Malic enzyme: Tritium isotope effects with alternative dinucleotide substrates and divalent metal ions

Conference · Wed Jan 01 04:00:00 EST 1992 · FASEB Journal (Federation of American Societies for Experimental Biology); (United States)

OSTI ID:6993633

Karsten, W E; Harris, B G; Cook, P F ^[1]

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1. Texas College of Osteopathic Medicine, Fort Worth (United States)

The NAD-malic enzyme from Ascaris suum catalyzes the divalent metal ion dependent oxidative decarboxylation of L-malate to yield pyruvate, carbon dioxide and NADH. Multiple isotope effect studies suggest a stepwise chemical mechanism with hydride transfer from L-malate to NAD occurring first to form oxalacetate, followed by decarboxylation. Utilizing L-malate-2-T, tritium V/K isotope effects have been determined for the hydride transfer step using a variety of alternative dinucleotide substrates and divalent metal ions. Combination of these data with deuterium isotope effects data and previously determined [sup 13]C isotope effects has allowed the calculation of intrinsic isotope effects for the malic enzyme catalyzed reaction. The identity of both the dinucleotide substrate and divalent metal ion has an effect of the size of the intrinsic isotope effect for hydride transfer.

• OSTI ID: 6993633
• Report Number(s): CONF-9202109--
• Conference Information: Journal Name: FASEB Journal (Federation of American Societies for Experimental Biology); (United States) Journal Volume: 6:1
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
ANIONS
BIOLOGICAL EFFECTS
CATIONS
CHARGED PARTICLES
CHEMICAL REACTIONS
COENZYMES
DECARBOXYLATION
ELEMENTS
HYDROGEN COMPOUNDS
IONS
ISOTOPE APPLICATIONS
ISOTOPE EFFECTS
METABOLISM
METALS
NAD
NADH2
NUCLEOTIDES
ORGANIC COMPOUNDS
SUBSTRATES
TRACER TECHNIQUES
TRITIUM COMPOUNDS