Theoretical Studies of Solvent Effects on the Conformational Stability of Cholinergic Molecules. In: Bergmann ED, Pullman B, editors. Molecular and Quantum Pharmacology. Dordrecht: Springer Netherlands; 1975. pp. 153-78. [DOI: 10.1007/978-94-010-1758-9_12]

A fractional charge model for empirical calculations of peptide-water interactions

The properties of an empirical model of interaction between a water molecule and polar groups of peptides or small peptides are explored. The H2O molecule is represented by a four-point charges distribution. In electron donor groups, a point charge is located on the axis of the lone pairs orbitals in order to introduce some directionality in hydrogen bonds. The effective potential is approximated by the sum of the coulombic interactions between point charges distribution and of a 6--12 atom-atom potential. The coefficients of this last potential are first adjusted by simulating the geometry of the water dimer. Equilibrium configurations of associated polar molecules and H2O predicted by the model are found to be in good agreement with those resulting from more sophisticated ab initio SCF calculations. Interactions between H2O and the side-chains of the cyclic dipeptide C(L-Thr-L-His) are then calculated. It is shown that internal bridging by water is an essential effect of the solvent. The experimental position of the H2O molecule is reproduced, stability of which depends also on intermolecular interactions.

New paths in the molecular orbital approach to solvation of biological molecules

This review is devoted to the presentation of recent developments in a field of theoretical molecular biophysics which seem to open large possibilities for progress in a hitherto relatively unexplored although very important direction. It is concerned with the establishment of a new methodology in the molecular orbital approach to the problem of the solvation of biological molecules. The methodology is still in an initial stage, susceptible of many refinements and its practical applications may also be considered as being in their beginnings. Nevertheless the successes obtained so far and the interest which they aroused in a number of laboratories incite us to present already now the general principles and the available results so as to offer a possibility of evaluating the advantages, present-day limitations and future potentialities of the procedure, which could then be explored by all those interested. This review may thus be said to be to a large extent oriented towards the future, with the acknowledged aim of producing an acceleration and widening of researches in this field. Possible progress in this respect is interesting from a double point of view.