Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair
The double hydrogen bonding in the adenine-thymine nucleotide base pair has been investigated in the CNDO/S semiempirical approximation. Correlation of the molecular orbitals for the double proton transfer in the normal and tautomeric configurations shows that the π molecular orbitals are only sligh...
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todo:paper_01661280_v88_n3-4_p283_Maranon2023-10-03T15:03:32Z Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair Marañon, J. Grinberg, H. The double hydrogen bonding in the adenine-thymine nucleotide base pair has been investigated in the CNDO/S semiempirical approximation. Correlation of the molecular orbitals for the double proton transfer in the normal and tautomeric configurations shows that the π molecular orbitals are only slightly perturbed, whereas the σ molecular orbitals are delocalized on both units of the base pair. Analysis via perturbation theory in order to elucidate the formation of the hydrogen-bonded complex has been performed. The results suggest that an unsymmetrical charge transfer is involved in the double proton transfer process. The first-order contribution to the perturbed orbital energies of the σ and π molecular orbitals localized on the same unit of the base pair, is predominantly from exchange repulsion energy, whereas the second-order contributor is mainly polarization energy. In the normal configuration of the base pair, the contribution of the deepest σ molecular orbitals (up to -30 eV) to the energy of formation of the hydrogen-bonded complex shows a stabilizing character, whereas at higher energies the opposite trend predominates. The behaviour of the molecular orbitals of the tautomeric configuration is quite different since only some of the σ orbitals (those laying between -40 and -30 eV) localized on thymine help stabilize the complex, whereas the remainder contribute to destabilization of the configuration. Hence the normal configuration of the base pair is more stable than the tautomeric configuration. © 1982. Fil:Grinberg, H. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina. JOUR info:eu-repo/semantics/openAccess http://creativecommons.org/licenses/by/2.5/ar http://hdl.handle.net/20.500.12110/paper_01661280_v88_n3-4_p283_Maranon |
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Universidad de Buenos Aires |
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I-28 |
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R-134 |
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Biblioteca Digital - Facultad de Ciencias Exactas y Naturales (UBA) |
| description |
The double hydrogen bonding in the adenine-thymine nucleotide base pair has been investigated in the CNDO/S semiempirical approximation. Correlation of the molecular orbitals for the double proton transfer in the normal and tautomeric configurations shows that the π molecular orbitals are only slightly perturbed, whereas the σ molecular orbitals are delocalized on both units of the base pair. Analysis via perturbation theory in order to elucidate the formation of the hydrogen-bonded complex has been performed. The results suggest that an unsymmetrical charge transfer is involved in the double proton transfer process. The first-order contribution to the perturbed orbital energies of the σ and π molecular orbitals localized on the same unit of the base pair, is predominantly from exchange repulsion energy, whereas the second-order contributor is mainly polarization energy. In the normal configuration of the base pair, the contribution of the deepest σ molecular orbitals (up to -30 eV) to the energy of formation of the hydrogen-bonded complex shows a stabilizing character, whereas at higher energies the opposite trend predominates. The behaviour of the molecular orbitals of the tautomeric configuration is quite different since only some of the σ orbitals (those laying between -40 and -30 eV) localized on thymine help stabilize the complex, whereas the remainder contribute to destabilization of the configuration. Hence the normal configuration of the base pair is more stable than the tautomeric configuration. © 1982. |
| format |
JOUR |
| author |
Marañon, J. Grinberg, H. |
| spellingShingle |
Marañon, J. Grinberg, H. Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| author_facet |
Marañon, J. Grinberg, H. |
| author_sort |
Marañon, J. |
| title |
Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| title_short |
Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| title_full |
Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| title_fullStr |
Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| title_full_unstemmed |
Semiempirical quantum mechanical calculation of the electronic structure of DNA. Molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| title_sort |
semiempirical quantum mechanical calculation of the electronic structure of dna. molecular orbitals correlation and orbital energy shifts in the double hydrogen bonding of the adenine-thymine base pair |
| url |
http://hdl.handle.net/20.500.12110/paper_01661280_v88_n3-4_p283_Maranon |
| work_keys_str_mv |
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