Influence of metal ions and a local anesthetic on the conformation of the choline group of phosphatidylcholine bilayers studied by Raman spectroscopy

• Published in: Biochimica et biophysica acta Vol. 854; no. 2; p. 213
• Main Authors: Akutsu, H, Suezaki, Y, Yoshikawa, W, Kyogoku, Y
• Format: Journal Article
• Language: English
• Published: Netherlands 29-01-1986
• Subjects: Anesthetics, Local - pharmacology; Calcium - pharmacology; Chemical Phenomena; Chemistry, Physical; Choline; Dibucaine - pharmacology; Europium - pharmacology; Lanthanum - pharmacology; Lipid Bilayers; Magnetic Resonance Spectroscopy; Metals - pharmacology; Phosphatidylcholines; Spectrum Analysis, Raman
• ISSN: 0006-3002
• DOI: 10.1016/0005-2736(86)90113-6

A Raman band assigned to the 'totally' symmetric stretching vibration of the choline C-N bonds is relatively strong and sensitive to the conformation of the choline backbone (Akutsu, H. (1981) Biochemistry 20, 7359-7366). By monitoring this Raman band, the influence of Eu3+, La3+, Ca2+ and a local anesthetic, dibucaine, on the conformation of the choline group was examined for the bilayers of dipalmitoylphosphatidylcholine and those of deuterated one at the choline methyl group (-N(C2H3)3). NMR lanthanide-shift studies proposed that the interaction with metal ions induces a conformational change from the gauche to the trans form in the O-C-C-N+ backbone of the choline group. However, present Raman work clearly showed that neither metal ions nor anesthetics induce such a conformational change. Therefore, a structural change in the polar group detected by 2H-NMR on addition of metal ions should not include a significant conformational change in the choline group as well. Deuterated phosphatidylcholine used here was proved to be more suitable for the direct detection of the amount of the trans conformation by Raman spectroscopy than the nondeuterated one. The spectra of the deuterated compound in the gel and liquid-crystalline states confirmed that the trans conformation of the choline group does not appear at all in both states.