[Conformation of the enkephalin cycloanalog Lys-Tyr-Gly-Gly-Phe-Leu-]

The spatial structure of an enkephaline cycloanalogue Lys-Tyr-Gly-Gly-Phe-Leu--has been investigated by means of energy calculations, fluorescence and CD-spectroscopy. Despite the high conformational mobility of the cycloanalogue, little resemblance exists between its and parent peptide's low-energy structures. Conformational factors for possible mechanisms of interaction between specific enkephalin receptors and cycloanalogue are discussed.