Conformational analysis of Met-enkephalin in both aqueous solution and in the presence of sodium dodecyl sulfate micelles using multidimensional NMR and molecular modeling.

Proton and 13C chemical shift assignments are reported for the neuropeptide Met-enkephalin (ME) in both aqueous solution and in the presence of 50 mM sodium dodecyl sulfate (SDS). Rotating frame nuclear Overhauser enhancement spectroscopy was used to qualitatively describe interproton distances. These distances were then used as restraints in the distance geometry based molecular modeling program Dspace, developed by Hare Research to generate sets of conformations of ME. The resulting aqueous solution conformations of ME were determined to exhibit characteristic of an extended random-coil polypeptide with no distinguishable secondary structure. The resulting set of solution conformations of ME in the presence of 50 mM SDS exhibited characteristics of an amphiphilic type IV beta turn that are stabilized by hydrophobic aromatic-aromatic interactions between the side chains of Tyr1 and Phe4.