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'Solvent Effect' in keywords Facet   Publication Year 1999  [X]
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1Author    Piotr Cysewski, Ryszard OlińskiRequires cookie*
 Title    Theoretical Description of the Coding Potential of Diamino-5-formamidopyrimidines  
 Abstract    The results of geometry optimisation of possible Watson-Crick-like pairs o f 2,6-diamino-4-oxy-5-formamidopyrimidine (fapy-adenine) or 4,6-diamino-5-formamidopyrimidine (fapy-guanine) were presented. In the absence of the external field the fapy-adenine is able to form pairs with all four canonical nucleic acid bases. However, pairs with guanine, cytosine and thymine the most stable are. Thus, the potential miscoding abilities may be observed. In contrast, in the presence o f the external field the mispairing abilities of fapy-adenine becom e insignificant since the most stable dimers are formed with thymine. The pairing properties of fapy-guanine are complex and depend on its tatomeric form. In the absence of an external field the 4-enol-6-keto-diam ino tautomer of fapyG is able to form stable dimers with thymine and cytosine, while the 4,6-diketo-diamino tautomer forms the most stable pairs with cytosine and guanine. The presence of the water solvent does not significantly alter the pairing abilities of fapy-guanine. However, pairs with thymine are at least as stable as the Watson-Crick GC pair. TTius, in polar conditions the mispairing potential of fapyG will be extended and may be enriched by potential GC —* AT transition. 
  Reference    Z. Naturforsch. 54c, 239 (1999); received October 26/November 28 1998 
  Published    1999 
  Keywords    Fapy-adenine, Fapy-guanine, Pairing, Miscoding, Solvent Effect 
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 TEI-XML for    default:Reihe_C/54/ZNC-1999-54c-0239.pdf 
 Identifier    ZNC-1999-54c-0239 
 Volume    54 
2Author    Joäo Manuel, Marques Cordeiro, Luiz Carlos, Gomide FreitasRequires cookie*
 Title    Study of Water and Dimethylformamide Interaction by Computer Simulation  
 Abstract    Monte Carlo simulations of water-dimethylformamide (DMF) mixtures were performed in the isothermal and isobaric ensemble at 298.15 K and 1 atm. The intermolecular interaction energy was calculated using the classical 6-12 Lennard-Jones pairwise potential plus a Coulomb term. The TIP4P model was used for simulating water molecules, and a six-site model previously optimised by us was used to represent DMF. The potential energy for the water-DMF interaction was obtained via standard geometric combining rules using the original potential parameters for the pure liquids. The radial distribution functions calculated for water-DMF mixtures show well characterised hydrogen bonds between the oxygen site of DMF and hydrogen of water. A structureless correlation curve was observed for the interaction between the hydrogen site of the carbonyl group and the oxygen site of water. Hydration effects on the stabilisation of the DMF molecule in aqueous solution have been investigated using statistical perturbation theory. The results show that energetic changes involved in the hydration process are not strong enough to stabilise another configuration of DMF than the planar one. 
  Reference    Z. Naturforsch. 54a, 110—116 (1999) 
  Published    1999 
  Keywords    Monte Carlo Simulation, Solvent Effects, Statistical Perturbation Theory, Hydration of Peptides 
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 TEI-XML for    default:Reihe_A/54/ZNA-1999-54a-0110.pdf 
 Identifier    ZNA-1999-54a-0110 
 Volume    54