Matuoka S, Kato S, Hatta I
Department of Physics, School of Medicine, Sapporo Medical University, Japan.
Biophys J. 1994 Aug;67(2):728-36. doi: 10.1016/S0006-3495(94)80533-8.
The ripple structure was studied as a function of temperature in fully hydrated dimyristoylphosphatidylcholine (DMPC)/cholesterol multibilayers using synchrotron x-ray small-angle diffraction and freeze-fracture electron microscopy. In the presence of cholesterol, the ripple structure appears below the pretransition temperature of pure DMPC multibilayers. In this temperature range the ripple periodicity is relatively large (25-30 nm) and rapidly decreases with increasing temperature. In this region, defined as region I, we observed coexistence of the P beta' phase and the L beta' phase. The large ripple periodicity is caused by the formation of the P beta' phase region in which cholesterol is concentrated and the L beta' phase region from which cholesterol is excluded. An increase in ripple periodicity also takes place in the narrow temperature range just below the main transition temperature. We define this temperature region as region III, where the ripple periodicity increases dramatically toward the main transition temperature. In region II, between regions I and III, the ripple periodicity decreases gradually with temperature. This behavior is quite similar to that of pure DMPC. Temperature-versus-ripple periodicity curves are parallel among pure DMPC and DMPCs with various cholesterol contents. We explain this behavior in terms of a model proposed by other workers.
利用同步加速器X射线小角衍射和冷冻蚀刻电子显微镜，研究了完全水合的二肉豆蔻酰磷脂酰胆碱（DMPC）/胆固醇多层膜中波纹结构随温度的变化。在存在胆固醇的情况下，波纹结构出现在纯DMPC多层膜的预转变温度以下。在此温度范围内，波纹周期相对较大（25 - 30纳米），并随温度升高而迅速减小。在这个定义为区域I的区域，我们观察到Pβ'相和Lβ'相共存。大的波纹周期是由胆固醇集中的Pβ'相区域和胆固醇被排除的Lβ'相区域的形成引起的。在刚好低于主转变温度的狭窄温度范围内，波纹周期也会增加。我们将这个温度区域定义为区域III，在该区域波纹周期朝着主转变温度急剧增加。在区域I和III之间的区域II中，波纹周期随温度逐渐减小。这种行为与纯DMPC的行为非常相似。纯DMPC和具有不同胆固醇含量的DMPC之间的温度与波纹周期曲线是平行的。我们根据其他研究者提出的模型来解释这种行为。
