Partitional and motional properties of a spin-labeled daunomycin in lipid bilayers. An ESR study.
The partition coefficient of a spin-labeled daunomycin (DAU-SL) in dimyristoylphosphatidylcholine membrane has been determined using the electron spin resonance (ESR) method. The experiment was carried out as a function of temperature between 5 degrees C and 35 degrees C, giving partition coefficients between 2 and 6 without abrupt change at the phase transition. The thermodynamic parameters on transferring the DAU-SL from the aqueous phase to the lipid bilayer were also calculated. The calculated values are: delta H = 6.11 kcal/mol and delta S = 23 cal/K mol. The partitioning of the DAU-SL and its motion in the membrane were investigated in a wide range of pH (4-10.3). The data show that pH has no effect on partitioning of the DAU-SL which suggest that the drug exists in the uncharged form in the bilayer.
Pezeshk
A
A
Department of Chemistry, Moorhead State University, Minnesota 56563.
Pezeshk
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V
Wojas
J
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Subczynski
W K
WK
D055598:Chemical Phenomena; D002627:Chemistry, Physical; D003630:Daunorubicin / Q000737:chemistry* / Q000378:metabolism; D004134:Dimyristoylphosphatidylcholine; D004578:Electron Spin Resonance Spectroscopy; D006863:Hydrogen-Ion Concentration; D008051:Lipid Bilayers / Q000378:metabolism*; D008081:Liposomes / Q000378:metabolism; D013113:Spin Labels; D013816:Thermodynamics
D008051:Lipid Bilayers; D008081:Liposomes; D013113:Spin Labels; D004134:Dimyristoylphosphatidylcholine; D003630:Daunorubicin