Maleylacetone cis-trans-isomerase. Mechanism of the interaction of coenzyme glutathione and substrate maleylacetone in the presence and absence of enzyme

Journal Article · Wed May 23 04:00:00 EDT 1979 · J. Am. Chem. Soc.; (United States)

DOI:https://doi.org/10.1021/ja00505a042· OSTI ID:6063052

Seltzer, S; Lin, M

Previous studies with maleylacetone cis-trans-isomerase suggest that the coenzyme, glutathione (GSH), may act as a nucleophile in the enzyme-catalyzed cis-trans isomerization. In the absence of enzyme, reaction of the coenzyme with maleylacetone or its trans isomer, fumarylacetone, has been found to lead to an adduct, S-2-(4,6-dioxoheptanoic acid)glutathione. The same diastereomer of the adduct is formed from either geometric isomer, suggesting that the reaction of GSH with maleylacetone proceeds by a slow catalyzed cis-trans isomerization followed by a rapid reaction of GSH conjugate addition to the trans isomer. This mechanism is confirmed by an isotope dilution experiment and a kinetic method involving repetitive addition of fractional equivalents of GSH to a solution of maleylacetone. The intermediate formed during GSH-catalyzed cis-trans isomerization is suggested to be the dienediol formed by sulfur attack at C-2, and this intermediate undergoes bond rotation and elimination before protonation at C-3 can take place. By analogy and additional evidence, a similar mechanism and intermediate are suggested for the enzyme-coenzyme-substrate reaction. 2 figures, 4 tables.

• Research Organization: Brookhaven National Lab., Upton, NY
• OSTI ID: 6063052
• Journal Information: J. Am. Chem. Soc.; (United States), Journal Name: J. Am. Chem. Soc.; (United States) Vol. 101:11; ISSN JACSA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
550200 -- Biochemistry
59 BASIC BIOLOGICAL SCIENCES
ADDUCTS
CARBOXYLIC ACIDS
CHEMICAL REACTION KINETICS
CHEMICAL REACTION YIELD
CHEMICAL REACTIONS
COENZYMES
DATA
DATA FORMS
ENZYME ACTIVITY
ENZYMES
EXPERIMENTAL DATA
GLUTATHIONE
HYDROXY ACIDS
INFORMATION
ISOLATED VALUES
ISOMERASES
ISOMERIZATION
ISOMERS
KETONES
KINETICS
MAGNETIC RESONANCE
NUCLEAR MAGNETIC RESONANCE
NUMERICAL DATA
ORGANIC ACIDS
ORGANIC COMPOUNDS
PEPTIDES
POLYPEPTIDES
PROTEINS
REACTION INTERMEDIATES
REACTION KINETICS
RESONANCE
SPECTRA
ULTRAVIOLET SPECTRA
YIELDS