TY - JOUR
T1 - Detection of phase separation in fluid phosphatidylserine/phosphatidylcholine mixtures
AU - Hinderliter, A. K.
AU - Huang, J.
AU - Feigenson, G. W.
N1 - Funding Information:
We wish to thank Joe Navaie for help with the x-ray diffraction measure- ments at CHESS, Andy Dibble for help with the 31PNMR experiments, and Marian Szebenyi for help with the densitometer and for providing the plot- ting programs. This work was supported by National Institutes of Health grant HL-18255. A.K.H. was supported in part by NIH grant 1-T32-GM08267.
PY - 1994
Y1 - 1994
N2 - The nonideal mixing of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine, (16:0, 18:1)PS, and 1,2-didodecenoyl-sn-glycero-3-phosphocholine, (12:1, 12:1)PC, in fluid lamellar model membranes was studied by measuring binding of aqueous Ca2+ ions and by x-ray diffraction. A region of two-phase coexistence was found by invariance of the aqueous concentration and by the appearance of two sets of lamellar spacings. The phases were identified as fluid from the diffuse x-ray diffraction in the wide-angle region. The width of the two-phase coexistence region was greater at higher ionic strength. In 800 mM KCl, the phase boundaries were at PS mole fraction 0.5 and 0.8. In 100 mM KCl, the phase boundaries were at PS mole fraction 0.52 and 0.62. Monte Carlo simulations of the lateral distributions of these PS/PC mixtures show pronounced clustering of the lipids.
AB - The nonideal mixing of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphoserine, (16:0, 18:1)PS, and 1,2-didodecenoyl-sn-glycero-3-phosphocholine, (12:1, 12:1)PC, in fluid lamellar model membranes was studied by measuring binding of aqueous Ca2+ ions and by x-ray diffraction. A region of two-phase coexistence was found by invariance of the aqueous concentration and by the appearance of two sets of lamellar spacings. The phases were identified as fluid from the diffuse x-ray diffraction in the wide-angle region. The width of the two-phase coexistence region was greater at higher ionic strength. In 800 mM KCl, the phase boundaries were at PS mole fraction 0.5 and 0.8. In 100 mM KCl, the phase boundaries were at PS mole fraction 0.52 and 0.62. Monte Carlo simulations of the lateral distributions of these PS/PC mixtures show pronounced clustering of the lipids.
UR - http://www.scopus.com/inward/record.url?scp=0028077246&partnerID=8YFLogxK
U2 - 10.1016/S0006-3495(94)80673-3
DO - 10.1016/S0006-3495(94)80673-3
M3 - Article
C2 - 7858127
AN - SCOPUS:0028077246
SN - 0006-3495
VL - 67
SP - 1906
EP - 1911
JO - Biophysical Journal
JF - Biophysical Journal
IS - 5
ER -