title: Detailed description of the conformation and location of membrane-bound erythromycin a using isotropic bicelles.
abstract: Although many nonpeptidic drugs target biological membrane and membrane proteins, it is still difficult to define the membrane-bound structure of the drugs. In this study, we utilized bicelles as a membrane model, since the bicelles, which have planar lipid bilayer portions, are thought to be a more appropriate and practical membrane model than micelles. Bicelles with a small diameter allow for measurements of liquid NMR due to fast tumbling in solution. We targeted erythromycin A (EA) as a membrane-binding compound because it is pointed out that the drug interacts with lysosomal membranes, inhibits phospholipase A, and consequently induces phospholipidosis as a side effect. The conformation of EA in the bicelle was successfully determined on the basis of coupling constants and NOEs. Measurements of intermolecular NOEs and paramagnetic relaxation times revealed that the drug is located shallowly in the membrane surface, with the dimethylamino group being close to the phosphate, and the macrolide portion adjacent to upper sides of the acyl chains. This study shows the general utility of isotropic bicelles for detailed conformational and orientational studies of membrane-associated nonpeptidic drugs.
authors.affiliation: Department of Chemistry, Graduate School of Science, Osaka University, 1-16 Machikaneyama, Toyonaka, Osaka 560-0043, Japan. matumori@ch.wani.osaka-u.ac.jp
authors.forename: Nobuaki
authors.initials: N
authors.lastname: Matsumori
authors.forename: Atsushi
authors.initials: A
authors.lastname: Morooka
authors.forename: Michio
authors.initials: M
authors.lastname: Murata
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry*; D002462:Cell Membrane / Q000737:chemistry; D004917:Erythromycin / Q000737:chemistry*; D008051:Lipid Bilayers / Q000737:chemistry*; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008958:Models, Molecular; D008968:Molecular Conformation; D009010:Monte Carlo Method; D010741:Phospholipases A / Q000037:antagonists & inhibitors / Q000737:chemistry
chemical_list: D000900:Anti-Bacterial Agents; D008051:Lipid Bilayers; D008823:Micelles; D004917:Erythromycin; D010741:Phospholipases A