MOL3D--a modular and interactive program for molecular modeling and conformational analysis: II. Extended modules.

The new release of MOL3D, a molecular modeling program written in FORTRAN, contains not only enhanced graphic capabilities, but also an improved module for intermolecular calculations that allows rigid and flexible docking. Various interfaces have been added to some well-known and widely diffused programs, such as MM2, AMBER and MOPAC, and to the Cambridge Crystallographic Database. Finally a graph manager and a samples database have been added, which allow efficient searches with various requirements concerning structural templates, pharmacophoric three-dimensional (3D) constraints, and the field of biological activity, if any.

Computational analysis of conformational behavior of cholecystokinin fragments. I-CCK4, CCK5, CCK6 and CCK7 molecules.

A conformational analysis has been performed on several peptide fragments (CCK4 to CCK7) of the cholecystokinin neuromodulator. The Monte-Carlo Metropolis method was used to explore the conformational space of all these flexible units and different electric charge distributions were introduced in order to mimic pH effects. Results agree reasonably well with experimental data from NMR and fluorescence experiments.