Ultraviolet resonance Raman study on the binding mode of enkephalin to phospholipid membranes
| Autor: | Hideo Takeuchi, Issei Harada, Yoshikazu Ohtsuka |
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| Rok vydání: | 1992 |
| Předmět: | |
| Zdroj: | Journal of the American Chemical Society. 114:5321-5328 |
| ISSN: | 1520-5126 0002-7863 |
| Popis: | Ultraviolet Resonance Raman spectra have been measured of Met-enkephalin (Tyr-Gly-Gly-Phe-Met) and Leu- enkephalin (Tyr-Gly-Gly-Phe-Leu) incorporated into phospholipid liposomes. The 213-nm Raman spectra in the amide I and III regions have shown that these opioid peptides take a folded conformation in the lipid-bound state. The environments of aromatic side chains of Tyr1 and Phe4 are monitored by the 240-nm Raman scattering intensities of the side chain vibrations. Tyr Raman bands generally gain intensity on going from aqueous solution to the liposome-bound state, indicating that the phenolic ring of Tyr is buried in the hydrophobic region of the lipid bilayer. On the other hand, Phe does not show intensity change, suggesting that the Phe side chain is exposed to the aqueous phase or located in the hydrophilic region of the bilayer. The insertion of the Tyr side chain into the membrane is deeper for Met-enkephalin than for Leu-enkephalin. Paralleling experiments on (Trp4) Met-enkephalin (Tyr-Gly-Gly-Trp-Met) have shown that this peptide also takes a folded conformation in liposomes with the Tyr side chain inserted into the membrane hydrophobic interior. The Trp side chain is located in the hydrophilic region as in the case of Phe side chain of natural enkephalins. The degree of insertion of the Tyr side chain into membrane bilayers correlates with the receptor affinity and opiate activity of the peptide. |
| Databáze: | OpenAIRE |
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