Massey J B
Biochim Biophys Acta. 1984 May 11;793(3):387-92. doi: 10.1016/0005-2760(84)90253-4.
The rate of spontaneous transfer of alpha-tocopherol, cholesterol and beta-carotene between model and native lipoproteins was measured to determine the mechanism and kinetics of equilibration of these lipids in plasma. Cholesterol and alpha-tocopherol transfer from apolipoprotein A-I/1-palmityl-2- oleoylphosphatidylcholine ( POPC ) recombinants to bovine brain ganglioside/ POPC single bilage vesicles with half-times of approximately 20 min and 70 min, respectively. Under identical conditions, there is no significant transfer of beta-carotene even after an 18-h incubation period. alpha-Tocopherol transfers from apolipoprotein A-II/dimyristoylphosphatidylcholine recombinants with a half-time of 40 min and an activation energy of 17.2 kcal/mol. Incubation of high-density lipoproteins containing alpha-[3H]tocopherol with low-density lipoproteins or very-low-density lipoproteins results in the equilibration of the labelled lipid between the lipoprotein classes in 1 h. A comparison of the rates of transfer indicates that alpha-tocopherol equilibrates 2-3-times more slowly than cholesterol but on a time scale much shorter than the lifetime of lipoproteins in the circulation. Thus, the distribution of alpha-tocopherol is not kinetically controlled but determined thermodynamically by the partitioning between the total amount of lipid in each compartment. The spontaneous transfer of beta-carotene is too slow for this equilibration to occur.
测定了α-生育酚、胆固醇和β-胡萝卜素在模型脂蛋白和天然脂蛋白之间的自发转移速率，以确定这些脂质在血浆中平衡的机制和动力学。胆固醇和α-生育酚从载脂蛋白A-I/1-棕榈酰-2-油酰磷脂酰胆碱（POPC）重组体转移至牛脑神经节苷脂/POPC单层囊泡，半衰期分别约为20分钟和70分钟。在相同条件下，即使经过18小时的孵育期，β-胡萝卜素也没有明显转移。α-生育酚从载脂蛋白A-II/二肉豆蔻酰磷脂酰胆碱重组体转移，半衰期为40分钟，活化能为17.2千卡/摩尔。将含有α-[3H]生育酚的高密度脂蛋白与低密度脂蛋白或极低密度脂蛋白一起孵育，1小时内标记脂质在脂蛋白类别之间达到平衡。转移速率的比较表明，α-生育酚达到平衡的速度比胆固醇慢2至3倍，但时间尺度比循环中脂蛋白的寿命短得多。因此，α-生育酚的分布不是由动力学控制的，而是由每个隔室中脂质总量之间的分配热力学决定的。β-胡萝卜素的自发转移太慢，无法发生这种平衡。
