Kynureninase

Kynureninase
	Ribbons / surface model of human kynureninase, with PLP and an inhibitor ( calottes ), according to PDB 3E9K
	Existing structural data : 2hzp
Properties of human protein
Mass / length primary structure	465 amino acids
Secondary to quaternary structure	Homodimer
Cofactor	Pyridoxal phosphate
Identifier
Gene name	KYNU
External IDs	OMIM : 605197 ; UniProt : Q16719 ;
Enzyme classification
EC, category	3.7.1.3 , hydrolase
Response type	Hydrolysis of a CC bond
Substrate	3-hydroxykynurenine + H 2 O
Products	3-hydroxyanthranilate + alanine
Occurrence
Homology family	Kynureninase
Parent taxon	Creature

In kynureninase is the one enzyme that of 3-hydroxykynurenine a molecule alanine cleaving. This reaction is a partial step in the breakdown of the amino acid tryptophan and in nicotinic acid biosynthesis. Kynureninase occurs in all living things. In humans it can be found in all tissue types, but especially in the placenta , liver and lungs . Elevated levels of the enzyme have been found near infections.

Mutations in KYNU - gene can lead to lack of kynureninase. The result is a vitamin B3 deficiency and an increased excretion of the tryptophan breakdown products kynurenine , 3-hydroxykynurenine and xanthurenic acid in the urine.

Variants of the enzyme have been linked to high blood pressure in Han Chinese.

Catalyzed reaction

Details of the reaction sequence catalyzed by kynureninase. Color scheme: KYNU , pyridoxal phosphate , substrate names , inorganic molecules , substrate , L-Ala

+ H ₂ O + ${\ displaystyle \ longrightarrow}$

L-alanine is split off from 3-hydroxy-L-kynurenine by hydrolysis and 3-hydroxyanthranilate is formed.

Web links

Wikibooks: Biochemistry and Pathobiochemistry: Tryptophan Metabolism - Learning and Teaching Materials

3-hydroxykynurenine + H2O ⇒ 3-hydroxyanthranilate + alanine . reactome.org

Individual evidence

↑ UniProt Q16719
↑ Kynureninase Deficiency. In: Online Mendelian Inheritance in Man . (English).
↑ M Christensen, M Duno, AM Lund, F Skovby, E Christensen: Xanthurenic aciduria due to a mutation in KYNU encoding kynureninase . In: J. Inherit. Metab. Dis. . 30, No. 2, April 2007, pp. 248-255. doi : 10.1007 / s10545-007-0396-2 . PMID 17334708 .
↑ Y Zhang, KX Zhang, X He et al .: [A polymorphism of kynureninase gene in a hypertensive candidate chromosomal region is associated with essential hypertension] . In: Zhonghua Xin Xue Guan Bing Za Zhi . 33, No. 7, July 2005, pp. 588-591. PMID 16080802 .

[1] UniProt Q16719

[2] Kynureninase Deficiency. In: Online Mendelian Inheritance in Man . (English).

[3] M Christensen, M Duno, AM Lund, F Skovby, E Christensen: Xanthurenic aciduria due to a mutation in KYNU encoding kynureninase . In: J. Inherit. Metab. Dis. . 30, No. 2, April 2007, pp. 248-255. doi : 10.1007 / s10545-007-0396-2 . PMID 17334708 .

[4] Y Zhang, KX Zhang, X He et al .: [A polymorphism of kynureninase gene in a hypertensive candidate chromosomal region is associated with essential hypertension] . In: Zhonghua Xin Xue Guan Bing Za Zhi . 33, No. 7, July 2005, pp. 588-591. PMID 16080802 .