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Evidence for a folded structure of met‐enkephalin in membrane mimetic systems: 1 H‐nmr studies in sodiumdodecylsulfate, lyso‐phosphatidylcholine, and mixed lyso‐phosphatidylcholine/sulfatide micelles
Author(s) -
Zetta Lucia,
De Marco Antonio,
Zani Giulio,
Cestaro Benvenuto
Publication year - 1986
Publication title -
biopolymers
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.556
H-Index - 125
eISSN - 1097-0282
pISSN - 0006-3525
DOI - 10.1002/bip.360251209
Subject(s) - chemistry , micelle , phosphatidylcholine , hydrogen bond , amide , aqueous solution , nuclear magnetic resonance spectroscopy , enkephalin , molecule , stereochemistry , vesicle , proton nmr , phospholipid , crystallography , membrane , organic chemistry , biochemistry , receptor , opioid
1 H‐nmr spectra of Met‐enkephalin dissolved in aqueous solution of sodiumdodecylsulfate (SDS) micelles are reported as a function of pH and temperature. The temperature behavior of the amide protons is compared with that observed for the same peptide dissolved in aqueous solution of lyso‐phosphatidylcholine (LPC) and lyso‐phosphatidylcholine‐sulfatide (LPC‐SH) micelles. The temperature coefficients are affected by the micelle polarity, which suggests that the peptide backbone is not remote from the micelle surface. pH titration performed in the presence of SDS micelles gives a number of intrinsic and extrinsic p K a values, indicative of a folded structure of the opioid molecule. This conformation is characterized by the existence of an intramolecular hydrogen bond involving the Met‐5 amide proton and an interaction of the N‐terminal residue with the aliphatic side chains of both Phe‐4 and Met‐5.