Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:4.2.1.22 (cystathionine beta-synthase)
 965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Rats fed with a vitamin B6-deficient 70% casein diet for 5 weeks were found to have decreased considerably in the content of phosphatidylcholine (PC) in liver microsomes, presumably because of the depressed PC biosynthesis from choline or phosphatidylethanolamine (PE). The activities of choline phosphokinase and choline phosphotransferase in liver decreased, apparently, as compared with the pair-fed control or control rats. The hepatic level of the PE methyltransferase co-substrate, S-adenosylmethionine (SAM), decreased about 1/3, but the level of the inhibitory metabolite, S-adenosylhomocysteine (SAH), was elevated due to the marked reduction in the activities of cystathionine beta-synthase and gamma-cystathionase. The resultant molar ratio of SAM/SAH decreased drastically such that the methylation of PE to PC was decreased in vivo, as confirmed by lowering the activity of PE methyltransferase in vitro in response to a decreased molar ratio of SAM/SAH. A similar effect on the PE methylation was also observed in the pair-fed control rats, but the PC biosynthesis from choline clearly compensated for the drop of PC biosynthesis from PE. Results of this study demonstrate that vitamin B6 deficiency modified methionine metabolism and decreased choline utilization, and thus indirectly affected the biosynthesis of PC in liver microsomes.
 ...
PMID:Alteration in the phosphatidylcholine biosynthesis of rat liver microsomes caused by vitamin B6 deficiency. 776 14

The effect of concentrations of sulfur-containing amino acids, activities of cystathionine gamma-lyase and cystathionine beta-synthase, and level of vitamin B6 were examined following menthionine administration in normal rats and chronically uremic rats with 7/8 nephrectomy. In the uremic rats, the serum levels of methionine, cystathionine, cysteine and taurine increased in proportion to the amounts of methionine administered. The increase of taurine content in the serum and liver was particularly marked. Cystathionine beta-synthase activity in the liver increased with the administration, but the serum level of pyridoxal phosphate decreased markedly. The body weight gain of rats decreased with the administration, and the contents of urea and creatinine in serum increased. Thus, vitamin B6 deficiency in chronically uremic rats administered with large amounts of methionine may reduce growth, lower renal function and cause abnormal metabolism of sulfur-containing amino acids.
 ...
PMID:Content of sulfur amino acids and vitamin B6 and related enzyme activities in rats with chronic renal failure fed a high methionine diet. 888 37

Recent studies suggest that apart from nitric oxide (NO) and carbon monoxide (CO), hydrogen sulfide (H2S) is another inorganic gaseous mediator in the cardiovascular system. H2S is synthesized from L-cysteine by either cystathionine beta-synthase (CBS) or cystathionin gamma--lyase (CSE), both using pyridoxal 5'-phosphate (vitamin B6) as a cofactor. CBS is the main H2S-producing enzyme in the brain and CSE is involved in H2S formation in the cardiovascular system. H2S induces hypotension in vivo and vasodilation vitro by opening KATP channels in vascular smooth muscle cells. Chronic administration of CSE inhibitor induces arterial hypertension in the rat. In addition, decreased H2S generation has been demonstrated in the vasculature of spontaneously hypertensive rat, in experimental hypertension induced by NO synthase blockade, and in hypoxia-induced pulmonary hypertension, and administration of exogenous H2S donor has significant therapeutic effects in these models. Deficiency of H2S may contribute to atherogenesis in some patients with hyperhomocysteinemia, in whom the metabolism of homocysteine to cysteine and H2S is compromised by vitamin B6 deficiency. Reduced H2S production in the brain was observed in patients with Alzheimer's disease. On the other hand, excess of H2S may lead to mental retardation in patients with Down's syndrome and may be involved in the pathogenesis of hypotension associated with septic shock.
 ...
PMID:[Hydrogen sulfide as a biologically active mediator in the cardiovascular system]. 1528 Jul 98