CHIRAL RECOGNITION OF ODORANTS (+)-CARVONE AND (-)-CARVONE BY PHOSPHOLIPID MONOLAYERS

Interactions of the odorants (+)- and (-)-carvone With L-alpha-1,2-dipalmitoyl-sn-glycero-3-phosphocholine (L-DPPC) monolayers were studied using surface pressure and surface potential versus area isotherms measured in the temperature range 10-35-degrees-C in the presence and absence of 5 mM odorants in the subphase. The data indicate that the L-DPPC monolayers with (-)-carvone absorb twice as much heat as those with (+)-carvone when compressed at 30-degrees-C. Under the same conditions, monolayers with (-)-carvone undergo a larger entropy change than monolayers with (+)-carvone. The temperature dependence of surface potentials of compressed L-DPPC monolayers exposed to (-)-carvone differs significantly from those exposed to the + isomer. Variations in thermodynamic properties and orientations of molecules within lipid assemblies may contribute to membrane recognition of optical isomers.