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

Directionally controlled anchoring of myoglobin, a water-soluble globu lar protein, on a dipalmitoylphosphatidylcholine (DPPC) bilayer has be en 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 myo globin Mb(1a), but not native myoglobin and Mb(2a), is bound to the DP PC bilayer membrane in aqueous dispersion. A cast film of the phosphol ipid and the anchored myoglobin displayed anisotropic ESR signals, whi ch depend on the disposition of the cast film in the magnetic field. T hese results suggest that myoglobin molecules are placed on the lipid bilayer in a fixed orientation by inserting the anchor alkyl chain int o the bilayer. The ESR anisotropy was not observed without the anchor.