Stereospecific binding of morphine to phosphatidyl serine.

By measuring the adsorption of 14C-morphine to a surface film at an air-water interface, it was shown that morphine binds to phosphatidyl serine in a 1:1 molar ratio. With the use of levorphanol and the inactive d-isomer, dextrorphan, it could be demonstrated that the interaction was stereospecific. A Lineweaver-Burk plot disclosed that levorphanol and morphine competitively interacted with the lipid; the Km for morphine was 1.