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Haruo Ohmori - One of the best experts on this subject based on the ideXlab platform.
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nucleotide sequence of the escherichia coli sola gene encoding a sarcosine oxidase like protein and characterization of its product
Gene, 1996Co-Authors: Yasuji Koyama, Haruo OhmoriAbstract:Abstract An Escherichia coli gene, designated solA, was identified between pyrC and htrB around 24.2 min of the genetic map. The solA gene product (SolA, 372 aa) shows strong similarities (at most 42% identities over the entire length) to monomeric sarcosine (N-methylglycine) oxidases from other bacteria. However, only low levels of sarcosine oxidase activity were detected, even when So1A was overproduced. The So1A extracts exhibited much higher (about 200-fold) reactivity toward N-methyltryptophan than toward sarcosine. Thus, So1A appears to have a substrate specificity distinct from that of monomeric sarcosine oxidases, in spite of the strong similarities in the primary structure with such enzymes.
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nucleotide sequence of the escherichia coli sola gene encoding a sarcosine oxidase like protein and characterization of its product
Gene, 1996Co-Authors: Yasuji Koyama, Haruo OhmoriAbstract:Abstract An Escherichia coli gene, designated solA, was identified between pyrC and htrB around 24.2 min of the genetic map. The solA gene product (SolA, 372 aa) shows strong similarities (at most 42% identities over the entire length) to monomeric sarcosine (N-methylglycine) oxidases from other bacteria. However, only low levels of sarcosine oxidase activity were detected, even when So1A was overproduced. The So1A extracts exhibited much higher (about 200-fold) reactivity toward N-methyltryptophan than toward sarcosine. Thus, So1A appears to have a substrate specificity distinct from that of monomeric sarcosine oxidases, in spite of the strong similarities in the primary structure with such enzymes.
M D Threadgill - One of the best experts on this subject based on the ideXlab platform.
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A biodegradable multiblock co-polymer derived from an alpha, omega-bis(methylamino)peptide and an alpha, omega-bis(oxiranylmethyl)poly(ethylene glycol).
Journal of controlled release : official journal of the Controlled Release Society, 2000Co-Authors: S E Matthews1, C W Pouton, M D ThreadgillAbstract:A novel peptide containing the lysosomally degradable sequence GlyPheLeuGly and a sequence-inverting unit has been prepared. This peptide presents the methylamino groups of sarcosine (N-methylglycine) at both termini for co-polymerisation with alpha, omega-bis(oxiranylmethoxy)poly(ethylene glycol) of mean M(w) 1650. Gel permeation chromatographic analysis showed the presence of a mixture of oligomers. Preliminary degradation studies showed that these oligomers are cleaved by cathepsin B, an important lysosomal enzyme.
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A biodegradable multiblock co-polymer derived from an α,ω-bis(methylamino)peptide and an α,ω-bis(oxiranylmethyl)poly(ethylene glycol)
Journal of Controlled Release, 2000Co-Authors: Susan E. Matthews, C W Pouton, M D ThreadgillAbstract:A novel peptide containing the lysosomally degradable sequence GlyPheLeuGly and a sequence-inverting unit has been prepared. This peptide presents the methylamino groups of sarcosine (N-methylglycine) at both termini for co-polymerisation with alpha,omega-bis(oxiranylmethoxy)poly(ethylene glycol) of mean M-w 1650. Gel permeation chromatographic analysis showed the presence of a mixture of oligomers. preliminary degradation studies showed that these oligomers are cleaved by cathepsin B, an important lysosomal enzyme. (C) 2000 Elsevier Science B.V. All rights reserved.
Tilman Sauerbruch - One of the best experts on this subject based on the ideXlab platform.
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Is the increase in serum cystathionine levels in patients with liver cirrhosis a consequence of impaired homocysteine transsulfuration at the level of gamma-cystathionase?
Scandinavian Journal of Gastroenterology, 2000Co-Authors: Maxime P Look, R Riezler, K.a. Brensing, Sally P. Stabler, Ulrich Spengler, Heiner K. Berthold, Jürgen Kurt Rockstroh, Christoph Reichel, Tilman SauerbruchAbstract:BACKGROUND: It has been suggested that the major metabolic block in the methionine catabolic pathway in cirrhotics exists at the level of the enzyme S-adenosylmethionine synthetase because in previous studies using conventional amino-acid analyzers, no intermediates of transmethylation/transsulfuration were found to accumulate in plasma downstream of S-adenosylmethionine synthesis. We therefore measured serum concentration intermediates of methionine transmethylation/transsulfuration using an improved gas chromatography/mass spectrometry technique. METHODS: Serum concentrations of methionine, homocysteine, cystathionine, N,N-dimethylglycine, N-methylglycine, methylmalonic acid, 2-methylcitric acid and alpha-aminobutyric acid were determined by gas chromatography/mass spectrometry in 108 consecutive patients with liver cirrhosis at Child stages A (mild cirrhosis, n = 27) and B/C (severe cirrhosis, n = 81), 18 outpatients with non-cirrhotic liver disease, and 55 healthy individuals. RESULTS: Serum levels of methionine, N,N-dimethylglycine, N-methylglycine, cystathionine, and homocysteine were significantly higher in patients at Child stages B/C compared with those of healthy controls (P or = 1.4 mg/dl than in patients with normal creatinine values (P < 0.01). However, the differences between cirrhotics and healthy controls were still significant after correcting for creatinine. CONCLUSIONS: Our data provides indirect evidence for two hitherto unrecognized alterations of methionine metabolism in cirrhotics, i.e. impairment of the transsulfuration of homocysteine at the level of cystathionine degradation and a shift in remethylation of homocysteine towards the betaine-homocysteine-methyltransferase reaction.
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Is the increase in serum cystathionine levels in patients with liver cirrhosis a consequence of impaired homocysteine transsulfuration at the level of gamma-cystathionase?
Scandinavian journal of gastroenterology, 2000Co-Authors: Maxime P Look, R Riezler, K.a. Brensing, Sally P. Stabler, Ulrich Spengler, Heiner K. Berthold, Jürgen Kurt Rockstroh, Christoph Reichel, Tilman SauerbruchAbstract:Background: It has been suggested that the major metabolic block in the methionine catabolic pathway in cirrhotics exists at the level of the enzyme S-adenosylmethionine synthetase because in previous studies using conventional amino-acid analyzers, no intermediates of transmethylation/transsulfuration were found to accumulate in plasma downstream of S-adenosylmethionine synthesis. We therefore measured serum concentration intermediates of methionine transmethylation/transsulfuration using an improved gas chromatography/mass spectrometry technique. Methods: Serum concentrations of methionine, homocysteine, cystathionine, N,N-dimethylglycine, N-methylglycine, methylmalonic acid, 2-methylcitric acid and α-aminobutyric acid were determined by gas chromatography/mass spectrometry in 108 consecutive patients with liver cirrhosis at Child stages A (mild cirrhosis, n = 27) and B/C (severe cirrhosis, n = 81), 18 outpatients with non-cirrhotic liver disease, and 55 healthy individuals. Results: Serum levels of methionine, N,N-dimethylglycine, N-methylglycine, cystathionine, and homocysteine were significantly higher in patients at Child stages B/C compared with those of healthy controls (P < 0.01), and they were also significantly higher than in patients with non-cirrhotic liver disease (P < 0.01 and P < 0.05 for homocysteine, respectively). They also correlated with the Child-Pugh score (P < 0.01). Homocysteine, cystathionine, N,N-dimethylglycine, N-methylglycine, methylmalonic acid, and 2-methylcitric acid correlated with serum creatinine. The mean cystathionine concentration was significantly higher in patients with creatinine ≥1.4 mg/dl than in patients with normal creatinine values (P < 0.01). However, the differences between cirrhotics and healthy controls were still significant after correcting for creatinine. Conclusions: Our data provides indirect evidence for two hitherto unrecognized alterations of methionine metabolism in cirrhotics, i.e. impairment of the transsulfuration of homocysteine at the level of cystathionine degradation and a shift in remethylation of homocysteine towards the betaine-homocysteine-methyltransferase reaction.
Yasuji Koyama - One of the best experts on this subject based on the ideXlab platform.
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nucleotide sequence of the escherichia coli sola gene encoding a sarcosine oxidase like protein and characterization of its product
Gene, 1996Co-Authors: Yasuji Koyama, Haruo OhmoriAbstract:Abstract An Escherichia coli gene, designated solA, was identified between pyrC and htrB around 24.2 min of the genetic map. The solA gene product (SolA, 372 aa) shows strong similarities (at most 42% identities over the entire length) to monomeric sarcosine (N-methylglycine) oxidases from other bacteria. However, only low levels of sarcosine oxidase activity were detected, even when So1A was overproduced. The So1A extracts exhibited much higher (about 200-fold) reactivity toward N-methyltryptophan than toward sarcosine. Thus, So1A appears to have a substrate specificity distinct from that of monomeric sarcosine oxidases, in spite of the strong similarities in the primary structure with such enzymes.
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nucleotide sequence of the escherichia coli sola gene encoding a sarcosine oxidase like protein and characterization of its product
Gene, 1996Co-Authors: Yasuji Koyama, Haruo OhmoriAbstract:Abstract An Escherichia coli gene, designated solA, was identified between pyrC and htrB around 24.2 min of the genetic map. The solA gene product (SolA, 372 aa) shows strong similarities (at most 42% identities over the entire length) to monomeric sarcosine (N-methylglycine) oxidases from other bacteria. However, only low levels of sarcosine oxidase activity were detected, even when So1A was overproduced. The So1A extracts exhibited much higher (about 200-fold) reactivity toward N-methyltryptophan than toward sarcosine. Thus, So1A appears to have a substrate specificity distinct from that of monomeric sarcosine oxidases, in spite of the strong similarities in the primary structure with such enzymes.
Sally P. Stabler - One of the best experts on this subject based on the ideXlab platform.
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Is the increase in serum cystathionine levels in patients with liver cirrhosis a consequence of impaired homocysteine transsulfuration at the level of gamma-cystathionase?
Scandinavian Journal of Gastroenterology, 2000Co-Authors: Maxime P Look, R Riezler, K.a. Brensing, Sally P. Stabler, Ulrich Spengler, Heiner K. Berthold, Jürgen Kurt Rockstroh, Christoph Reichel, Tilman SauerbruchAbstract:BACKGROUND: It has been suggested that the major metabolic block in the methionine catabolic pathway in cirrhotics exists at the level of the enzyme S-adenosylmethionine synthetase because in previous studies using conventional amino-acid analyzers, no intermediates of transmethylation/transsulfuration were found to accumulate in plasma downstream of S-adenosylmethionine synthesis. We therefore measured serum concentration intermediates of methionine transmethylation/transsulfuration using an improved gas chromatography/mass spectrometry technique. METHODS: Serum concentrations of methionine, homocysteine, cystathionine, N,N-dimethylglycine, N-methylglycine, methylmalonic acid, 2-methylcitric acid and alpha-aminobutyric acid were determined by gas chromatography/mass spectrometry in 108 consecutive patients with liver cirrhosis at Child stages A (mild cirrhosis, n = 27) and B/C (severe cirrhosis, n = 81), 18 outpatients with non-cirrhotic liver disease, and 55 healthy individuals. RESULTS: Serum levels of methionine, N,N-dimethylglycine, N-methylglycine, cystathionine, and homocysteine were significantly higher in patients at Child stages B/C compared with those of healthy controls (P or = 1.4 mg/dl than in patients with normal creatinine values (P < 0.01). However, the differences between cirrhotics and healthy controls were still significant after correcting for creatinine. CONCLUSIONS: Our data provides indirect evidence for two hitherto unrecognized alterations of methionine metabolism in cirrhotics, i.e. impairment of the transsulfuration of homocysteine at the level of cystathionine degradation and a shift in remethylation of homocysteine towards the betaine-homocysteine-methyltransferase reaction.
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Is the increase in serum cystathionine levels in patients with liver cirrhosis a consequence of impaired homocysteine transsulfuration at the level of gamma-cystathionase?
Scandinavian journal of gastroenterology, 2000Co-Authors: Maxime P Look, R Riezler, K.a. Brensing, Sally P. Stabler, Ulrich Spengler, Heiner K. Berthold, Jürgen Kurt Rockstroh, Christoph Reichel, Tilman SauerbruchAbstract:Background: It has been suggested that the major metabolic block in the methionine catabolic pathway in cirrhotics exists at the level of the enzyme S-adenosylmethionine synthetase because in previous studies using conventional amino-acid analyzers, no intermediates of transmethylation/transsulfuration were found to accumulate in plasma downstream of S-adenosylmethionine synthesis. We therefore measured serum concentration intermediates of methionine transmethylation/transsulfuration using an improved gas chromatography/mass spectrometry technique. Methods: Serum concentrations of methionine, homocysteine, cystathionine, N,N-dimethylglycine, N-methylglycine, methylmalonic acid, 2-methylcitric acid and α-aminobutyric acid were determined by gas chromatography/mass spectrometry in 108 consecutive patients with liver cirrhosis at Child stages A (mild cirrhosis, n = 27) and B/C (severe cirrhosis, n = 81), 18 outpatients with non-cirrhotic liver disease, and 55 healthy individuals. Results: Serum levels of methionine, N,N-dimethylglycine, N-methylglycine, cystathionine, and homocysteine were significantly higher in patients at Child stages B/C compared with those of healthy controls (P < 0.01), and they were also significantly higher than in patients with non-cirrhotic liver disease (P < 0.01 and P < 0.05 for homocysteine, respectively). They also correlated with the Child-Pugh score (P < 0.01). Homocysteine, cystathionine, N,N-dimethylglycine, N-methylglycine, methylmalonic acid, and 2-methylcitric acid correlated with serum creatinine. The mean cystathionine concentration was significantly higher in patients with creatinine ≥1.4 mg/dl than in patients with normal creatinine values (P < 0.01). However, the differences between cirrhotics and healthy controls were still significant after correcting for creatinine. Conclusions: Our data provides indirect evidence for two hitherto unrecognized alterations of methionine metabolism in cirrhotics, i.e. impairment of the transsulfuration of homocysteine at the level of cystathionine degradation and a shift in remethylation of homocysteine towards the betaine-homocysteine-methyltransferase reaction.
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Regulation of methionine metabolism: Effects of nitrous oxide and excess dietary methionine☆
The Journal of Nutritional Biochemistry, 1994Co-Authors: Michael S. Frontiera, Sally P. Stabler, J.fred Kolhouse, Robert H AllenAbstract:Methionine is an essential amino acid that is also converted to S-adenosylmethionine, which is used by methyltransferases that methylate DNA, RNA, protein, lipid, etc., and form S-adenosylhomocysteine that is hydrolyzed to adenosine and homocysteine. When methionine is present in excess, glycine n-methyltransferase and cystathionine beta-synthase are thought to play important regulatory roles, with the former using the excess CH3-moiety to convert glycine to n-methylglycine, and the latter condensing homocysteine with serine to form cystathionine, which is cleaved by gamma-cystathionase to cysteine and alpha-ketobutyrate. When methionine is present in low amounts, the activities of the two regulatory enzymes are thought to decrease with the homocysteine being recycled to methionine by the cobalamin-dependent enzyme methionine synthase, which simultaneously converts 5-CH3-tetrahydrofolate to tetrahydrofolate. To test this model, we fed a large dose of l-methionine to normal subjects. Using newly developed assays, we observed the following increases in serum levels: methionine, 25 fold; n-methylglycine, fourfold; homocysteine, threefold; cystathionine, 15 fold; and cysteine, unchanged. When leukemia patients were treated for 4 days with 35% nitrous oxide, which markedly inhibits methionine synthase, methionine decreased 80% by day 1 and then either stabilized or returned to normal during days 2 through 4. n-methylglycine fell 50 to 70%, and homocysteine increased 14 fold, but cystathionine increased twofold after an initial decrease or stabilization. Cysteine fell 50% by day 1 and then moved in parallel with methionine. Except for the latter increase in cystathionine, all the data support the current model of methionine regulation and demonstrate that methionine homeostasis is maintained or at least stabilized, even under conditions of extreme excess or deprivation. The unexpected increase in cystathionine levels during nitrous oxide administration is similar to what has been observed in cobalamin and folate deficiency, although the mechanism and physiologic importance remain to be determined.
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serum betaine n n dimethylglycine and n methylglycine levels in patients with cobalamin and folate deficiency and related inborn errors of metabolism
Metabolism-clinical and Experimental, 1993Co-Authors: Robert H Allen, Sally P. Stabler, John LindenbaumAbstract:Abstract Homocysteine and 5-CH 3 -tetrahydrofolate (5-CH 3 -THF) are converted to methionine and THF by the CH 3 -cobalamin (CH 3 -Cbl)-dependent enzyme methionine synthase. Serum homocysteine levels are elevated in more than 95% of patients with Cbl or folate deficiency and in patients with inborn errors involving the synthesis of 5-CH 3 -THF or CH 3 -Cbl. Homocysteine and betaine are converted to methionine and N,N -dimethylglycine by betaine-homocysteine methyltransferase. It requires neither Cbl nor folate, although N,N -dimethylglycine is converted to N -methylglycine and then to glycine in reactions that both involve the formation of 5,10-CH 2 -THF from THF. Large amounts of betaine are often given orally to patients with inborn errors, even though little is known about its metabolism in normal subjects or these patients. Thus we developed new gas chromatographic-mass spectrometric assays for serum betaine, N,N -dimethylglycine, and N -methylglycine. In 60 blood donors, we found ranges for normal serum of 17.6 to 73.3, 1.42 to 5.27, and 0.60 to 2.67 μmol/L for the three metabolites, respectively, which were normal in the majority of 50 patients with Cbl deficiency, none of whom had increased levels of N -methylglycine. In 25 patients with folate deficiency, serum betaine level was normal in most, but 76% and 60% had elevations of N,N -dimethylglycine and N -methylglycine levels that ranged as high as 343 and 43.2 μmol/L, respectively. All of seven patients on betaine therapy for inborn errors had high values for betaine (167 to 3,900 μmol/L), N,N -dimethylglycine (15.1 to 250 μmol/L), and N -methylglycine (2.93 to 49.3 μmol/L). Serum total homocysteine levels remained very high at 47.2 to 156 μmol/L (normal, 5.4 to 16.2). In patients with cbl C and cbl D mutations, methionine levels remained low or low-normal at 8.3 to 15.6 μmol/L (normal, 13.3 to 42.7) despite betaine treatment. We conclude that (1) betaine levels are maintained in most patients with Cbl and folate deficiency; (2) levels of N,N -dimethylglycine and N -methylglycine are increased in most patients with folate deficiency; and (3) betaine therapy is relatively ineffective in patients with defective synthesis of CH 3 -Cbl.
