Medical Term:

cystathionine γ-lyase

Pronunciation: sis′tă-thī′ō-nēn lī′ās

Definition: 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.

Synonym(s): cystathionase, cysteine desulfhydrase, cystine desulfhydrase, γ-cystathionase, homoserine deaminase, homoserine dehydratase

See Also: cystathionine β-lyase

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