17300176, ECO:0000269|PubMed:8706755, ECO:0000269|PubMed:9180257}; pH dependence: Optimum pH is 8.25 with DL-3-hydroxykynurenine as substrate. {ECO:0000269|PubMed:11985583, ECO:0000269|PubMed:17300176, ECO:0000269|PubMed:8706755, ECO:0000269|PubMed:9180257};
Catalytic ActivityL-3-hydroxykynurenine + H(2)O = 3- hydroxyanthranilate + L-alanine. {ECO:0000255|HAMAP- Rule:MF_03017}.
Catalytic ActivityL-kynurenine + H(2)O = anthranilate + L- alanine. {ECO:0000255|HAMAP-Rule:MF_03017}.
CautionIt has been reported that this enzyme possesses no measurable activity against L-kynurenine and is subject to inhibition by both L-kynurenine and D-kynurenine at pH 7.9. {ECO:0000305|PubMed:11985583}.
CofactorName=pyridoxal 5'-phosphate; Xref=ChEBI:CHEBI:597326;
DiseaseNote=Xanthurenic aciduria manifesting as massive urinary excretion of large amounts of kynurenine, 3-hydroxykynurenine and xanthurenic acid has been observed in an individual carrying a homozygous missense change in KYNU (PubMed:17334708). The urinary pattern in the patient suggests kynureninase deficiency and a block in the conversion of kynurenine and 3-hydroxykynurenine to anthranilate and 3-hydroxyanthranilate, respectively. {ECO:0000269|PubMed:17334708}.
Enzyme RegulationInhibited by o-methoxybenzoylalanine (OMBA). {ECO:0000269|PubMed:8706755, ECO:0000269|PubMed:9180257}.
FunctionCatalyzes the cleavage of L-kynurenine (L-Kyn) and L-3- hydroxykynurenine (L-3OHKyn) into anthranilic acid (AA) and 3- hydroxyanthranilic acid (3-OHAA), respectively. Has a preference for the L-3-hydroxy form. Also has cysteine-conjugate-beta-lyase activity.
InductionIncreased levels in several cerebral and systemic inflammatory conditions.
Mass SpectrometryMass=52400; Method=MALDI; Range=1-465; Note=The reported mass is given to only three significant figures.; Evidence={ECO:0000269|PubMed:11985583};
PathwayAmino-acid degradation; L-kynurenine degradation; L- alanine and anthranilate from L-kynurenine: step 1/1. {ECO:0000255|HAMAP-Rule:MF_03017}.
PathwayCofactor biosynthesis; NAD(+) biosynthesis; quinolinate from L-kynurenine: step 2/3. {ECO:0000255|HAMAP-Rule:MF_03017}.
SimilarityBelongs to the kynureninase family. {ECO:0000255|HAMAP-Rule:MF_03017}.
Subcellular LocationCytoplasm {ECO:0000255|HAMAP-Rule:MF_03017, ECO:0000269|PubMed:8706755}.
SubunitHomodimer. {ECO:0000255|HAMAP-Rule:MF_03017, ECO:0000269|PubMed:17300176}.
Tissue SpecificityExpressed in all tissues tested (heart, brain placenta, lung, liver, skeletal muscle, kidney and pancreas). Highest levels found in placenta, liver and lung. Expressed in all brain regions. {ECO:0000269|PubMed:8706755, ECO:0000269|PubMed:9180257}.
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