TY - JOUR
T1 - Lateral diffusion of gramicidin C in phospholipid multibilayers. Effects of cholesterol and high gramicidin concentration
AU - Tank, D. W.
AU - Wu, E. S.
AU - Meers, P. R.
AU - Webb, W. W.
N1 - Copyright:
Copyright 2017 Elsevier B.V., All rights reserved.
PY - 1982
Y1 - 1982
N2 - We have measured the lateral diffusion coefficient (D), of active dansyl-labeled gramicidin C (DGC), using the technique of fluorescence photobleaching recovery, under conditions in which the cylindrical dimer channel of DGC predominates. In pure, hydrated, dimyristoylphosphatidylcholine (DMPC) multibilayers (MBL), D decreases from 6 X 10(-8) cm2/s at 40 degrees C to 3 X 10(-8) cm2/s at 25 degrees C, and drops 100-fold at 23 degrees C, the phase transition temperature (Tm) of DMPC. Above Tm, addition of cholesterol decreases D; a threefold stepwise drop occurs between 10 and 20 mol %. Below Tm, increasing cholesterol increases D; a 10-fold increase occurs between 10 and 20 mol % at 21 degrees C, between 20 and 25 mol % at 15 degrees C, and between 25 and 30 mol % at 5 degrees C. In egg phosphatidylcholine (EPC) MBL, D decreases linearly from 5 X 10(-8) cm2/s at 35 degrees C to 2 X 10(-8) cm2/s at 5 degrees C; addition of equimolar cholesterol reduces D by a factor of 2. Thus this transmembrane polypeptide at low membrane concentrations diffuses quite like a lipid molecule. Its diffusivity in lipid mixtures appears to reflect predicted changes of lateral composition. Increasing gramicidin C (GC) in DMPC/GC MBL broadened the phase transition, and the diffusion coefficient of the lipid probe N-4-nitrobenzo-2-diazole phosphatidylethanolamine (NBD-PE) at 30 degrees C decreases from 8 X 10(-8) cm2/s below 5 mol % GC to 2 X 10(-8) cm2/s at 14 mol % GC; D for DGC similarly decreases from 4 X 10(-8) cm2/s at 2 mol % GC to 1.4 X 10(-8) cm2/s at 14 mol % GC. Hence, above Tm, high concentrations of this polypeptide restrict the lateral mobility of membrane components.
AB - We have measured the lateral diffusion coefficient (D), of active dansyl-labeled gramicidin C (DGC), using the technique of fluorescence photobleaching recovery, under conditions in which the cylindrical dimer channel of DGC predominates. In pure, hydrated, dimyristoylphosphatidylcholine (DMPC) multibilayers (MBL), D decreases from 6 X 10(-8) cm2/s at 40 degrees C to 3 X 10(-8) cm2/s at 25 degrees C, and drops 100-fold at 23 degrees C, the phase transition temperature (Tm) of DMPC. Above Tm, addition of cholesterol decreases D; a threefold stepwise drop occurs between 10 and 20 mol %. Below Tm, increasing cholesterol increases D; a 10-fold increase occurs between 10 and 20 mol % at 21 degrees C, between 20 and 25 mol % at 15 degrees C, and between 25 and 30 mol % at 5 degrees C. In egg phosphatidylcholine (EPC) MBL, D decreases linearly from 5 X 10(-8) cm2/s at 35 degrees C to 2 X 10(-8) cm2/s at 5 degrees C; addition of equimolar cholesterol reduces D by a factor of 2. Thus this transmembrane polypeptide at low membrane concentrations diffuses quite like a lipid molecule. Its diffusivity in lipid mixtures appears to reflect predicted changes of lateral composition. Increasing gramicidin C (GC) in DMPC/GC MBL broadened the phase transition, and the diffusion coefficient of the lipid probe N-4-nitrobenzo-2-diazole phosphatidylethanolamine (NBD-PE) at 30 degrees C decreases from 8 X 10(-8) cm2/s below 5 mol % GC to 2 X 10(-8) cm2/s at 14 mol % GC; D for DGC similarly decreases from 4 X 10(-8) cm2/s at 2 mol % GC to 1.4 X 10(-8) cm2/s at 14 mol % GC. Hence, above Tm, high concentrations of this polypeptide restrict the lateral mobility of membrane components.
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U2 - 10.1016/S0006-3495(82)84467-6
DO - 10.1016/S0006-3495(82)84467-6
M3 - Article
C2 - 6184082
AN - SCOPUS:0020401953
VL - 40
SP - 129
EP - 135
JO - Biophysical Journal
JF - Biophysical Journal
SN - 0006-3495
IS - 2
ER -