PLANAR BILAYER-MEMBRANES FROM PHOTOACTIVABLE PHOSPHOLIPIDS

Planar bilayer membranes formed from photoactivable phospholipids have been characterized by low frequency voltametry. Cyclic voltametric measurements were applied for simultaneous registration of planar membrane conductivity and capacitance. The procedure has been utilized to characterize the formation and stability of planar bilayer membranes. Bilayer membranes were formed from N'-(1,2-dimyristoyl-sn-glycero-3-phosphoethyl)-N-((m-3-trifluoromethyldiazirine) phenyl)thiourea (C-14-PED), a head-group photosensitive phospholipid. In situ photoactivation of C-14-PED at wavelengths greater-than-or-equal-to 320 nm altered neither the mean conductivity nor the capacitance of the bilayer. Ionophore (valinomycin) and ion channel (gramicidin) activities were not impaired upon photoactivation. In contrast, bilayer membranes formed from 1,2-bis(hexadeca-2,4-dienoyl)-sn-glycero-3-phosphocholine (C-16-DENPC) revealed short life times. In situ photopolymerization of the diene fatty acids significantly increased the membrane conductivity or led to membrane rupture.