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Secondary tritium and solvent deuterium isotope effects as a probe of the reaction catalyzed by porcine recombinant dihydropyrimidine dehydrogenase.
Biochemistry. 1998 Jun 23; 37(25):9156-9.B

Abstract

Dihydropyrimidine dehydrogenase catalyzes the rate-limiting step in the degradation of pyrimidines in mammals, the reduction of uracil or thymine to their 5,6-dihydro derivatives. The reduction of uracil by enzyme-bound reduced flavin involves both proton and hydride transfer. In order to determine whether hydride and proton transfer occur in a concerted or stepwise fashion, and to determine the nature of the transition state for the reduction, secondary tritium kinetic isotope effects were measured in H2O and D2O. The tritium isotope effect using 5-3H-uracil is 0.90 +/- 0.03 in H2O and becomes more inverse, 0.85 +/- 0.04, in D2O. Data are interpreted in terms of a stepwise reduction at C-6 followed by protonation at C-5. A late transition state is proposed for the proton transfer at C-5 of uracil.

Authors+Show Affiliations

Theodor-Boveri-Institut für Biowissenschaften, Physiologische Chemie I, Universität Würzburg, Germany.No affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

9636062

Citation

Rosenbaum, K, et al. "Secondary Tritium and Solvent Deuterium Isotope Effects as a Probe of the Reaction Catalyzed By Porcine Recombinant Dihydropyrimidine Dehydrogenase." Biochemistry, vol. 37, no. 25, 1998, pp. 9156-9.
Rosenbaum K, Jahnke K, Schnackerz KD, et al. Secondary tritium and solvent deuterium isotope effects as a probe of the reaction catalyzed by porcine recombinant dihydropyrimidine dehydrogenase. Biochemistry. 1998;37(25):9156-9.
Rosenbaum, K., Jahnke, K., Schnackerz, K. D., & Cook, P. F. (1998). Secondary tritium and solvent deuterium isotope effects as a probe of the reaction catalyzed by porcine recombinant dihydropyrimidine dehydrogenase. Biochemistry, 37(25), 9156-9.
Rosenbaum K, et al. Secondary Tritium and Solvent Deuterium Isotope Effects as a Probe of the Reaction Catalyzed By Porcine Recombinant Dihydropyrimidine Dehydrogenase. Biochemistry. 1998 Jun 23;37(25):9156-9. PubMed PMID: 9636062.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Secondary tritium and solvent deuterium isotope effects as a probe of the reaction catalyzed by porcine recombinant dihydropyrimidine dehydrogenase. AU - Rosenbaum,K, AU - Jahnke,K, AU - Schnackerz,K D, AU - Cook,P F, PY - 1998/6/24/pubmed PY - 1998/6/24/medline PY - 1998/6/24/entrez SP - 9156 EP - 9 JF - Biochemistry JO - Biochemistry VL - 37 IS - 25 N2 - Dihydropyrimidine dehydrogenase catalyzes the rate-limiting step in the degradation of pyrimidines in mammals, the reduction of uracil or thymine to their 5,6-dihydro derivatives. The reduction of uracil by enzyme-bound reduced flavin involves both proton and hydride transfer. In order to determine whether hydride and proton transfer occur in a concerted or stepwise fashion, and to determine the nature of the transition state for the reduction, secondary tritium kinetic isotope effects were measured in H2O and D2O. The tritium isotope effect using 5-3H-uracil is 0.90 +/- 0.03 in H2O and becomes more inverse, 0.85 +/- 0.04, in D2O. Data are interpreted in terms of a stepwise reduction at C-6 followed by protonation at C-5. A late transition state is proposed for the proton transfer at C-5 of uracil. SN - 0006-2960 UR - https://www.unboundmedicine.com/medline/citation/9636062/Secondary_tritium_and_solvent_deuterium_isotope_effects_as_a_probe_of_the_reaction_catalyzed_by_porcine_recombinant_dihydropyrimidine_dehydrogenase_ L2 - https://doi.org/10.1021/bi973098b DB - PRIME DP - Unbound Medicine ER -