Orientational and motional properties of copper (II) complexes of dibenzotetraaza [14]annulenes in lipid bilayers: an ESR study.
ESR studies of two copper(II) complexes of substituted dibenzotetraaza [14]annulenes, CuL and CuLA, in dimyristoylphosphatidylcholine (DMPC) and egg yolk phosphatidylcholine (EYPC) are reported. Our data show that both complexes partition into the membranes and that the rotational motion of CuL is faster than CuLA. Analysis of the ESR spectra of these complexes in DMPC vesicles indicate that the Cu-motion parameter, which is a measure of the degree of resolution of the nitrogen hyperfine structure, changes abruptly at the main phase transition. At 1 mole %, both complexes lowered the fluid/gel phase transition temperature by 2 degrees C as measured by the Cu-motion parameter. A gradual change of the Cu-motion parameter is observed in EYPC liposomes over the same temperature range. ESR spectra of both CuL and CuLA in oriented membranes reveal that both complexes are well oriented with the plane of the complex perpendicular to the bilayer surface.
Pezeshk
A
A
Chemistry Department, Moorhead State University, Minnesota 56563.
Pezeshk
V
V
Subczynski
W K
WK
D003300:Copper; D004134:Dimyristoylphosphatidylcholine; D004578:Electron Spin Resonance Spectroscopy; D008081:Liposomes; D008968:Molecular Conformation; D010713:Phosphatidylcholines; D011166:Porphyrins
D008081:Liposomes; D010713:Phosphatidylcholines; D011166:Porphyrins; D003300:Copper; D004134:Dimyristoylphosphatidylcholine