Interaction of the D-isomer of 4-methylene glutamate (4-MG) with an active site thiol group of. gamma. -glutamylcysteine synthetase (. gamma. -GCS)

Conference · Thu May 01 04:00:00 EDT 1986 · Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States)

OSTI ID:5272250

Simondsen, R P; Meister, A

..gamma..-GCS has an SH-group at or close to the glutamate binding site. During efforts to find a covalently bound inhibitor, the authors examined interaction of the enzyme with 4-MG with the thought that a glutamate analog with an ..cap alpha..,..beta..-unsaturated moiety might bind to the glutamate site and react with the active site thiol. 4-MG is not a significant substrate, but inhibits in the usual assay. Preincubation of the enzyme with DL-4-MG inactivated markedly and to about the same extent as found after preincubation with half the concentration of D-4-MG (prepared by action of glutamate decarboxylase on DL-4-MG); L-4-MG did not inactivate. Inactivation by 4-MG was decreased in the presence of L-glutamate. Inactivation by 4-MG was prevented by prior treatment of the enzyme with cystamine, which forms a disulfide with the active site thiol. After inactivation of the enzyme with 4-(2-/sup 14/C)MG followed by separation of the enzyme by gel filtration, 0.9 mole of label was found per mole of enzyme, amino acid analysis after acid hydrolysis of the labeled enzyme gave labeled products that include the expected adduct formed by reaction of cysteine with 4-MG.

• Research Organization: Cornell Univ. Medical College, New York, NY
• OSTI ID: 5272250
• Report Number(s): CONF-8606151-
• Conference Information: Journal Name: Fed. Proc., Fed. Am. Soc. Exp. Biol.; (United States) Journal Volume: 45:6
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
BIOCHEMICAL REACTION KINETICS
CARBON 14 COMPOUNDS
CARBOXYLIC ACIDS
COVALENCE
ENZYMES
FILTRATION
GLUTAMIC ACID
ISOMERS
ISOTOPE APPLICATIONS
KINETICS
LABELLED COMPOUNDS
LIGASES
MEMBRANE PROTEINS
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
PROTEINS
REACTION KINETICS
RECEPTORS
SEPARATION PROCESSES
THIOLS
TRACER TECHNIQUES