Cystathionine


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Cystathionine

 

(also 2,7-diamino-4-thiasuberic acid), HOOCCH(NH2)CH2CH2SCH2CH(NH2)COOH, an amino acid containing a sulfide group. Cystathionine is an important intermediate in the biosynthesis and metabolism of amino acids containing sulfur. Of the four optically active and two racemic forms of the acid, only L-cystathionine and L-allo-cystathionine are biologically active. In mammals, L-cystathionine participates in the biosynthesis of cysteine from methionine and serine; in plants and bacteria, it participates in the biosynthesis of methionine from cysteine and homoserine.

References in periodicals archive ?
Vitamin B-6 deficiency in rats reduces hepatic serine hydroxymethyltransferase and cystathionine [beta]-synthase activities and rates of in vivo protein turnover, homocysteine remethylation and transsulfuration.
The most common cause of severe inherited hyperhomocysteinemia is cystathionine [beta]-synthase deficiency (classical homocystinuria, type I), which has a prevalence of between 1 in 200 000 and 1 in 335 000 (4).
Homozygous cystathionine [beta]-synthase deficiency, combined with factor V Leiden or thermolabile methylenetetrahydrofolate reductase in the risk of venous thrombosis.
Cystathionine in the urine meant that the patient did not have the first disease, homocystinuria; in other words, there was a different enzyme defect in this little baby.
Is the increase in serum cystathionine levels in patients with liver cirrhosis a consequence of impaired homocysteine transsulfuration at the level of gamma-cystathionase?
While discussing the differential diagnosis of hyperhomocysteinemia, the authors mentioned that cystathionine [beta]-synthase deficiency was considered unlikely owing to the lack of classic clinical signs of this disease (long-bone overgrowth, lens dislocation).
The transsulfurating enzyme, cystathionine [beta]-synthase (CBS) is activated [14] and the remethylating enzyme, betane:homocysteine methyltransferase (BHMT) is inhibited by Adomet and AdoHcy (Fi.
L-cysteine is degraded in rumen by a microbial cystathionine [gamma]-lyase to generate sulphide, then, sulphur ion generated from sulphide can bind to W to form an insoluble inorganic compound.
Vitamin B6 is a coenzyme for the conversion of homocysteine to nontoxic cystathionine, and deficiency of the vitamin is associated with abnormal homocysteine metabolism.
A series of transsexual human clinical studies demonstrated that testosterone administration at least partially blocked the conversation of homocysteine to cystathionine by cystathionine [beta]synthase (CBS), whereas estrogen administration had the opposite affect (152, 153).
Pyridoxine-responsive cystathionine beta-synthase deficiency, and most homocysteine remethylation disorders are unlikely to result in significant elevations in methionine in otherwise healthy term infants at one day of age, while prematurity and hepatic dysfunction are notorious for false-positive alerts.