Molecular dynamics simulation of the renin inhibitor H142 in water.

H142 is a synthetic decapeptide designed to inhibit renin, an enzyme acting in the regulation of blood pressure. The inhibiting effect of H142 is caused by a reduction of a -Leu-Val-peptide bond (i. e. C(= O)-NH----CH2-NH). The conformational and dynamical properties of H142 and its unreduced counterpart (H142n) was modelled by means of molecular dynamics simulations. Water was either included explicitly in the simulations or as a dielectric continuum. When water molecules surround the peptides, they remain in a more or less extended conformation through the simulation. If water is replaced by a dielectric continuum, the peptides undergo a conformational change from an extended to a folded state. It is not clear whether this difference is a consequence of a too short simulation time for the water simulations, a force-field artifact promoting extended conformations, or if the extended conformation represents the true conformational state of the peptide. A number of dynamic properties were evaluated as well, such as overall rotation, translational diffusion, side-chain dynamics and hydrogen bonding.