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)

Cystathionine was cleaved into 2-ketobutyric acid, cysteine and ammonia by cystathionase. 2-Ketobutyric acid was converted into 3-ethyl-2-hydroxy-6,7-dimethoxyquinoxaline (EHDQ) by reaction with 1,2-diamino-4,5-dimethoxybenzene. When EHDQ was measured in a mobile phase of pH 2.1 using high-performance liquid chromatography with ultraviolet detection, 250 pmol of L-cystathionine in 250 microliters of the reaction mixture could be determined. Because EHDQ has a strong fluorescence in a mobile phase of pH 6.5 at 447 nm, on excitation at 365 nm, as little as 2.5 pmol of cystathionine in 250 microliters of the reaction mixture could be determined by high-performance liquid chromatography with fluorimetric detection. Cystathionase activity was assayed on the basis of the same principle by determining cystathionine in as little as 63 ng of rat liver by fluorimetric detection. Cystathionine beta-synthase activity was measured by the same method by determining cystathionine formed in only 113 ng of wet weight of rat liver. Using these methods, both cystathionine beta- and gamma-lyase activities in Saccharomyces cerevisiae were determined, because quinoxaline derivatives from pyruvate and 2-ketobutyrate could be measured simultaneously by high-performance liquid chromatography.
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PMID:Sensitive determination of cystathionine and assays for cystathionine beta- and gamma-lyase, as well as cystathionine beta-synthase, using high-performance liquid chromatography. 162 86

The contents of cystathionine and taurine, as well as cystathionine beta-synthase activity in various regions of the brains of normal and DL-propargylglycine-treated rats, were measured. The content of cystathionine in each region of brain increased gradually from 0.5 mg to 20 mg/200 g body weight in relation to the dose of DL-propargylglycine. Cystathionine was found to be unevenly distributed in brains of both normal and DL-propargylglycine-treated rats. On the other hand, the activity of cystathionine beta-synthase was evenly distributed in various regions of normal rat brain, and was unaltered following treatment of rats with DL-propargylglycine. The concentration of taurine was similarly unaffected by DL-propargylglycine injection.
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PMID:Cystathionine accumulation in various regions of brain of DL-propargylglycine-treated rats. 397 10

Cystathionine accumulated in several tissues of dams and fetuses by a single intraperitoneal administration of L-proparglyglycine to pregnant rats. Cystathionine in the liver of dams reached its maximal level at about 15 hrs after L-proparglyglycine injection (10 mg/300g), while that in the kidney and brain of dams, and in the liver, kidney, and brain of fetuses reached a maximum at about 21 hrs. The content of cystine in the liver of fetuses decreased gradually in proportion to the amount of L-proparglyglycine administered. Cystathionine gamma-lyase activity in the liver of dams and fetuses decreased to about 2-4% of that of control rats at 15 hrs after L-proparglyglycine injection, and that in the kidney and pancreas of dams to about 10-20% of that of control rats. On the other hand, cystathionine beta-synthase activity did not show significant changes from that of control rats.
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PMID:Effect of L-propargylglycine on metabolism of sulfur-containing amino acids in pregnant rats and their fetuses. 399 31

Cystathionine gamma-lyase (EC 4.4.1.1) is widely distributed in actinomycetes, e.g. genera Streptomyces, Micromonospora, Micropolyspora, Mycobacterium, Nocardia, Streptosporangium, and Streptoverticillium. The enzyme was purified from Streptomyces phaeochromogenes (IFO 3105) in nine steps. After the last steps, the enzyme appeared to be homogenous by the criteria of polyacrylamide gel electrophoresis, analytical centrifugation, and double diffusion in agarose. The enzyme crystallized in the apo form with the addition of ammonium sulfate. The enzyme has a molecular weight of about 166,000 and consists of four subunits identical in molecular weight. The enzyme exhibits absorption maxima at 278 and 421 nm and contains 4 mol of pyridoxal 5'-phosphate/mol of enzyme. L-Cystathionine, L-homoserine, DL-lanthionine, L-djenkolic acid, and L-cystine are cleaved as preferred substrates by the Streptomyces enzyme. The alpha, beta-elimination reaction of L-cystathionine is also catalyzed by the enzyme at a ratio of about one-seventh of the alpha, gamma-elimination reaction. Cystathionine beta-synthase (EC 4.2.1.22) and cystathionine gamma-synthase (EC 4.2.99.9) activities were also detected in crude extracts of S. phaeochromogenes, but cystathionine beta-lyase (EC 4.4.1.8) was not. Consequently, the reverse transsulfuration pathway in actinomycetes may be similar to that in yeast and molds.
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PMID:Cystathionine gamma-lyase of Streptomyces phaeochromogenes. The occurrence of cystathionine gamma-lyase in filamentous bacteria and its purification and characterization. 643 81

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

1. Twenty-eight male rats of initial age 27 d were fed on fortified-barley diets for 3 weeks. In all experimental diets, both crude protein (nitrogen x 6.25) and methionine:cystine were constant at 120.0 g/kg dry matter (DM) and 2:1 respectively. The basal diet contained 4.5 g methionine plus cystine/kg DM with L-methionine plus L-cystine (2:1, w/w) added in increments of 0.5 g/kg DM to a final level of 7.0 methionine plus cystine/kg DM. A 'positive-control' diet of barley plus 193.7 g soya-bean meal/kg DM contained 6.0 g methionine plus cystine/kg DM. 2. Weight gain, food conversion efficiency (FCE), urinary urea-N excretion, carcass composition and activities of liver cystathionine synthase (EC 4.2.1.22) and N5-methyltetrahydrofolate-homocysteine-methyltransferase (EC 2.1.1.13) were determined. 3. Weight gain, food consumption, FCE and carcass composition measurements of rats showed either small or no differences between the experimental diets containing 4.5--7.0 g methionine plus cystine/kg DM. For the over-all period, weight gain and FCE of rats receiving the 'positive control' diet were significantly higher than values obtained with rats receiving any of the experimental diets. 4. Cystathionine synthase activity (mumol/mg protein per 60 min; units) increased from 13.38 at 4.5 g dietary methionine plus cystine/kg DM to 18.81 at 5.0 g dietary methionine plus cystine/kg DM. The activity was then inhibited to reach a minimum value of 10.16 units at the 6.0 g/kg DM dietary level. Thereafter the activity increased to a value of 30.00 units at 7.0 g dietary methionine plus cystine/kg DM. 5. The activity of N5-methyltetrahydrofolate-methyltransferase was constant at 0.70--0.74 nmol/mg protein per 60 min between dietary levels of 4.5 and 5.0 g methionine plus cystine/kg DM. The activity then increased to a maximum value of 2.32 nmol/mg protein per 60 min at the 6.0 g/kg DM level. Thereafter the activity decreased, reaching a minimum value of 0.70 nmol/mg protein per 60 min at the 7.0 g methionine plus cystine/kg level. 6. Urinary urea-N excretion decreased significantly from 1.07 g/kg DM intake at the 4.5 g dietary methionine plus cystine/kg DM level to 1.05 g/kg DM at the 5.0 g/kg dietary level, then dropped significantly to a level of 1.01--1.00 g/kg DM intake for the higher levels of dietary methionine plus cystine.
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PMID:Growth and liver enzyme response in growing rats to graded levels of methionine plus cystine in fortified-barley diets. Response at constant methionine:cystine. 737 Feb 12

Developmental changes in the activities of cystathionine beta-synthase and cystathionine gamma-lyase were measured in six regions of rat brain. On day-1, no differences were observed in the activities of cystathionine beta-synthase and cystathionine gamma-lyase among these regions, the values being about 40 nmol/h/mg protein, and 3 nmol/h/mg protein, respectively. Cystathionine beta-synthase activity increased gradually during development at almost the same rate in each region, reaching the adult level at week-4 (about 4-fold). Cystathionine gamma-lyase activity also increased during development, reaching adult level at week-2. But, the increase of enzyme activity in the cerebellum (about 1.8-fold) was clearly lower than that in the other regions (about 4-fold). Cystathionine gamma-lyase content in the various regions of week-3 rat brain estimated by immunoblotting was consistent with the enzyme activity, and the enzyme level in the cerebellum was lower than that in the other regions. Cystathionine content of cerebellum in week-3 increased rapidly during development, and was about five-fold more than that on day-1. However, cystathionine content in the other regions did not change during development. These findings indicated that at least one reason of the high content of cystathionine in the 3 weeks rat cerebellum was due to the low level of cystathionine gamma-lyase.
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PMID:Changes in cystathionine gamma-lyase in various regions of rat brain during development. 749 71

Homocysteine can be methylated to form methionine by the cobalamin- (Cbl) and folate-dependent enzyme, methionine synthase; serum levels of total homocysteine are elevated in greater than 95% of patients with either Cbl or folate deficiency. Homocysteine can also condense with serine to form cystathionine in a pyridoxal phosphate-dependent reaction catalyzed by cystathionine beta-synthase. Cystathionine is subsequently cleaved to cysteine and alpha-ketobutyrate by the pyridoxal phosphate-dependent enzyme gamma-cystathionase. To assess levels of cystathionine in Cbl and folate deficiency, we developed a new capillary gas chromatographic-mass spectrometric assay and measured cystathionine in the serum of normal subjects and patients with clinically confirmed deficiencies of these vitamins. The normal range for serum cystathionine was 65 to 301 nmol/L (median = 126 nmol/L) for 50 normal blood donors. In 30 patients with clinically confirmed Cbl deficiency, values for cystathionine ranged from 208 nmol/L to 2,920 nmol/L (median = 816 nmol/L) and 26 (87%) had levels above the normal range. In 20 patients with clinically confirmed folate deficiency, cystathionine concentrations ranged from 138 nmol/L to 4,150 nmol/L (median = 1,560 nmol/L) and 19 (95%) had values above the normal range. Five homozygotes for cystathionine beta-synthase deficiency had high values for serum-total homocysteine and low or low-normal values for serum cystathionine that ranged from 30 nmol/L to 114 nmol/L even though they were on treatment with pyridoxine and had partially responded. One patient with a defect in the synthesis of 5-CH3-tetrahydrofolate and five patients with defects in the synthesis of CH3-Cbl had high values for serum-total homocysteine and high values for cystathionine that ranged from 311 nmol/L to 1,500 nmol/L even though they were on treatment with folic acid and Cbl, respectively, and had partially responded. We conclude that levels of cystathionine are evaluated in the serum of most patients with Cbl and folate deficiency and that they are useful in the differential diagnosis of an elevated serum-total homocysteine level.
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PMID:Elevation of serum cystathionine levels in patients with cobalamin and folate deficiency. 850 76

Epidemiological studies have provided strong evidence that an elevated plasma homocysteine concentration is an important independent risk factor for cardiovascular disease. We have shown, in the rat, that the kidney is a major site for the removal and subsequent metabolism of plasma homocysteine [Bostom, Brosnan, Hall, Nadeau and Selhub (1995) Atherosclerosis 116, 59-62]. To characterize the role of the kidney in homocysteine metabolism further, we measured the disappearance of homocysteine in isolated renal cortical tubules of the rat. Renal tubules metabolized homocysteine primarily through the transulphuration pathway, producing cystathionine and cysteine (78% of homocysteine disappearance). Methionine production accounted for less than 2% of the disappearance of homocysteine. Cystathionine, and subsequently cysteine, production rates, as well as the rate of disappearance of homocysteine, were sensitive to the level of serine in the incubation medium, as increased serine concentrations permitted higher rates of cystathionine and cysteine production. On the basis of enrichment profiles of cystathionine beta-synthase and cystathionine gamma-lyase, in comparison with marker enzymes of known location, we concluded that cystathionine beta-synthase was enriched in the outer cortex, specifically in cells of the proximal convoluted tubule. Cystathionine gamma-lyase exhibited higher enrichment patterns in the inner cortex and outer medulla, with strong evidence of an enrichment in cells of the proximal straight tubule. These studies indicate that factors that influence the transulphuration of homocysteine may influence the renal clearance of this amino acid.
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PMID:Characterization of homocysteine metabolism in the rat kidney. 935 66

The enzymatic degradation of amino acids in cheese is believed to generate aroma compounds and therefore to be essential for flavor development. Cystathionine beta-lyase (CBL) can convert cystathionine to homocysteine but is also able to catalyze an alpha, gamma elimination. With methionine as a substrate, it produces volatile sulfur compounds which are important for flavor formation in Gouda cheese. The metC gene, which encodes CBL, was cloned from the Lactococcus lactis model strain MG1363 and from strain B78, isolated from a cheese starter culture and known to have a high capacity to produce volatile compounds. The metC gene was found to be cotranscribed with a downstream cysK gene, which encodes a putative cysteine synthase. The MetC proteins of both strains were overproduced in strain MG1363 with the NICE (nisin-controlled expression) system, resulting in a >25-fold increase in cystathionine lyase activity. A disruption of the metC gene was achieved in strain MG1363. Determination of enzymatic activities in the overproducing and knockout strains revealed that MetC is essential for the degradation of cystathionine but that at least one lyase other than CBL contributes to methionine degradation via alpha, gamma elimination to form volatile aroma compounds.
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PMID:Molecular and functional analyses of the metC gene of Lactococcus lactis, encoding cystathionine beta-lyase. 1061 1


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