GAS PHASE CONFORMATIONAL BEHAVIOR OF SELENOMETHIONINE: A COMPUTATIONAL ELUCIDATION
S. Mandal1, G. Das2
1Centre of Advanced Study and Department of Chemistry, North-Eastern Hill University, Shillong, 793022, Meghalaya, India
2Faculty of Chemistry, Central Institute of Technology, Kokrajhar (B.T.A.D.), 783370, Assam, India
guna_das78@yahoo.co.in
Keywords: ab initio calculations, selenomethionine conformers, vibrational frequency, HOMO-LUMO energy gap, intramolecular H bonds
Abstract
Selenium containing amino acids are known to play numerous key biological roles in various life-supporting processes. In the current theoretical investigation DFT(B3LYP) and MP2 methods are used to study the gas phase conformers of the selenomethionine molecule in view of their relative stabilities, theoretically predicted harmonic frequencies, HOMO-LUMO energy gaps, rotational constants, and dipole moments. The number and type of intramolecular H-bond interactions existing in the selenomethionine conformers, which play key roles in determining the energy of the conformers, are also analyzed. The predicted geometries as well as the relative stabilities of the conformers suggest that the structural aspects and energies of the conformers may depend on the level of theory and the size of the basis set used. A comparison of the vibrational frequencies furnished in this study with the previous experimental and theoretical results obtained at MP2/6-31++G( d , p ) and B3LYP/6-311++G( d , p ) levels promotes the interpretation of the vibrational spectroscopy data on biologically relevant molecules.
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