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Predicate | Object |
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rdf:type | |
lifeskim:mentions | |
pubmed:issue |
7
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pubmed:dateCreated |
1992-3-30
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pubmed:abstractText |
Solutions of 5,10-methenyltetrahydropteroylglutamate can be converted to a stable hydrated adduct by heating solutions at 50 degrees C at pH values of 3-5 for several hours. The adduct is stable at pH values from 4 to 9 for hours, but at pH values below 2 it is converted to 5,10-methenyltetrahydropteroylglutamate and at pH values above 8 it is converted to 5-formyltetrahydropteroylglutamate. Arguments are presented that the adduct is (11R)-5,10-hydroxymethylenetetrahydropteroylglutamate formed from (11S)-5,10-hydroxymethylenetetrahydropteroylglutamate by formation of an ylide at C-11 which undergoes inversion of the electron pair to form the (11R) isomer. The (11R) hydrated adducted is believed to be the isomer of 5,10-methenyltetrahydropteroylglutamate referred to as anhydroleucovorin B by Cosulich et al. [Cosulich, D. C., Roth, B., Smith, J. M., Hultquist, M. E., & Parker, R. P. (1952) J. Am. Chem. Soc. 74, 3252-3263]. In addition, a new mechanism for the formation of 5-formyltetrahydropteroylglutamate from either 5,10-methenyltetrahydropteroylglutamate or 10-formyltetrahydropteroylglutamate via (11R)-5,10-hydroxymethylenetetrahydropteroylglutamate is proposed. A requirement for this pathway is that the formyl proton of 10-formyltetrahydropteroylglutamate exchange with solvent protons. The exchange of this formyl proton was observed at all pH values from 5.5 to 11.5 at a rate which exceeded by more than an order of magnitude the rate of formation of 5-formyltetrahydropteroylglutamate.
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pubmed:grant | |
pubmed:language |
eng
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pubmed:journal | |
pubmed:citationSubset |
IM
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pubmed:chemical | |
pubmed:status |
MEDLINE
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pubmed:month |
Feb
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pubmed:issn |
0006-2960
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pubmed:author | |
pubmed:issnType |
Print
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pubmed:day |
25
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pubmed:volume |
31
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pubmed:owner |
NLM
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pubmed:authorsComplete |
Y
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pubmed:pagination |
2148-55
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pubmed:dateRevised |
2007-11-14
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pubmed:meshHeading | |
pubmed:year |
1992
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pubmed:articleTitle |
Evidence for the accumulation of a stable intermediate in the nonenzymatic hydrolysis of 5,10-methenyltetrahydropteroylglutamate to 5-formyltetrahydropteroylglutamate.
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pubmed:affiliation |
Department of Biochemistry and Molecular Biophysics, Virginia Commonwealth University, Richmond 23298.
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pubmed:publicationType |
Journal Article,
Research Support, U.S. Gov't, P.H.S.
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