T. Araiso et T. Koyama, FLUIDITY OF GLYCEROL SKELETAL REGION IN PHOSPHOLIPID-BILAYERS - A TIME-RESOLVED FLUORESCENCE DEPOLARIZATION STUDY, Japanese Journal of Physiology, 45(1), 1995, pp. 187-196
The fluidity of glycerol skeletal region in phospholipid bilayer was i
nvestigated by the time-resolved fluorescence depolarization technique
with ero-3-phospho-[N-(4-nitrobenzo-2-oxa-1,3-diazole)] ethanolamine
(NBD-PE) as a fluorescent probe. In this probe, the fluorescent moiety
, 4-nitrobenz-2-oxa-1,3-diazole (NBD), is attached to a nitrogen atom
at the polar head group of phosphatidylethanolamine molecule. When thi
s probe is embedded in a lipid bilayer, the NBD moiety locates near th
e glycerol skeletal region. The time courses of fluorescence anisotrop
y of NBD-PE in dipalmitoylphosphatidylcholine (DPPC) and dimyristoylph
osphatidylcholine (DMPC) bilayers were analyzed using a wobbling-in-co
ne model, in which the molecular motion is characterized by a half con
e angle (theta(c)) and a wobbling diffusion rate (D-w). Values of D-w
of NBD moiety in phospholipid bilayers were found to be on the order o
f 10(7) s(-1) at the physiological temperatures, which is almost the s
ame value as that of the hydrocarbon chain in lipid bilayers. This fac
t indicates that the fluidity in the glycerol skeletal region is simil
ar to that in the hydrocarbon layer.