Pressure effect on the rate of crystalline phase formation of L-alpha-dipalmitoylphosphatidylcholines in multilamellar dispersions.
Pressure effect on the rate of crystalline phase formation of L-alpha-dipalmitoylphosphatidylcholines in multilamellar dispersions.
复制标题
压力对多层分散体中 L-α-二棕榈酰磷脂酰胆碱结晶相形成速率的影响。
DOI：
10.1016/s0006-3495(85)83896-0
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发表时间：
1985
影响因子：
3.4
通讯作者：
Huang,CH
中科院分区：
文献类型：
--
作者：
Wu,WG;Chong,PL;Huang,CH
完全水合的二棕榈酰磷脂酰胆碱（DPPC）在多层分散体中经历结晶Lc相和凝胶L β相之间的亚转变。只有当DPPC-H2O系统在接近0 ℃的温度下孵育较长时间时，才会发生这种所谓的亚转变。我们已经研究了在0 ℃下，高达336个大气压的压力对多层DPPC分散体的结晶Lc相形成速率的影响。通过离心场产生流体静压;在环境压力下通过量热法监测多组分DPPC分散体中层状Lc相的形成。结果表明，随着压力的增加，水合结晶Lc相的形成速率降低。基于过渡态理论，通过压力形成水合结晶Lc相的延迟是由于当形成活化状态时脂质-水体系的体积增加。我们的解释是，积极的值的激活体积主要是由于脱水的脂质极性头基团。虽然酰基链有序化和头基脱水都与L β-Lc相变有关，但观察压力对结晶Lc相形成速率的影响表明，头基脱水在控制L β-Lc相变动力学中起主导作用。
Fully hydrated dipalmitoylphosphatidylcholine (DPPC) in multilamellar dispersions undergoes a subtransition between the crystalline Lc phase and the gel L beta phase. This so-called subtransition occurs only if the DPPC-H2O system has been incubated at temperatures near 0 degrees C for an extended period. We have examined the effect of pressure, up to 336 atm, on the rate of crystalline Lc phase formation of multilamellar DPPC dispersions at 0 degrees C. The hydrostatic pressure is generated by a centrifugal field; the formation of the lamellar Lc phase in the multicomponent DPPC dispersions is monitored calorimetrically at ambient pressure. Results indicate that the rate of formation of the hydrated crystalline Lc phase decreases with increasing pressure. Based on transition state theory, the retardation of the formation of the hydrated crystalline Lc phase by pressure is due to an increase in the volume of the lipid-water system when the activated state is formed. We interpret that the positive value of activation volume is attributed primarily to the dehydration of the lipid polar head group. Although the acyl chain ordering and the head group dehydration are both associated with the L beta----Lc phase transition, the observation of the pressure effects on the rate of crystalline Lc phase formation is used to show that the head group dehydration plays a predominant role in controlling the kinetics of the L beta----Lc phase transition.