Computational studies conformational mobility

Chana, A. Concejero, M.A. de Fmtos, M. Gonzalez, M.J. Herradon, B. Computational studies on biphenyl derivatives. Analysis of the conformational mobility, molecular electrostatic potential, and dipole moment of chlorinated biphenyl Searching for the rationalization of the selective toxicity of polychlorinated biphenyls (PCBs). Chem. Res. Toxicol. 2002, 15. 1514-1526. 

TTie CNDO/2 method [46] of Pople et al. was chosen for these types of studies because its computational simplicity allows the feasible consideration of large, complex, and conformationally mobile systems such as cyclodextrin host-guest systems. In contrast to ab initio methods, which seek to directly derive molecular properties from the basic principles of quantum mechanics, CNDO/2 is a semiempirical method, which means that not only are the expressions for wavefunctions simplified algebraically, but also that certain coefficients associated with the resulting approximate functions are arbitrarily assigned in order to duplicate experimental data. 

Recently, we have addressed a problem previously described concerning the relationship between morphine and enkephalin. The inherent mobility of the enkephalin linear peptide framework, its rapid degradation in vivo, and the existence of multiple receptor subtypes, have hampered the assessment of its bioactive conformations. Conformationally constrained peptides or pepti-domimetics should facilitate this task. Several turn conformations have been proposed based on computational models,X-ray crystallography and spectroscopic studies. " - - ... 

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