Ahmed M, Burton J S, Hadgraft J, Kellaway I W
J Membr Biol. 1981 Feb 28;58(3):181-9. doi: 10.1007/BF01870904.
The partitioning of nine phenothiazines between dimyristoylphosphatidylcholine (DMPC) liposomes and 0.9% wt/vol saline at pH 6 has been studied both below and above the phase transition temperature (Tc) of the phospholipid. Higher partitioning was observed above Tc. Both the entropy and enthalpy of partitioning were positive below and above Tc, and a linear relationship between the entropy and enthalpy has been derived. In general, the partitioning and transport of alkylaminophenothiazines in DMPC liposomes over the temperature range of 5 to 40 degrees C is entropically controlled. The entropies and enthalpies of partitioning of various groups in the phenothiazine structure have been calculated. No relationship was found between particle size of the DMPC liposomes and the equilibrium partition coefficient at 25 degrees C. However, the particle size of liposomes did increase with increasing acyl chain length of the phospholipid. Using differential scanning calorimetry, the enthalpy and entropy of transition of the DMPC liposomes in the absence and presence of phenothiazines has been calculated. The temperature dependence of the first-order rate constant of trimeprazine tartrate transport in DMPC liposomes was investigated and was found to be maximum at the Tc of the phospholipid.
已研究了九种吩噻嗪在二肉豆蔻酰磷脂酰胆碱（DMPC）脂质体与pH值为6的0.9%（重量/体积）盐溶液之间在磷脂相变温度（Tc）上下的分配情况。在Tc以上观察到更高的分配率。在Tc上下，分配的熵和焓均为正值，并且已得出熵与焓之间的线性关系。一般来说，在5至40摄氏度温度范围内，烷基氨基吩噻嗪在DMPC脂质体中的分配和转运受熵控制。已计算出吩噻嗪结构中各种基团的分配熵和焓。未发现DMPC脂质体的粒径与25摄氏度时的平衡分配系数之间存在关系。然而，脂质体的粒径确实随着磷脂酰基链长度的增加而增大。使用差示扫描量热法，已计算出在不存在和存在吩噻嗪的情况下DMPC脂质体转变的焓和熵。研究了酒石酸三甲丙嗪在DMPC脂质体中转运的一级速率常数对温度的依赖性，发现其在磷脂的Tc时最大。
