Dynamical search for bis-penicillamine enkephalin conformations

Area of Science:

• Computational chemistry
• Molecular modeling
• Biophysics

Background:

• Understanding peptide conformation is crucial for drug design.
• Enkephalins, like DPDPE, are opioid peptides with therapeutic potential.
• Previous studies suggested amphiphilic structures for DPDPE.

Purpose of the Study:

• To explore the conformational landscape of [D-Pen2,D-Pen5]enkephalin (DPDPE) using quenched molecular dynamics.
• To analyze the energy distribution of DPDPE conformations in a continuum solvent.
• To identify structural features of low-energy DPDPE conformers.

Main Methods:

• Quenched molecular dynamics simulations.
• Conformational searching in a continuum solvent model.
• Energy minimization for comparison.

Main Results:

• A Gaussian-like distribution of conformations as a function of energy was observed for DPDPE.
• This distribution differs from sharp bands in crystal forms and broad glasslike states of simple liquids.
• Lowest energy conformers exhibited structural similarities to those from energy minimization.
• Many low-energy configurations were amphiphilic, with distinct polar and nonpolar surfaces.

Conclusions:

• Quenched molecular dynamics is a viable conformational search technique for cyclic peptides.
• The Gaussian energy distribution suggests unique conformational behavior for DPDPE.
• The prevalence of amphiphilic structures in low-energy states supports prior modeling studies incorporating NOE data.