CONFORMATIONAL ENERGY CALCULATIONS ON ENKEPHALINS AND ENKEPHALIN ANALOGS:

Conformational energy calculations were carried out on the peptide enkephalins (ENK) and selected analogs to find those conformers of low energy. The analogs studied include [D-Ala²]Enk-NH₂, [D-Ala²]Enk, [D-Met², Pro⁵]Enk-NH₂, [D-Ala², D-Phe⁵]Enk, [D-Ala², D-Leu⁵]Enk, [D-Ala², (N-Me)Phe⁴, Met⁵] Enk-NH₂ and [D-Ala², (N-Me)Met⁵]Enk-NH₂. When the low-energy conformers for all the analogs are compared, different allowed backbone conformations are found which orient the functional side-chains such that three classifications of structures appear. Each classification shows a unique configuration of side- chain positions in space even though different backbone conformations are found within each classification.