Multiple isotope effects as a probe of the tartrate dehydrogenase-catalyzed oxidative decarboxylation of D-malate

• Autorzy: Karsten W. , Cook P.
• Konferencja: Proceedings of the International Conference “2001 an Isotope Odyssey: New Application for a New Millenium", June 24-29, 2001, Zakopane, Poland
• Języki publikacji: EN

Abstrakty

EN

A change in the dinucleotide reactant from NAD+ to the more oxidizing APAD+ in the malic enzyme reaction results in a change in the mechanism of oxidative decarboxylation of malate from stepwise to concerted [7]. In order to determine whether this is a phenomenon general to metal ion dependent â-hydroxyacid oxidative decarboxylases, tartrate dehydrogenase, which catalyzes a reaction diastereotopic to malic enzyme, was studied using the technique of multiple isotope effects. A primary deuterium isotope effect of 1.41 on V/Kmalate was measured, as well as a primary 13C-isotope effect of 1.0096. A decrease in the measured value of the 13C-isotope effect to 1.0078 is consistent with a stepwise mechanism, as observed for malic enzyme. The 13C-isotope effect with thioNAD+ also decreases from a value of 1.0053 using D-malate to 1.0009 using D-malate-2-D, consistent with stepwise oxidative decarboxylation with this alternative dinucleotide substrate. The data suggest that the change

Słowa kluczowe

EN

isotope effects; malic enzyme; oxidative decarboxylation; tartrate dehydrogenase

• Wydawca: Institute of Nuclear Chemistry and Technology
• Czasopismo: Nukleonika
• Rocznik: 2002
• Tom: Vol. 47,suppl.1
• Strony: 13--15
• Opis fizyczny: Bibliogr. 15 poz., rys.

Twórcy

autor

Karsten W.

• Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, Oklahoma, 73019, USA, Tel.: [phone], Fax: [phone]

autor

Cook P.

• Department of Chemistry and Biochemistry, University of Oklahoma, 620 Parrington Oval, Norman, Oklahoma, 73019, USA, Tel.: [phone], Fax: [phone]

Bibliografia

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