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Title: Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues

Abstract

A variety of folate analogues were synthesized to explore the specificity of the folate binding site of hog liver folypolyglutamate synthetase and the requirements for catalysis. Modifications of the internal and terminal glutamate moieties of folate cause large drops in on rates and/or affinity for the protein. The only exceptions are glutamine, homocysteate, and ornithine analogues, indicating a less stringent specificity around the delta-carbon of glutamate. It is proposed that initial folate binding to the enzyme involves low-affinity interactions at a pterin and a glutamate site and that the first glutamate bound is the internal residue adjacent to the benzoyl group. Processive movement of the polyglutamate chain through the glutamate site and a possible conformational change in the protein when the terminal residue is bound would result in tight binding and would position the ..gamma..-carboxyl of the terminal glutamate in the correct position for catalysis. The 4-amino substitution of folate increases the on rate for monoglutamate derivatives but severely impairs catalysis with diglutamate derivatives. Pteroylornithine derivatives are the first potent and specific inhibitors of folylpolyglutamate synthetase to be identified and may act as analogues of reaction intermediates. Other folate derivatives with tetrahedral chemistry replacing the peptide bond, such as pteroyl-..gamma..-glutamyl-(psi,CH/submore » 2/-NH)-glutamate, retain affinity for the protein but are considerably less effective inhibitors than the ornithine derivatives. Enzyme activity was assayed using (/sup 14/C)glutamate.« less

Authors:
; ;
Publication Date:
Research Org.:
Johns Hopkins Univ., Baltimore, MD
OSTI Identifier:
6620088
Resource Type:
Journal Article
Journal Name:
Biochemistry; (United States)
Additional Journal Information:
Journal Volume: 26:2
Country of Publication:
United States
Language:
English
Subject:
59 BASIC BIOLOGICAL SCIENCES; CARBON 14 COMPOUNDS; TRACER TECHNIQUES; FOLIC ACID; BIOCHEMISTRY; CONFIGURATION INTERACTION; LIGASES; ENZYME ACTIVITY; ENZYME INHIBITORS; GLUTAMIC ACID; LIVER; SWINE; AMINO ACIDS; ANIMALS; AROMATICS; AZAARENES; BODY; CARBOXYLIC ACIDS; CHEMISTRY; DIGESTIVE SYSTEM; DOMESTIC ANIMALS; DRUGS; ENZYMES; GLANDS; HEMATINICS; HEMATOLOGIC AGENTS; HETEROCYCLIC COMPOUNDS; HYDROXY COMPOUNDS; ISOTOPE APPLICATIONS; LABELLED COMPOUNDS; MAMMALS; ORGANIC ACIDS; ORGANIC COMPOUNDS; ORGANIC NITROGEN COMPOUNDS; ORGANS; PTERIDINES; VERTEBRATES; VITAMIN B GROUP; VITAMINS; 550201* - Biochemistry- Tracer Techniques

Citation Formats

George, S, Cichowicz, D J, and Shane, B. Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues. United States: N. p., 1987. Web.
George, S, Cichowicz, D J, & Shane, B. Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues. United States.
George, S, Cichowicz, D J, and Shane, B. 1987. "Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues". United States.
@article{osti_6620088,
title = {Mammalian folylpoly-. gamma. -glutamate synthetase. 3. Specificity for folate analogues},
author = {George, S and Cichowicz, D J and Shane, B},
abstractNote = {A variety of folate analogues were synthesized to explore the specificity of the folate binding site of hog liver folypolyglutamate synthetase and the requirements for catalysis. Modifications of the internal and terminal glutamate moieties of folate cause large drops in on rates and/or affinity for the protein. The only exceptions are glutamine, homocysteate, and ornithine analogues, indicating a less stringent specificity around the delta-carbon of glutamate. It is proposed that initial folate binding to the enzyme involves low-affinity interactions at a pterin and a glutamate site and that the first glutamate bound is the internal residue adjacent to the benzoyl group. Processive movement of the polyglutamate chain through the glutamate site and a possible conformational change in the protein when the terminal residue is bound would result in tight binding and would position the ..gamma..-carboxyl of the terminal glutamate in the correct position for catalysis. The 4-amino substitution of folate increases the on rate for monoglutamate derivatives but severely impairs catalysis with diglutamate derivatives. Pteroylornithine derivatives are the first potent and specific inhibitors of folylpolyglutamate synthetase to be identified and may act as analogues of reaction intermediates. Other folate derivatives with tetrahedral chemistry replacing the peptide bond, such as pteroyl-..gamma..-glutamyl-(psi,CH/sub 2/-NH)-glutamate, retain affinity for the protein but are considerably less effective inhibitors than the ornithine derivatives. Enzyme activity was assayed using (/sup 14/C)glutamate.},
doi = {},
url = {https://www.osti.gov/biblio/6620088}, journal = {Biochemistry; (United States)},
number = ,
volume = 26:2,
place = {United States},
year = {Tue Jan 27 00:00:00 EST 1987},
month = {Tue Jan 27 00:00:00 EST 1987}
}