title: Kynurenine pathway enzymes in guinea pigs.
abstract: In some animals, the administration of repeated doses of tryptophan can cause death. It has been reported that guinea pig does not survive repeated doses of tryptophan, due to the absence of the hormonal induction mechanism of liver tryptophan 2,3-dioxygenase (TDO). Therefore, it was of interest to investigate if guinea pig is an animal model suitable for studying tryptophan metabolism. The activities of the enzymes of the kynurenine pathway were determined. Liver TDO was present only as a holoenzyme; kynurenine 3-monooxygenase showed similar, but very high, activity in both liver and kidney. Liver and kidney kynureninase values were also similar, whereas kynurenine-oxoglutarate transaminase activity was higher in kidney than in liver. 3-Hydroxyanthranilate 3,4-dioxygenase gave similar, but very high, values in both liver and kidney, whereas aminocarboxymuconate-semialdehyde decarboxylase activity was double in kidney with respect to liver, but much lower than that of 3-hydroxyanthranilate 3,4-dioxygenase. Total and free tryptophan concentrations in serum were also determined. The free fraction was about 10% of total tryptophan.
authors.affiliation: Department of Pharmaceutical Sciences, University of Padova, Via Marzolo 5, I-35131 Padova, Italy. graziella.allegri@unipd.it
authors.forename: Graziella
authors.initials: G
authors.lastname: Allegri
authors.forename: Carlo V L
authors.initials: CV
authors.lastname: Costa
authors.forename: Eugenio
authors.initials: E
authors.lastname: Ragazzi
authors.forename: Antonella
authors.initials: A
authors.lastname: Bertazzo
authors.forename: Monica
authors.initials: M
authors.lastname: Biasiolo
mesh_terms: D000818:Animals; D005260:Female; D006168:Guinea Pigs; D007421:Intestine, Small / Q000201:enzymology; D007668:Kidney / Q000201:enzymology; D007737:Kynurenine / Q000378:metabolism*; D050601:Kynurenine 3-Monooxygenase; D008099:Liver / Q000201:enzymology; D006899:Mixed Function Oxygenases / Q000378:metabolism; D013482:Superoxide Dismutase / Q000378:metabolism; D014364:Tryptophan / Q000378:metabolism; D014366:Tryptophan Oxygenase / Q000378:metabolism
chemical_list: D007737:Kynurenine; D014364:Tryptophan; D006899:Mixed Function Oxygenases; D014366:Tryptophan Oxygenase; D050601:Kynurenine 3-Monooxygenase; D013482:Superoxide Dismutase