The endogenous cannabinoid ligand anandamide is biosynthesized from membrane phospholipid precursors and is believed to reach its sites of action on the CB1 and CB2 receptors through fast lateral diffusion within the cell membrane. To gain a better insight on the stereochemical features of its association with the cell membrane and its interaction with the cannabinoid receptors, we have studied its conformation, location, and dynamic properties in a dipalmitoylphosphatidylcholine multilamellar model membrane bilayer system. By exploiting the bilayer lattice as an internal threedimensional reference grid, the conformation and location of anandamide were determined by measuring selected inter-and intramolecular distances between strategically introduced isotopic labels using the rotational echo double resonance (REDOR) NMR method. A molecular model was proposed to represent the structural features of our anandamide/lipid system and was subsequently used in calculating the multispin dephasing curves. Our results demonstrate that anandamide adopts an extended conformation within the membrane with its headgroup at the level of the phospholipid polar group and its terminal methyl group near the bilayer center. Parallel static 2 H NMR experiments further confirmed these findings and provided evidence that anandamide experiences dynamic properties similar to those of the membrane phospholipids and produces no perturbation to the bilayer. Our results are congruent with a hypothesis that anandamide approaches its binding site by laterally diffusing within one membrane leaflet in an extended conformation and interacts with a hydrophobic groove formed by helices 3 and 6 of CB1, where its terminal carbon is positioned close to a key cysteine residue in helix 6 leading to receptor activation.The membrane lipid bilayer is a ubiquitous molecular assembly into which are embedded a variety of proteins, natural hormones, and neurotransmitters. Accumulated evidence indicates that many fatty acid-derived lipophilic neurotransmitters are synthesized, stored, and degraded and also exert their functions within the lipid membrane (1, 2). Therefore, it has been suggested that the conformation, location, and orientation of the ligand in the membrane are critical in determining its ability to reach and interact productively with its site of action (3-5). Exploring the conformational and dynamic properties of these ligands in the membrane can lead to a better understanding of the molecular features involved in their interactions with the target proteins (6).N-Arachidonoylethanolamine (anandamide), initially isolated from mammalian brain, has been identified as an endogenous ligand for the two known G protein-coupled cannabinoid receptors (CB1 and CB2) (7). This endocannabinoid exerts its activity by modulating several physiological functions such as pain, cognition, and memory. Site-directed mutagenesis evidence has shown that the anandamide binding sites are embedded in the trans-membrane helices of the receptor (8, 9). This correlates wel...

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The oxidative dehydrogenation of phenol compounds, as well as polymer formation from these monomers, was studied by UV-vis and Mo ¨ssbauer spectroscopy using a novel biological catalyst hematin. The mechanism of the polymerization reaction was also followed in various pH environments. Phenol radicals were formed by a two-step electron transfer reaction catalyzed by hematin in the presence of peroxide, and polymer was formed from phenol radicals by a noncatalytic reaction. This mechanism partially explains the analogous catalytic polymerization activity of horseradish peroxidase.

In an effort to determine the stereochemical requirements for pharmacological activity among the series of nonclassical cannabinoids synthesized at Pfizer, we have studied the conformational properties of the parent bicyclic analog CP-47,497. For this study, we have used a combination of solution NMR and theoretical computational approaches. The energetically favored conformation has the phenolic ring almost perpendicular to the cyclohexanol ring which exists in a chair conformation. The OH bond of the phenol is preferentially coplanar with the aromatic ring and points toward the C2 ring proton, while the dimethylheptyl side chain adopts a conformation almost perpendicular to the aromatic ring. The conformational features of this nonclassical cannabinoid analog closely resemble those of its classical counterparts. The only apparent difference is the small dihedral angle (psi 1 = 62 degrees) between the planes of the two rings of CP-47,497 compared to that of the tricyclic tetrahydro- or hexahydrocannabinol analogs (psi 1 = 137 degrees). However, CP-47,497 can be perfectly superimposed over the respective tricyclic analog by rotation around the Ph-cyclohexyl bond (C6-C7 bond) and assume a conformation which is energetically higher than the preferred one by 3.0 kcal/mol. It can be argued that such a conformation may be acquired by the nonclassical analog during its interaction with the active site.

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The magnetic behaviour of LaZ-,Sr,CuO, was studied using the method of muon spin rotation (pSR). We found that the system orders magnetically for x S 0.05 and the Neeltemperatures vary from 250 K for x = 0 to 6 K for x = 0.05. In spite of these drastic changes of the Neel-temperatures, the extrapolated internal fields at T = 0 K are similar for all samples indicating that the moments at the magnetic (Cu) ions are not changed appreciably. The depolarization rates measured in this experiment are analyzed in terms of an inhomogeneous field distribution in the sample.