جستجوی مقالات مرتبط با کلیدواژه « آلانین » در نشریات گروه « فیزیک »

In this paper, Density Functional Theory (DFT) was utilized for the calculation of the hyperfine coupling constant and the g tensor alanine radicals at different crystal temperatures. The cluster approach was used for considering the effects of crystal environment. In the cluster approach, the careful selection of the cluster size is very important for the geometry structure of alanine and the EPR parameters of alanine radicals. The geometry structure of alanine and the EPR parameters of alanine radicals showed a good agreement with the experiment data when 6 alanine molecules had hydrogen bonds with the central alanine or alanine radicals. Further, bigger clusters could even lead to an incorrect description of the geometry structure of alanine and EPR parameters of alanine radicals in the condensed phase.

In this study, based on Density Functional Theory (DFT), the effect of solution on the g-tensor, hyperfine coupling constant of atoms and finally the EPR spectrum of alanine free radicals induced by ionizing radiation such as electron and gamma was investigated using implicit models such as COSMO, and explicit models such as introducing hydrogen bonds to the cluster structures. The obtained results confirmed a good consistency between the g-tensor and hyperfine coupling constant of atoms and the experimental data in the solution as well as qualitatively in the crystal by the introduction of the hydrogen bond of the water molecule to the cluster models. The use of different clusters in constituting hydrogen bonds between water molecule and radicals indicated that in the first shell, four, seven and six water molecules were needed for R1, R2 and R3 radicals, respectively. Moreover, the effect of solution on EPR spectrum was analyzed in a manner that the identity of the radical remained unchanged.