Awad Tarek S, Okamoto Yoshihide, Masum Shah Md, Yamazaki Masahito
Materials Science, Graduate School of Science and Engineering, Shizuoka University, Japan.
Langmuir. 2005 Dec 6;21(25):11556-61. doi: 10.1021/la051782i.
We developed a new method for the transformation of large unilamellar vesicles (LUVs) into the cubic phase. We found that the addition of low concentrations of Ca(2+) to suspensions of multilamellar vesicles (MLVs) of membranes of monoolein (MO) and dioleoylphosphatidylglycerol (DOPG) mixtures (DOPG/MO) changed their L(alpha) phase to the cubic phases. For instance, the addition of 15-25 mM Ca(2+) to 30%-DOPG/70%-MO-MLVs induced the Q(229) phase, whereas the addition of > or =28 mM Ca(2+) induced the Q(224) phase. LUVs of DOPG/MO membranes containing > or =25 mol % DOPG were prepared easily. Low concentrations of Ca(2+) transformed these LUVs in excess buffer into the Q(224) or the Q(229) phase, depending on the Ca(2+) concentration. For example, 15 and 50 mM Ca(2+) induced the Q(224) and Q(229) phase in the 30%-DOPG/70%-MO-LUVs at 25 degrees C, respectively. This finding is the first demonstration of transformation of LUVs of lipid membranes into the cubic phase under excess water condition.
我们开发了一种将大单层囊泡（LUVs）转变为立方相的新方法。我们发现，向单油酸甘油酯（MO）和二油酰磷脂酰甘油（DOPG）混合物（DOPG/MO）的多层囊泡（MLVs）悬浮液中添加低浓度的Ca(2+)会使其L(α)相转变为立方相。例如，向30%-DOPG/70%-MO-MLVs中添加15 - 25 mM Ca(2+)会诱导出Q(229)相，而添加≥28 mM Ca(2+)会诱导出Q(224)相。含有≥25 mol% DOPG的DOPG/MO膜的LUVs很容易制备。低浓度的Ca(2+)会将这些在过量缓冲液中的LUVs转变为Q(224)相或Q(229)相，这取决于Ca(2+)的浓度。例如，在25℃时，15 mM和50 mM Ca(2+)分别在30%-DOPG/70%-MO-LUVs中诱导出Q(224)相和Q(229)相。这一发现首次证明了在过量水条件下脂质膜的LUVs可转变为立方相。
