Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:4.2.1.22 (cystathionine beta-synthase)
965 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

S-(2-Hydroxy-2-carboxyethyl)homocysteine, S-(3-hydroxy-3-carboxy-n-propyl)-cysteine, N-acylated S-(beta-carboxyethyl)cysteine, and N-acylated S-(3-hydroxy-3-carboxy-n-propyl) cysteine were excreted in the urine after DL-propargylglycine treatment. Cystathionine was also accumulated in several tissues of DL-propargylglycine-treated rats. N-Monoacetylcystathione was found in the liver of rats and was also detected in the kidney and serum. Cystathionine gamma-lyase activity in liver decreased to about 4% of that of control rats 24 h after the DL-propargylglycine injection, and alanine aminotransferase activity decreased to about 35% of that of control rats. On the other hand, aspartate aminotransferase and cystathionine beta-synthese activity did not show significant changes from those of control rats. The ability of normal tissues to synthesize cystathionine utilizing cystathionine beta-synthase was 1.98 +/- 0.40 mumol/min/g in liver, 0.61 +/- 0.13 in kidney, and 0.18 +/- 0.015 in brain. The maximal contents of cystathionine in rat tissues and the administered amounts of DL-propargylglycine agreed well with the ability to synthesize cystathionine in each tissue.
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PMID:Unusual metabolism of sulfur-containing amino acids in rats treated with DL-propargylglycine. 661 21

Precocious atherosclerosis occurs in homocystinuria due to cystathionine beta-synthase deficiency and there is evidence that homocysteine may produce endothelial damage. Mild homocysteinemia has been reported in heterozygotes after methionine loads and it has been suggested that they could have an increased risk of atherogenesis. We measured plasma amino acids before and after a methionine load (100 mg per kg) in 17 obligatory heterozygotes, in 20 men under 50 yr with established ischemic heart disease, and in matched controls, to determine whether methionine loading allows identification of heterozygotes, and whether there is an altered rate of methionine metabolism in patients with premature coronary artery disease. The obligate heterozygotes had higher mean plasma concentrations of methionine and total homocysteine at 4, 8 and 12 hours after the load than their controls, and lower concentrations of total cysteine and taurine in fasting and all post load samples; however, there was considerable overlap of measurements in heterozygotes and their controls even when differential weightings were applied. There were no differences in mean plasma concentrations of methionine, total homocysteine or total cysteine between the patients with ischemic heart disease and their controls at any measurement point. However, two patients with premature coronary artery disease, identical twins, had persistent elevation of total plasma homocysteine and an exaggerated homocysteine response to methionine. Oral folate restored homocysteine concentrations before and after methionine to normal.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Homocysteinemia, ischemic heart disease, and the carrier state for homocystinuria. 668 24

The treatment of homocystinuria that is not responsive to pyridoxine is not usually biochemically or clinically successful, and vascular, ocular, and skeletal complications commonly supervene. Persistent marked homocysteinemia appears to be the most important biochemical disturbance leading to these complications. Ten patients with cystathionine beta-synthase deficiency that was not responsive to pyridoxine and one patient with homocystinuria due to a defect in cobalamin metabolism were treated with 6 g daily of betaine added to conventional therapy, to improve homocysteine remethylation. All patients had a substantial decrease in plasma total homocysteine levels (P less than 0.001) and an increase in total cysteine levels (P less than 0.001). Changes in plasma methionine concentrations were variable. Fasting levels of plasma amino acids became normal in two patients, and in six there was immediate clinical improvement. There were no unwanted effects. We conclude that treatment of homocystinuria that is not responsive to pyridoxine and of disorders of homocysteine remethylation should include betaine in adequate doses to ensure maximum lowering of elevated plasma homocysteine levels.
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PMID:Homocystinuria--the effects of betaine in the treatment of patients not responsive to pyridoxine. 687 13

Low-molecular-weight O-acetyl-l-serine sulfhydrylase was purified from a cysteine auxotroph of Saccharomyces cerevisiae and was demonstrated to be identical with l-serine sulfhydrylase.
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PMID:Low-molecular-weight O-acetylserine sulfhydrylase and serine sulfhydrylase of Saccharomyces cerevisiae are the same protein. 702 36

In order to ascertain the role of L-serine sulfhydro-lyase (L-serine hydro-lyase (adding homocysteine) EC 4.2.1.22) which also catalyzes sulfhydrylation of O-acetyl-L-serine (Yamagata, S. (1981) J. Bacteriol. 147, 688-690), the enzyme was partially purified from a wild-type strain and three cysteine auxotrophs of Saccharomyces cerevisiae, and the molecular and enzymatic properties of these preparations were compared. The results showed no significant difference in properties investigated, indicating that cysteine synthesis is exclusively performed in this organism through sulfhydrylation of O-acetyl-L-serine, catalyzed not by serine sulfhydro-lyase but by O-acetylserine . O-acetylhomoserine sulfhydro-lyase (Yamagata, S., Takeshima, K. and Naiki, N. (1974) J. Biochem. 75, 1221-1229). Insensitivity of the former enzyme to L-methionine also supported this conclusion.
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PMID:Partial purification and comparison of some properties of L-serine sulfhydro-lyase of Saccharomyces cerevisiae. 703 82

The accumulation of homocyst(e)ine in rats deficient in vitamin B-6 was monitored. Homocysteine and cysteine linked by disulfide bonds to plasma proteins, to red blood cells (RBC) membranes, and free in plasma were analyzed by HPLC separation and electrochemical detection. As the vitamin B-6 deficiency progressed, the concentration of plasma protein-bound and RBC membrane-bound homocysteine increased and that of cysteine decreased. Changes in free homocysteine concentration paralleled those seen in protein-bound homocysteine, but free cystein concentration did not fluctuate throughout the deficiency. Refeeding vitamin B-6 to deficient animals resulted in a return of homocysteine and cysteine concentrations to control levels within 2 days. Bound homocysteine and cysteine and plasma free homocyst(e)ine concentrations in rats deficient in vitamin B-6 were in the same concentration range as those seen in patients with homocystinuria due to cystathionine beta-synthase deficiency. Monitoring changes in plasma protein-bound and free homocysteine concentration during vitamin B-6 deficiency in rats may provide a useful system for the study of cystathionine beta-synthase deficiency and its treatment.
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PMID:Accumulation of homocyst(e)ine in vitamin B-6 deficiency: a model for the study of cystathionine beta-synthase deficiency. 709 45

There is as yet no satisfactory experimental model for homocystinuria due to cystathionine beta-synthase deficiency. We produced homocysteinemia in pigs for up to 60 days by continuously infusing DL-homocysteine thiolactone and compared the changes in the plasma amino acids with the findings in 16 patients with homocystinuria. Vascular morphology was also investigated in the infused animals. In six pigs DL-homocysteine thiolactone, 0.68/kg/day for 13-60 days increased mean levels of methionine from 43.6 to 116.6 mumole/l, homocystine from zero to 67.4, cysteine-homocysteine disulfide from 4.3 to 49.2, taurine from 97.3 to 193.9 and alpha-amino-n-butyric acid from 16.5 to 147.4. Total cysteine did not change although cystine decreased from 50.8 to 26.2 mumole/liter. There were no amino acid changes in four saline infused (control) pigs and no differences in vascular morphology between experimental and control animals. Seven severely affected homocystinuric patients, biochemically, unresponsive to pyridoxine administration, had plasma sulfur-containing amino acid changes of similar magnitude to those in the infused pigs except that taurine concentrations were normal and total cysteine was decreased as it also was in nine pyridoxine responsive patients. In contrast to the pigs, plasma alpha-amino-n-butyric acid was normal in all 16 patients. We conclude that this model provides information about methionine metabolism but that it should be used with caution to study mechanisms in homocystinuria because it does not exactly mimic the human disease and because the thiolactone, which at present must be used as the source of infused L-homocysteine, itself produces changes which could influence results.
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PMID:Experimental homocysteinemia in pigs: comparison with studies in sixteen homocystinuric patients. 709 48

The contribution of cystathionine gamma-lyase, cystathionine beta-synthase and cysteine aminotransferase coupled to 3-mercaptopyruvate sulphurtransferase to cysteine desulphhydration in rat liver and kidney was assessed with four different assay systems. Cystathionine gamma-lyase and cystathionine beta-synthase were active when homogenates were incubated with 280 mM-L-cysteine and 3 mM-pyridoxal 5'-phosphate at pH 7.8. Cysteine aminotransferase in combination with 3-mercaptopyruvate sulphurtransferase catalysed essentially all of the H2S production from cysteine at pH 9.7 with 160 mM-L-cysteine, 2 mM-pyridoxal 5'-phosphate, 3 mM-2-oxoglutarate and 3 mM-dithiothreitol. At more-physiological concentrations of cysteine (2 mM) cystathionine gamma-lyase and cystathionine beta-synthase both appeared to be active in cysteine desulphhydration, whereas the aminotransferase pathway did not. The effect of inhibition of cystathionine gamma-lyase by a suicide inactivator, propargylglycine, in the intact rat was also investigated; there was no significant effect of propargylglycine administration on the urinary excretion of total 35S, 35SO4(2-) or [35S]taurine formed from labelled dietary cysteine.
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PMID:Characterization of the enzymic capacity for cysteine desulphhydration in liver and kidney of the rat. 715 Feb 44

Extracts of Desulfovibrio vulgaris were found to contain serine transacetylase and cysteine synthase activities. When extracts were incubated with bisulfite and o-acetylserine, or acetyl coenzyme A plus L-serine, under a hydrogen atmosphere, cysteine was formed. Pyruvate served as a reductant for bisulfite reduction to sulfide and concomitantly provided the acetyl moiety for acetyl coenzyme A formation. Consequently, when extracts were incubated with pyruvate, bisulfite, and L-serine, cysteine synthesis resulted.
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PMID:Cysteine synthesis by Desulfovibrio vulgaris extracts. 736 31

Hepatic cystathionine beta-synthase activity is decreased by the addition of cysteine to the diet. This effect of cysteine was slightly greater in diets containing 0.25% methionine than in those containing 1% methionine, and was reduced during aging. Similar changes were observed in the level of the mRNA of this enzyme, although the changes in the transcript levels were slightly greater than the changes in enzyme activity. Thus, we conclude that the addition of cysteine to a methionine-containing diet causes a decrease in cystathionine beta-synthase activity mainly by diminishing its mRNA level.
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PMID:Effect of cysteine on expression of cystathionine beta-synthase in the rat liver. 756 13


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