LOCATION OF THE TOXIC MOLECULE ABIETIC ACID IN MODEL MEMBRANES BY MAS-NMR

Abietic acid, the major component of conifer oleoresin, is an environm ental toxic molecule with potential hazard to animal and plant life. B eing amphipatic, the study of its location and the interaction with me mbrane components is important to get insight into the mechanism of it s toxic action. High resolution magic angle spinning natural abundance C-13 nuclear magnetic resonance studies have been undertaken in order to assess its location in egg yolk phosphatidylcholine multilamellar vesicles model membranes. C-13 spin-lattice relaxation times in the pr esence of Gd3+, a paramagnetic agent, of both the phospholipid and abi etic acid molecules have been measured in order to obtain information on molecular distances (see J. Villalain, fur. J. Biochem. 241 (1996) 586-593). The molecule of abietic acid is placed in the upper part of the palisade structure of the membrane, its carboxyl group is in close proximity to the phospholipid ester groups and it does not extend bey ond the C4/C7 carbons of the phospholipid molecule. (C) 1997 Elsevier Science B.V.