Transfer of long-chain fluorescent free fatty acids between unilamellar vesicles.
Transfer of long-chain fluorescent free fatty acids between unilamellar vesicles.
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单层囊泡之间长链荧光游离脂肪酸的转移。
DOI：
10.1021/bi00355a041
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发表时间：
1986
期刊：
影响因子：
2.9
通讯作者：
A. Kleinfeld
中科院分区：
文献类型：
--
作者：
J. Storch;A. Kleinfeld
通过测定N-(9-氧代氧基)标记的荧光类似物(AOffA)在供体和受体囊泡之间的转移，研究了游离脂肪酸(FFA)在小单层囊泡(SUV)之间的迁移。供体为负载1~2mol%N-(7-nitro-2，1，3-benzoxadiazol-4-yl)phosphatidylethanolamine的卵磷脂酰胆碱(PC)，受体为含10~12mol%Aoffa的卵磷脂(NbD-PE)。直接加入到受体SUV中的AO的荧光强度大于98%，通过能量传递猝灭到NBD。因此，Aoffa从供体到受体的运动是通过依赖于时间的AO荧光减弱来监测的。短链Aoffa的转移虽然太快，不能用这里使用的方法来解决，但与发现转移速率在毫秒数量级和动力学为一级的研究是一致的。相比之下，长链AOffa的转移速率要慢2个数量级以上，转移过程的动力学最好用两个指数加一个常数的和来描述。FFA电离态也是转移速率的重要决定因素。带电物种的转移平均比质子化的FFA快10倍。膜中游离脂肪酸的pKa为9，由转移液的pH依赖性计算得出。与其他脂类的研究结果相似，长链Aoffa通过水转移，而不是通过碰撞介导的过程。Aoffa膜间转移的水相途径表明，供体和受体磷脂浓度的较大变化对转移没有影响。此外，随着[氯化钠]从0.1M增加到4M，转移速率降低。这种离子强度的影响可能不仅是由于Aoffa在水相中分配的减少，也是由于由1，6-二苯基-1，3，5-己三烯的荧光偏振测定的双层结构的改变。观察到的动力学符合一个模型，在该模型中，转移包括两个步骤：内外双层小叶之间的跨双层运动，然后从外部小叶转移到水相(OFF率)。在这个模型的框架内，观察到的慢速率主要由跨双分子层运动的速率决定，而观测到的快速率近似等于OFF速率。关闭速率大约是跨双分子层运动速率的10倍。
Movement of free fatty acids (ffa) between small unilamellar vesicles (SUV) was studied by measuring the transfer of fluorescent n-(9-anthroyloxy)-labeled analogues (AOffa) between donor and acceptor vesicles. Donors were composed of egg phosphatidylcholine (PC) loaded with 1-2 mol % AOffa, and acceptors were egg PC containing 10-12 mol % N-(7-nitro-2,1,3-benzoxadiazol-4-yl)phosphatidylethanolamine (NBD-PE). The fluorescence of AO added directly to acceptor SUV was greater than 98% quenched by energy transfer to NBD. Thus, AOffa movement from donor to acceptor was monitored by the time-dependent decrease in AO fluorescence. The transfer of the short-chain AOffa, although too fast to be resolved by the methods used here, is consistent with studies that find transfer rates on the order of milliseconds and kinetics which are first order. In contrast, transfer rates for the long-chain AOffa are more than 2 orders of magnitude slower, and the kinetics of the transfer process are best described by the sum of two exponentials plus a constant. The ffa ionization state was also found to be an important determinant of transfer rate. The charged species transferred an average of 10-fold faster than the protonated ffa. The ffa pKa in the membrane is 9, as calculated from the pH dependence of transfer. Similar to results found for other lipids, long-chain AOffa are transferred via water rather than a collision-mediated process. The aqueous phase route of AOffa intermembrane transfer is indicated by the lack of effect on transfer of large alterations in the product of donor and acceptor phospholipid concentrations. Moreover, the transfer rate is decreased as [NaCl] is increased from 0.1 to 4 M. This effect of ionic strength is probably due not only to a decrease in the aqueous phase partition of the AOffa but also to an alteration in bilayer structure, as measured by fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene. The observed kinetics are consistent with a model in which the transfer involves two steps: transbilayer movement between the inner and outer bilayer leaflets, followed by transfer from the outer leaflet to the aqueous phase (off rate). Within the framework of this model, the observed slow rate is primarily determined by the rate of transbilayer movement, and the observed fast rate is approximately equal to the off rate. The off rate is about 10-fold faster than the rate of transbilayer movement.
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DOI：
--
发表时间：
1985-01
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
R. Sleight;R. Pagano
通讯作者：
R. Sleight;R. Pagano
钙在体外改变大鼠肝细胞质膜的酰基链组成和脂质流动性。
DOI：
10.1016/0005-2736(85)90322-0
发表时间：
1985
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
Storch,J;Schachter,D
通讯作者：
Schachter,D
DOI：
10.1016/s0021-9258(17)47247-4
发表时间：
1984-07
期刊：
The Journal of biological chemistry
影响因子：
--
作者：
N. Abumrad;Jane H. Park;Charles R. Park
通讯作者：
N. Abumrad;Jane H. Park;Charles R. Park
胆固醇从小和大的单层囊泡转移。
DOI：
10.1016/0005-2736(84)90246-3
发表时间：
1984
期刊：
Biochimica et biophysica acta
影响因子：
--
作者：
McLean,LR;Phillips,MC
通讯作者：
Phillips,MC