ANISOTROPIC INCORPORATION OF LIPID-ANCHORED MYOGLOBIN INTO A PHOSPHOLIPID-BILAYER MEMBRANE

Directionally controlled anchoring of myoglobin, a water-soluble globular protein, on a dipalmitoylphosphatidylcholine (DPPC) bilayer has been successfully conducted. Lipid-anchored myoglobin was obtained from a monoalkylated heme derivative and apomyoglobin. It was indicated by gel filtration and ultrafiltration studies that the lipid-anchored myoglobin Mb(1a), but not native myoglobin and Mb(2a), is bound to the DPPC bilayer membrane in aqueous dispersion. A cast film of the phospholipid and the anchored myoglobin displayed anisotropic ESR signals, which depend on the disposition of the cast film in the magnetic field. These results suggest that myoglobin molecules are placed on the lipid bilayer in a fixed orientation by inserting the anchor alkyl chain into the bilayer. The ESR anisotropy was not observed without the anchor.