Phospholipids containing nitrogen- and sulfur-linked chains: kinetics of cholesterol exchange between vesicles.
Phospholipids containing nitrogen- and sulfur-linked chains: kinetics of cholesterol exchange between vesicles.
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含有氮和硫连接链的磷脂：囊泡之间胆固醇交换的动力学。
DOI：
10.1016/0005-2736(91)90256-8
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
Hajdu,J
中科院分区：
文献类型：
--
作者：
Kan,CC;Bittman,R;Hajdu,J
我们研究了以下合成甘油磷脂酰胆碱形成的单层囊泡之间[14C]胆固醇交换的动力学：(a)在n-2位置具有酰基（OC(O)R）、酰基（NHC(O)R）、氨基（NHC(O)OR）和酰基硫（SC(O)R）链的囊泡，以及(b)在n-1位置具有烷基（OR）和硫代烷基（SR）链的囊泡。用NH基团取代PC的n-2位置的甘油氧原子并不会在很大程度上影响胆固醇的交换速率，这表明鞘磷脂的酰胺基团不是鞘磷脂囊泡中观察到的胆固醇交换速率非常慢的主要原因。磷脂酰胆碱n-2位置的甘油氧被硫原子取代，导致自发胆固醇交换率增加了1.6倍。用巯基取代2-酰基硫代磷脂酰胆碱n-1位的酰基链或用巯基取代1-烷基-2-酰基氨基脱氧磷脂酰胆碱的o -烷基-1链也不会导致胆固醇交换率的显著差异。数据表明，除分子间氢键外，其他相互作用也参与了膜间胆固醇交换速率的决定。值得注意的是，这些动力学研究也支持了硫代和氮代磷脂酰胆碱模型膜的继续使用，这些模型膜已被用于研究脂溶酶的特性，因为合成的酰基氨基和酰基硫代磷脂形成囊泡，其胆固醇交换率与用二酯磷脂酰胆碱制备的囊泡非常相似。
We have examined the kinetics of [14C]cholesterol exchange between unilamellar vesicles formed from the following synthetic glycerophosphatidylcholines: (a) those having acyl (OC(O)R), acylamino (NHC(O)R), carbamoyl (NHC(O)OR), and acylthio (SC(O)R) chains at thesn-2 position, and (b) those having alkyl (OR) and thioalkyl (SR) chains at thesn-1 position. Replacement of the glycerol oxygen atom at thesn-2 position of PC with a NH group did not affect the rate of cholesterol exchange to a significant extent, suggesting that the amide group of sphingomyelin is not primarily responsible for the very slow rate of exchange of cholesterol observed from sphingomyelin vesicles. Replacement of the glycerol oxygen at thesn-2 position of phosphatidylcholine with a sulfur atom caused the rate of spontaneous cholesterol exchange to increase by a factor of 1.6. Substitution of anO-alkyl chain for the acyl chain at thesn-1 position of 2-acylthiophosphatidylcholine or substitution of a thioalkyl chain for theO-alkylsn-1 chain of 1-alkyl-2-acylaminodeoxyphosphatidylcholine also did not result in a marked difference in cholesterol exchange rate. The data suggest that interactions other than intermolecular hydrogen bonding are involved in determining the rates of intermembrane cholesterol exchange. Significantly, these kinetic studies also lend support to the continued use in model membranes of synthetic sulfur- and nitrogen-substituted phosphatidylcholines, which have been employed to study properties of lipolytic enzymes, since synthetic acylamino- and acylthio-phospholipids form vesicles that give cholesterol exchange rates that closely resemble those found in vesicles prepared with diester-phosphatidylcholines.