Synthesis and Analysis of Leu- and Met-Enkephalin Analogues Containing Conformational Restriction

Synthesis and Analysis of Leu- and Met-Enkephalin Analogues Containing Conformational Restrictions. Abstract Here we report the design and synthesis of the mimetic of Leu-and Met-enkephalin Tyr-Gly-Gly-Phe-LeuTyr-Gly-Gly-Phe-Met deriving from the substitution of Leu(5) with Ile and Met(5) with Nle. Based upon computational models and X-ray crystallography Boc-Gly-Gly-Phe-X-OMe1 we studied the possibility to obtain only the biologically active conformation of the single peptide introducing (1) a partial conformational restriction with a rigid part of peptidic main chain and (2) a total conformational restriction with end-to-end cyclization. Reference 1) Fenude E., Casalone G., Acta Cryst. Section C 1996 52, 973-978