Correa-Freire M C, Barenholz Y, Thompson T E
Biochemistry. 1982 Mar 16;21(6):1244-8. doi: 10.1021/bi00535a021.
We have studied the kinetics of transfer of glucocerebroside between phospholipid bilayers by using pyrene and 3H-labeled glucocerebroside incorporated into dimyristoylphosphatidylcholine (DMPC) and dipalmitoylphosphatidylcholine (DPPC) bilayers. Pyrene-labeled glucocerebroside (PyrCer) molecules are able to form an excited complex (eximer, E) between a PyrCer in the ground state and an excited monomer (M). When vesicles contained a known amount of PyrCer (donors) are incubated with unlabeled vesicles (acceptors), transfer of PyrCer from donor to acceptor populations is reflected in a decrease of the observed E/M intensity ratio. The results obtained from these studies show that the half-time of transfer from donor DMPC-PyrCer vesicles to acceptor DMPC vesicles is greater than 30 days at 37 degrees C. This very slow transfer of glucocerebroside was confirmed by using tritiated glucocerebroside incorporated into small unilamellar DPPC donor vesicles incubated with large unilamellar DPPC acceptor vesicles above the phase transition. Separation of the two vesicle populations by molecular sieve chromatography at 45 degrees C shows a half-time for transfer of approximately 32 days. We conclude that, in contrast to the results obtained for phosphatidylcholines [Roseman, M., & Thompson, T. E. (1980) Biochemistry 19, 439], glucocerebroside does not rapidly transfer between bilayers under these conditions.
我们通过将芘和3H标记的葡萄糖脑苷脂掺入二肉豆蔻酰磷脂酰胆碱（DMPC）和二棕榈酰磷脂酰胆碱（DPPC）双层膜中，研究了葡萄糖脑苷脂在磷脂双层膜之间的转移动力学。芘标记的葡萄糖脑苷脂（PyrCer）分子能够在基态的PyrCer和激发态单体（M）之间形成激发复合物（准分子，E）。当含有已知量PyrCer的囊泡（供体）与未标记的囊泡（受体）一起孵育时，PyrCer从供体群体向受体群体的转移反映在观察到的E/M强度比的降低上。这些研究获得的结果表明，在37℃下，从供体DMPC-PyrCer囊泡向受体DMPC囊泡转移的半衰期大于30天。通过使用掺入小单层DPPC供体囊泡中的氚化葡萄糖脑苷脂与高于相变温度的大单层DPPC受体囊泡一起孵育，证实了葡萄糖脑苷脂这种非常缓慢的转移。在45℃下通过分子筛色谱法分离这两个囊泡群体，显示转移的半衰期约为32天。我们得出结论，与磷脂酰胆碱的结果[罗斯曼，M.，&汤普森，T.E.（1980年）《生物化学》19卷，439页]相反，在这些条件下葡萄糖脑苷脂不会在双层膜之间快速转移。
