Groll R, Böttcher A, Jäger J, Holzwarth J F
Fritz-Haber-Institut der Max-Planck-Gesellschaft, D-14195 Berlin-Dahlem, Germany.
Biophys Chem. 1996 Jan 16;58(1-2):53-65. doi: 10.1016/0301-4622(95)00085-2.
The kinetics of the main phase transition of dimyristoylphosphatidyl choline (DMPC) unilamellar vesicles were investigated in the time range from microseconds to seconds. Iodine laser-temperature jump (ILTJ) experiments showed three discrete relaxation phenomena. Time resolved cryo-electron microscopy (CEM) was applied to produce images of intermediate states typical for the relaxation times of lipid vesicles in the micro- to millisecond time window. A careful measurement of the rate of temperature decrease observed during the production of vitrified lamellae of aqueous samples on a copper grid was performed. The best conditions resulted in average rates of cooling of 3 x 10(4) K/s. By comparing the images from CEM of DMPC vesicle samples vitrified above, at, and below the phase transition temperature a structural model was designed, which explains the temperature jump relaxation times in the micro- to millisecond time range by the formation and disappearance of coexisting clusters of crystalline, intermediate, and fluid lipid areas inside the DMPC bilayers.
在从微秒到秒的时间范围内，研究了二肉豆蔻酰磷脂酰胆碱（DMPC）单层囊泡主要相变的动力学。碘激光温度跃变（ILTJ）实验显示出三种离散的弛豫现象。应用时间分辨冷冻电子显微镜（CEM）来生成在微秒到毫秒时间窗口内脂质囊泡弛豫时间典型的中间状态图像。对在铜网上制备水性样品的玻璃化薄片过程中观察到的温度下降速率进行了仔细测量。最佳条件下的平均冷却速率为3×10⁴K/s。通过比较在高于、处于和低于相变温度下玻璃化的DMPC囊泡样品的CEM图像，设计了一个结构模型，该模型通过DMPC双层内共存的结晶、中间和流体脂质区域簇的形成和消失来解释微秒到毫秒时间范围内的温度跃变弛豫时间。
