Massari S, Arslan P, Nicolussi A, Colonna R
Biochim Biophys Acta. 1980 Jun 20;599(1):118-26. doi: 10.1016/0005-2736(80)90061-9.
Size enlargement of dipalmitoyl phosphatidylcholine vesicles was greatly accelerated in the range of the phase-transition temperatures, when fatty acid concentration was above a threshold level ('critical' concentration). This 'critical' concentration varied with the length of the fatty acid chain. The size enlargement process had second-order kinetics dependent on the vesicle concentration. Alkaline pH and low ionic strength inhibited the rate of size enlargement. Phospholipid exchange between dimyristoyl and dipalmitoyl phosphatidyl-choline vesicles increased abruptly above a 'critical' fatty acid concentration. The donor vesicles were those vesicles in which fatty acids reached the 'critical' concentration. The phospholipid exchange occurred both in fluid- and in solidstate vesicles. The 'critical' fatty acid concentration accelerating the phospholipid exchange process was lower than that accelerating the size enlargement process. The phospholipid exchange process explained in terms of a diminished hydrophobic attraction among the phospholipid molecules of the bilayer occurs via a free phospholipid molecule transfer through the aqueous phase. The size enlargement process is interpreted in terms of high fatty acid concentration in the membrane fluid domains. The membrane structure is locally perturbed inducing vesicle sticking after collision.
当脂肪酸浓度高于阈值水平（“临界”浓度）时，在相变温度范围内，二棕榈酰磷脂酰胆碱囊泡的尺寸增大速度大大加快。这种“临界”浓度随脂肪酸链的长度而变化。尺寸增大过程具有依赖于囊泡浓度的二级动力学。碱性pH值和低离子强度会抑制尺寸增大的速率。在高于“临界”脂肪酸浓度时，二肉豆蔻酰磷脂酰胆碱囊泡和二棕榈酰磷脂酰胆碱囊泡之间的磷脂交换会突然增加。供体囊泡是脂肪酸达到“临界”浓度的那些囊泡。磷脂交换在液态和固态囊泡中均会发生。加速磷脂交换过程的“临界”脂肪酸浓度低于加速尺寸增大过程的浓度。磷脂交换过程是通过游离磷脂分子在水相中的转移来解释的，这是由于双层磷脂分子之间的疏水吸引力减弱所致。尺寸增大过程是根据膜流体区域中高脂肪酸浓度来解释的。膜结构受到局部扰动，导致碰撞后囊泡粘连。
