Interrelation between hydration and interheadgroup interaction in phospholipids

被引:6
作者
Miller, IR
Bach, D
Wachtel, EJ
Eisenstein, M
机构
[1] Weizmann Inst Sci, Dept Biol Chem, IL-76100 Rehovot, Israel
[2] Weizmann Inst Sci, Dept Chem Serv, IL-76100 Rehovot, Israel
关键词
phospholipids; differential scanning calorimetry (DSC); FTIR modeling;
D O I
10.1016/S1567-5394(02)00035-X
中图分类号
Q5 [生物化学]; Q7 [分子生物学];
学科分类号
071010 ; 081704 ;
摘要
The stability and the ionic conductivity of biological membranes and of lipid bilayers depend on their hydration. A small number of water molecules adhere strongly to the different residues of the lipid headgroups and are oriented by them. An additional number of water molecules adhere more weakly, preserving their freedom of rotation, but are essential for bestowing the thermodynamic properties of hydrated bilayers and of biological membranes. Around six water molecules are attached so strongly to the headgroups of different phospholipids (PL) that they are rendered unfreezable, or their freezing is extended over such a wide range of temperatures that it cannot be detected by differential scanning calorimetry (DSC). If cholesterol is added to the PL above the concentration at which phase separation of the cholesterol phase occurs, the number of unfreezable water molecules per PL increases, indicating that the PL molecules on the border line between the two phases attach nearly twice as many water molecules as those in the middle of the phase. The orientation of about seven or eight water molecules attached to PL headgroups (seven to phosphatidyl serine (PS)) can be detected by polarized FTIR. The dichroic ratio of the successively adhering water molecules to the headgroup of PS fluctuates between 2.6 and 2.9, with the cumulative value of about 2.8 for the seven water molecules adhering to the headgroup of PS. In addition, in this case, the number of water molecules oriented by PL molecule residues on the border line of the two phases is much larger (similar to 13 for PS). Interaction between two opposite negatively charged layers containing PS approaching each other may lead, after correlated electrostatic attraction, to change in the conformation of the headgroups with concomitant dehydration. This process is enhanced by Ca+ and by Li+, but it may also occur with Na+ and K+ as counter-ions if the layers are mutually aligned. This process may be important in the fusion mechanism of biological membranes, and its molecular modeling has been carried out. (C) 2002 Published by Elsevier Science B.V.
引用
收藏
页码:193 / 196
页数:4
相关论文
共 8 条
[1]   COMPOSITIONAL ASPECTS OF LIPID HYDRATION [J].
BACH, D ;
SELA, B ;
MILLER, IR .
CHEMISTRY AND PHYSICS OF LIPIDS, 1982, 31 (04) :381-394
[2]   Hydration of phospholipid bilayers in the presence and absence of cholesterol [J].
Bach, D ;
Miller, IR .
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES, 1998, 1368 (02) :216-224
[3]   INFRARED STUDIES OF FULLY HYDRATED SATURATED PHOSPHATIDYLSERINE BILAYERS - EFFECT OF LI+ AND CA-2+ [J].
CASAL, HL ;
MANTSCH, HH ;
HAUSER, H .
BIOCHEMISTRY, 1987, 26 (14) :4408-4416
[4]   Determination of DMPC hydration in the L(alpha) and L(beta') phases by H-2 solid state NMR of D2O [J].
Faure, C ;
Bonakdar, L ;
Dufourc, EJ .
FEBS LETTERS, 1997, 405 (03) :263-266
[5]   Hydration of phosphatidyl serine multilayers and its modulation by conformational change induced by correlated electrostatic interaction [J].
Miller, IR ;
Bach, D .
BIOELECTROCHEMISTRY AND BIOENERGETICS, 1999, 48 (02) :361-367
[6]   Organization of water molecules by adhering to oriented layers of dipalmitoylphosphatidyl serine in the presence of varying concentrations of cholesterol [J].
Miller, IR ;
Bach, D .
BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES, 2000, 1468 (1-2) :199-202
[7]   Interbilayer interaction and deuterium-proton exchange in thin films of phosphatidyl serine [J].
Miller, IR ;
Wachtel, E .
BIOELECTROCHEMISTRY AND BIOENERGETICS, 1998, 45 (02) :203-214
[8]   Structure of phosphatidyl serine (PS) involved in interbilayer salt bridging and hydrogen bonding [J].
Miller, IR ;
Eisenstein, M .
BIOELECTROCHEMISTRY, 2000, 52 (01) :77-81