Conformational preferences of Leu-enkephalin in reverse micelles as membrane-mimicking environment
✍ Scribed by Sabine Rudolph-Böhner; Daniela Quarzago; Michael Czisch; Ulf Ragnarsson; Luis Moroder
- Publisher
- Wiley (John Wiley & Sons)
- Year
- 1997
- Tongue
- English
- Weight
- 400 KB
- Volume
- 41
- Category
- Article
- ISSN
- 0006-3525
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✦ Synopsis
Enkephalin represents one of the bioactive peptide molecules most extensively investigated both in solution and in the crystal state. Depending upon the environment chosen for such studies, three main conformational states were identified for this flexible, linear pentapeptide-i.e., an extended conformation, a single-bend, and a double-bend structure. Since CD and Fourier transform ir (FTIR) spectra of Leu-enkephalin solubilized in negatively charged reverse micelles of bis(2-ethylhexyl)sulfosuccinate sodium salt/isooctane/water were supportive of a restricted conformational space of the aromatic side chains and of a bended type fold, we have analyzed by nmr the conformational preferences of Leu-enkephalin in reverse micelles using a synthetic [ 13 C, 15 N]-backbone-labeled sample. The overall conformation derived from nuclear Overhauser effect spectroscopy (NOESY) and 15 N-filtered rotating frame NOESY (ROESY) spectra and by distance geometry calculations is a double-bend fold of the backbone that is comparable to one of the known x-ray structures. Thereby the tyrosine side chain is inserted into the hydrophobic core of the reverse micelles in a restrained conformational space as well evidenced by NOEs between the aromatic ring protons and the surfactant. The proximity of the aromatic rings of tyrosine and phenylalanine indicate a preferred structure consistent with the postulated conformation of the opioid peptide in the d-receptor-bound state. These results confirm the interesting and promising properties of reverse micelles as membrane mimetica.