Taulomerism and Electronic Structure of Biological Pyrimidines

Kwiatkowski, Józef S.; Pullman, Bernard

doi:10.1016/s0065-2725(08)60131-2

Cited by 179 publications

(100 citation statements)

References 822 publications

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“…Because of the systematic disparity between the aqueous phase experimental results and the ab initio calculations involving heterocyclic compounds (2,22,23,29,30) it was decided to investigate the en01 tautomers of the experimentally found C5 adduct and the theoretically preferred C6 adduct. This tautomeric form was chosen on the basis of the favorable relative energy of the en01 tautomer of cytosine as suggested by various theoretical calculations (26)(27)(28)(29).…”

Section: Resultsmentioning

confidence: 99%

“…Interestingly, this experimental-theoretical discrepancy appears to be systematic for a number of N heterocyles (2,22,30). Various factors were considered as the basis for the disparity between experimental and theoretical results including tautomerism of the adducts, kinetic effects, mixing of higher order spin states in calculations of wave functions for doublet adducts, internal H bonding, and solvation aspects.…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

AbInitio SCF MO calculations on the reaction of hydroxyl radical with cytosine

Eatock¹,

Waltz²,

Mezey³

1986

Can. J. Chem.

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. 64,914 (1986).Ab initio calculations have been carried out on the relative stabilities of various possible products of the reaction between cytosine and the OH radical. These products are of importance in modelling radiation damage to living tissues. The preferred theoretical gas-phase addition site is the C6 ring atom according to these calculations. The analysis of a series of possible contributions to solvent effects strongly suggests the predominance of intermolecular H bonds in stabilizing the experimentally observed C5 adduct.BEVERLEY G. EAToCK, WILLIAM L. WALTZ, et PAUL G. MEZEY. Can. J. Chem. 64,914 (1986).On a effectut de calculs ab initio sur les stabilitks relatives de divers produits possibles pour la rkaction de la cytosine avec le radical OH. Ces produits sont importants dans l'klaboration d'un modkle pour les dommages dfis B la radiation dans les tissus vivants. D'apr2s ces calculs thtoriques, le site prkftrt pour l'addition en phase gazeuse est l'atome de carbone C6. L'analyse d'une skrie de contributions possibles aux effets de solvant sugg2re fortement la prkdominance de liaisons hydrogknes intermoltculaires dans la stabilisation de l'adduit en C5 qui est observk expkrimentalement.[Traduit par la revue] Introduction Radiation damage to nitrogen heterocycles has attracted interest due to the relevance of such effects for biologically important systems. As an extension of studies on the reactions of OH radicals with N heterocyclic systems (pyridine, imidazole) (1, 2), we have investigated the attack of OH on the pyrimidine base cytosine. Experimental results on the reaction of OH with cytosine agree that ring addition occurs (3,4), but information on site preference for addition is obtained only by indirect methods (esr, pulse radiolysis) leaving results open to some controversy. Ab initio calculations, however, provide a direct aid to identification of favored product isomers, and have been shown to be useful in past studies, supplementing experimental results (1,2,5,6).Radiation damage to cytosine is of interest because of its status as a component of DNA. Consideration of the N bases of DNA as subjects for ab initio studies favors the pyrimidines, both because of their greater susceptibility to OH attack (7) and the simpler problem that the electronic structure of the pyrimidines represents, as compared to the purine bases. Although more information exists regarding reactions of OH with thymine and uracil, the greater experimental controversy for site preference of OH addition to cytosine lent impetus to the choice of cytosine as a subject for these calculations. A recent paper (8) suggested that site selection of OH attack of cytosine is more discriminating than for the analogous reactions with thymine and uracil and that the major product, in opposition to expectations from the results of our previous studies on OH reactions with N heterocycles (1,2), was the species favored on account of electrophilic interactions rather than being the most electronically delocalized product. These factor...

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Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

AbInitio SCF MO calculations on the reaction of hydroxyl radical with cytosine

Eatock¹,

Waltz²,

Mezey³

1986

Can. J. Chem.

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“…For structural chemists, rare tautomers of DNA bases are of special interest because they exert strong mutational pressures on the genome (Friedberg et al, 2006;Harris et al, 2003;Kwiatkowski & Pullman, 1975). That's why the tautomerism of DNA bases and their biologically active modifications (Kondratyuk et al, 2000;Samijlenko et al, 2001) have been the subject of a great number of theoretical and experimental investigations due to their biochemical significance.…”

Section: Mutagenic Tautomers Of Dna Basesmentioning

confidence: 99%

Elementary Molecular Mechanisms of the Spontaneous Point Mutations in DNA: A Novel Quantum-Chemical Insight into the Classical Understanding

Brovarets’¹,

Kolomiets²,

Hovorun³

2012

Quantum Chemistry - Molecules for Innovations

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“…3 Apart from detection problems of rare tautomers present in proportions lower than 10 -4 , a major difficulty with quantummechanical calculations on relative energies of tautomers represents the geometry approximation used for the respective tautomers.…”

Section: Introductionmentioning

confidence: 99%