Silvius J R, Read B D, McElhaney R N
Biochim Biophys Acta. 1979 Jul 19;555(1):175-8. doi: 10.1016/0005-2736(79)90081-6.
Diacyl phosphatidylcholines with n-C13, -C15, -C17 and -C19 saturated acyl chains have been synthesized and their phase transitions in the presence of excess water monitored by differential thermal analysis. The C15-, C17- and C19-diacyl species show gel to liquid-crystalline transitions and pretransitions like those of the even-chain phosphatidylcholines. A plot of the main phase transition temperature, Tc, vs. acyl chain length is a smooth curve on which the Tc values of both odd- and even-chain species fall, while a similar plot for the pretransition temperature, Tp, shows significant alternation of Tp between odd- and even-chain species. Consideration of these results in terms of the physical basis of the odd-even alternation of phase transition temperatures in homologous series of paraffinic compounds suggests that the acyl chains of disaturated phosphatidylcholines are tilted with respect to the bilayer normal below Tp but become perpendicular to the bilayer surface above the pretransition temperature.
已合成了具有正十三烷、正十五烷、正十七烷和正十九烷饱和酰基链的二酰基磷脂酰胆碱，并通过差示热分析监测了它们在过量水存在下的相变。C15 -、C17 -和C19 -二酰基物种显示出凝胶到液晶的转变以及预转变，类似于偶数链磷脂酰胆碱的转变。主相变温度Tc与酰基链长度的关系图是一条平滑曲线，奇数链和偶数链物种的Tc值都落在该曲线上，而预转变温度Tp的类似关系图显示奇数链和偶数链物种之间的Tp有显著交替。根据链烷烃同系物中相变温度奇偶交替的物理基础来考虑这些结果，表明二饱和磷脂酰胆碱的酰基链在Tp以下相对于双层法线倾斜，但在预转变温度以上变得垂直于双层表面。
