cystathionase


cys·ta·thi·o·nine γ-ly·ase

(sis'tă-thī'ō-nēn lī'ās), A liver enzyme, requiring pyridoxal phosphate as coenzyme, which catalyzes the hydrolysis of l-cystathionine to l-cysteine and 2-ketobutyrate, releasing NH3; also catalyzes formation of 2-ketobutyrate from l-homoserine, of pyruvate (and NH3 and H2S) from l-cysteine, and of thiocysteine, pyruvate, and NH3 from cystine. A deficiency of this enzyme results in cystathioninuria. It catalyzes a step in methionine catabolism and in cysteine biosynthesis.
See also: cystathionine β-lyase. Synonym(s): cystathionase, cysteine desulfhydrase, cystine desulfhydrase, γ-cystathionase, homoserine deaminase, homoserine dehydratase

cystathionase

(1) Cystathionine gamma-lyase, EC 4.4.1.1 (l-Cystathionine cysteine-lyase (deaminating))
(2) Cystathionine beta-lyase, EC 4.4.1.8 (cystathionine l-homocysteine-lyase (deaminating)).