Complexes of [Met5] and [Leu5]enkephalin amides with 18-crown-6-ether have been studied in CDCl3 solution by means of 500 MHz NMR spectroscopy, in order to simulate two of the features of the opioid receptor: the apolar environment and the binding of the charged N atom. Contrary to all previous studies in polar solvents the NH resonances are spread in a huge range (ca. 4 ppm) as in the spectra of rigid cyclic peptides. The two observed intramolecular hydrogen bonds are consistent with the existence of a single, folded, conformation, i.e. a C10 beta-turn in which the Phe4 NH is linked to the Tyr1 CO group.
Experimental simulation of the environment of the δ opioid receptor. A 500 MHz study of enkephalins in CDCl3
PASTORE, ANNALISA
1984-01-01
Abstract
Complexes of [Met5] and [Leu5]enkephalin amides with 18-crown-6-ether have been studied in CDCl3 solution by means of 500 MHz NMR spectroscopy, in order to simulate two of the features of the opioid receptor: the apolar environment and the binding of the charged N atom. Contrary to all previous studies in polar solvents the NH resonances are spread in a huge range (ca. 4 ppm) as in the spectra of rigid cyclic peptides. The two observed intramolecular hydrogen bonds are consistent with the existence of a single, folded, conformation, i.e. a C10 beta-turn in which the Phe4 NH is linked to the Tyr1 CO group.File in questo prodotto:
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