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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
24
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pubmed:dateCreated |
1990-9-27
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pubmed:abstractText |
The combined activities of rabbit liver cytosolic serine hydroxymethyltransferase and C1-tetrahydrofolate synthase convert tetrahydrofolate and formate to 5-formyltetrahydrofolate. In this reaction C1-tetrahydrofolate synthase converts tetrahydrofolate and formate to 5,10-methenyltetrahydrofolate, which is hydrolyzed to 5-formyltetrahydrofolate by a serine hydroxymethyltransferase-glycine complex. Serine hydroxymethyltransferase, in the presence of glycine, catalyzes the conversion of chemically synthesized 5,10-methenyltetrahydrofolate to 5-formyltetrahydrofolate with biphasic kinetics. There is a rapid burst of product that has a half-life of formation of 0.4 s followed by a slower phase with a completion time of about 1 h. The substrate for the burst phase of the reaction was shown not to be 5,10-methenyltetrahydrofolate but rather a one-carbon derivative of tetrahydrofolate which exists in the presence of 5,10-methenyltetrahydrofolate. This derivative is stable at pH 7 and is not an intermediate in the hydrolysis of 5,10-methenyltetrahydrofolate to 10-formyltetrahydrofolate by C1-tetrahydrofolate synthase. Cytosolic serine hydroxymethyltransferase catalyzes the hydrolysis of 5,10-methenyltetrahydrofolate pentaglutamate to 5-formyltetrahydrofolate pentaglutamate 15-fold faster than the hydrolysis of the monoglutamate derivative. The pentaglutamate derivative of 5-formyltetrahydrofolate binds tightly to serine hydroxymethyltransferase and dissociates slowly with a half-life of 16 s. Both rabbit liver mitochondrial and Escherichia coli serine hydroxymethyltransferase catalyze the conversion of 5,10-methenyltetrahydrofolate to 5-formyltetrahydrofolate at rates similar to those observed for the cytosolic enzyme. Evidence that this reaction accounts for the in vivo presence of 5-formyltetrahydrofolate is suggested by the observation that mutant strains of E. coli, which lack serine hydroxymethyltransferase activity, do not contain 5-formyltetrahydrofolate, but both these cells, containing an overproducing plasmid of serine hydroxymethyltransferase, and wild-type cells do have measurable amounts of this form of the coenzyme.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical |
http://linkedlifedata.com/resource/pubmed/chemical/5,10-methenyltetrahydrofolate,
http://linkedlifedata.com/resource/pubmed/chemical/Glycine Hydroxymethyltransferase,
http://linkedlifedata.com/resource/pubmed/chemical/Isoenzymes,
http://linkedlifedata.com/resource/pubmed/chemical/Leucovorin,
http://linkedlifedata.com/resource/pubmed/chemical/Tetrahydrofolates,
http://linkedlifedata.com/resource/pubmed/chemical/Transferases
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pubmed:status |
MEDLINE
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pubmed:month |
Aug
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pubmed:issn |
0021-9258
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
265
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
14227-33
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading |
pubmed-meshheading:2201683-Animals,
pubmed-meshheading:2201683-Cytosol,
pubmed-meshheading:2201683-Escherichia coli,
pubmed-meshheading:2201683-Glycine Hydroxymethyltransferase,
pubmed-meshheading:2201683-Hydrolysis,
pubmed-meshheading:2201683-Isoenzymes,
pubmed-meshheading:2201683-Kinetics,
pubmed-meshheading:2201683-Leucovorin,
pubmed-meshheading:2201683-Liver,
pubmed-meshheading:2201683-Mitochondria, Liver,
pubmed-meshheading:2201683-Models, Biological,
pubmed-meshheading:2201683-Rabbits,
pubmed-meshheading:2201683-Spectrophotometry,
pubmed-meshheading:2201683-Tetrahydrofolates,
pubmed-meshheading:2201683-Transferases
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pubmed:year |
1990
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pubmed:articleTitle |
Serine hydroxymethyltransferase catalyzes the hydrolysis of 5,10-methenyltetrahydrofolate to 5-formyltetrahydrofolate.
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pubmed:affiliation |
Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Medical College of Virginia, Richmond 23298.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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