Kynureninase belongs to theclass V group ofaspartate aminotransferase superfamily of structurally homologous pyridoxal 5'-phosphate (PLP) dependent enzymes. To date, two structures of human kynureninase have determined by X-ray diffraction with resolutions of 2.0 and 1.7 Å.[1][8] Forty percent of the amino acids are arranged in an alpha helical and twelve percent are arranged in beta sheets. Docking of the kynurenine substrate into the active site suggests that Asn-333 and His-102 are involved in substrate binding.[1]
In KYNU reaction, PLP facilitates Cβ-Cγ bond cleavage. The reaction follows the same steps as thetransamination reaction but does not hydrolyze thetautomerizedSchiff base. The proposed reaction mechanism involves an attack of an enzymenucleophile on the carbonyl carbon (Cγ) of the tautomerized 3hKyn-PLP Schiff base. This is followed by Cβ-Cγ bond cleavage to generate an acyl-enzyme intermediate together with a tautomerized Ala-PLP adduct. Hydrolysis of the acyl-enzyme then yields 3hAnt.
Zhang Y, Zhang KX, He X, et al. (2005). "[A polymorphism of kynureninase gene in a hypertensive candidate chromosomal region is associated with essential hypertension]".Zhonghua Xin Xue Guan Bing Za Zhi.33 (7):588–91.PMID16080802.
Inada J, Okuno E, Kimura M, Kido R (1984). "Intracellular localization and characterization of 3-hydroxykynureninase in human liver".Int. J. Biochem.16 (6):623–8.doi:10.1016/0020-711x(84)90031-4.PMID6468727.
Ubbink JB, Vermaak WJ, Bissbort SH (1991). "High-performance liquid chromatographic assay of human lymphocyte kynureninase activity levels".J. Chromatogr.566 (2):369–75.doi:10.1016/0378-4347(91)80253-9.PMID1939450.
Maruyama K, Sugano S (1994). "Oligo-capping: a simple method to replace the cap structure of eukaryotic mRNAs with oligoribonucleotides".Gene.138 (1–2):171–4.doi:10.1016/0378-1119(94)90802-8.PMID8125298.
Christensen M, Duno M, Lund AM, et al. (2007). "Xanthurenic aciduria due to a mutation in KYNU encoding kynureninase".J. Inherit. Metab. Dis.30 (2):248–55.doi:10.1007/s10545-007-0396-2.PMID17334708.S2CID13295336.
Walsh HA, Botting NP (2002). "Purification and biochemical characterization of some of the properties of recombinant human kynureninase".Eur. J. Biochem.269 (8):2069–74.doi:10.1046/j.1432-1033.2002.02854.x.PMID11985583.
Suzuki Y, Yoshitomo-Nakagawa K, Maruyama K, et al. (1997). "Construction and characterization of a full length-enriched and a 5'-end-enriched cDNA library".Gene.200 (1–2):149–56.doi:10.1016/S0378-1119(97)00411-3.PMID9373149.
