Ring transformations of heterocycles with nucleophilic reagents. 34. Frontier-orbital interactions in the reaction of 5-nitropyrimidine with electron-rich olefins. An example of superjacent orbital control

Plas, H. C. van der; Marcelis, Antonius T. M.; Ham, D.M.W. van den; Verhoeven, J. W.

doi:10.1021/jo00371a030

Cited by 19 publications

(2 citation statements)

References 3 publications

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“…The light-excited, reduced, and deprotonated flavin possesses an estimated redox potential of −2.8 V . The potential for the reduction of the dimer unit is approximately −2.2 V, and the reduction potentials of the deazaflavins are likely to be between −0.8 and −1.5 V . An electron transfer from the light excited, reduced, and deprotonated flavin to the deazaflavin is, consequently, thermodynamically more favorable than that to the dimer unit.…”

Section: Resultsmentioning

confidence: 99%

Efficient Light-Dependent DNA Repair Requires a Large Cofactor Separation

Epple¹,

Carell²

1999

J. Am. Chem. Soc.

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DNA photolyases are repair enzymes which split (repair) UV-induced cyclobutane DNA lesions. Critical steps in the light-driven repair reaction are the absorption of light by a deazaflavin or methenyl tetrahydrofolate cofactor and the transfer of the excitation energy to a reduced and deprotonated FADH- cofactor, which initiates an electron transfer to the dimer lesion. Although most efficient energy transfer requires a close cofactor arrangement, there is a separation of >17 Å between the cofactors in photolyases. To determine the effect of the large cofactor distance on the repair efficiency, a systematic study with model compounds was performed. A series of compounds were synthesized which contain a model DNA lesion covalently connected to a flavin and a deazaflavin. While the flavin−dimer lesion distance was kept constant in all model compounds, the flavin−deazaflavin distance was incrementally increased. Investigation of the dimer cleavage efficiency shows that compounds with a large cofactor separation possess a low energy-transfer efficiency but split the dimer most efficiently within a few minutes. Model compounds with a close cofactor orientation feature a highly efficient energy transfer from the deazaflavin to the flavin. They are, however, unable to perform the repair of the dimer lesion. At very short cofactor distances, the light-driven repair process is fully inhibited. This is explained by a competitive electron transfer between both cofactors, which hinders the electron transfer to the dimer lesion and hence the dimer splitting. The presented data suggest that the large cofactor separation (17 Å) found in photolyases is a critical parameter that determines the DNA repair efficiency by photolyases.

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Section: Resultsmentioning

confidence: 99%

Efficient Light-Dependent DNA Repair Requires a Large Cofactor Separation

Epple¹,

Carell²

1999

J. Am. Chem. Soc.

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“…From 1,2,3-triazines 1,2,3-Triazine 18, when reacting with the pyrrolidinocycloalkenes (2,n=1,2, 4,6,8) in dry chloroform at 100-120 o C gives, usually in moderate-to-poor yields, the corresponding 2,3-cycloalkenopyridines 19.…”

Section: 12mentioning

confidence: 99%