Equilibrium of Formation of the 6-Carbanion of UMP, a Potential Intermediate in the Action of OMP Decarboxylase
- 1 November 2002
- journal article
- research article
- Published by American Chemical Society (ACS) in Journal of the American Chemical Society
- Vol. 124 (47) , 13986-13987
- https://doi.org/10.1021/ja021073g
Abstract
There has been some speculation that the C-6 position in UMP may be unusually acidic, stabilizing a carbanion that is generated at this position during OMP decarboxylation. On the basis of the rate of OH- catalyzed deuterium exchange at elevated temperatures we estimate that the pKa value for ionization at C-6 of dimethyl uracil is 34 ± 2 in water. The same method yields a value of 37 ± 2 for ionization at C-2 of thiophene in good agreement with the value determined by polarographic methods. The barrier to proton release (46 kcal/mol) is even higher than that for CO2 release from orotic acid derivatives.Keywords
This publication has 9 references indexed in Scilit:
- Catalytic Proficiency: The Unusual Case of OMP DecarboxylaseAnnual Review of Biochemistry, 2002
- Remarkable Rate Enhancement of Orotidine 5‘-Monophosphate Decarboxylase Is Due to Transition-State Stabilization Rather Than to Ground-State DestabilizationBiochemistry, 2000
- Formation and Stability of Organic Zwitterions in Aqueous Solution: Enolates of the Amino Acid Glycine and Its DerivativesJournal of the American Chemical Society, 2000
- The crystal structure and mechanism of orotidine 5′-monophosphate decarboxylaseProceedings of the National Academy of Sciences, 2000
- A Proficient EnzymeScience, 1995
- Thiazolium C(2)-proton exchange: structure-reactivity correlations and the pKa of thiamin C(2)-H revisitedBiochemistry, 1988
- Sexadentate Chelate Compounds. VIJournal of the American Chemical Society, 1953
- The Thermodynamics of Aqueous Solutions of Sodium Chloride at Temperatures from 15-45° from e. m. f. Measurements on Cells with TransferenceJournal of the American Chemical Society, 1943
- THE REFRACTIVE INDICES OF ALCOHOL-WATER MIXTURES.1Journal of the American Chemical Society, 1908