Chrzeszczyk A, Wishnia A, Springer C S
Biochim Biophys Acta. 1977 Oct 17;470(2):161-9. doi: 10.1016/0005-2736(77)90097-9.
Phosphorus-31 NMR studies of solutions of small L-alpha-dipalmitoyl phosphatidylcholine bilayer vesicles containing sodium dimethyl phosphate uniformly distributed between the continuous external and the intravesicular aqueous spaces, with the paramagnetic shift reagent Pr3+ present only in the external space, are reported. These studies give the distribution both of dipalmitoyl phosphatidylcholine in the vesicle inner and outer monolayers and of dimethyl phosphate in the aqueous spaces. With the third necessary parameter obtained from the vesicle sedimentation coefficient, the very different packing parameters of dipalmitoyl phosphatidylcholine in inner and outer monolayers can be determined. The vesicle outer radius is 109 A. Although the total bilayer thickness is virtually identical to that of planar bilayers, the outer monolayer is thicker (20 A) and the inner monolayer thinner (15 A). The area per head group at the inner surface, 68 A2, is like the planar value, but the tails are much more folded, so as to decrease the radial lengths and increase the tangential spreat (to 94A2). The reverse is true in the outer layer: the surface per head group is 76 A2, tapering to 51 A2 in the tail region, so that outer layer tails are relatively extended. The difference is equivalent to a shift of about two 2g1 kinks from outer to inner layers; the uneven packing certainly affects fluidity, and may have important biological consequences.
报道了对小的L-α-二棕榈酰磷脂酰胆碱双层囊泡溶液的磷-31核磁共振研究，其中磷酸二甲钠均匀分布在连续的外部和囊泡内水相中，顺磁位移试剂Pr3+仅存在于外部空间。这些研究给出了二棕榈酰磷脂酰胆碱在囊泡内、外单层中的分布以及磷酸二甲酯在水相中的分布。利用从囊泡沉降系数获得的第三个必要参数，可以确定二棕榈酰磷脂酰胆碱在内、外单层中非常不同的堆积参数。囊泡外半径为109埃。尽管双层总厚度实际上与平面双层相同，但外层单层更厚（20埃），内层单层更薄（15埃）。内表面每个头部基团的面积为68埃2，与平面值相似，但尾部折叠得更多，从而减小了径向长度并增加了切向扩展（至94埃2）。外层情况相反：每个头部基团的表面积为76埃2，在尾部区域逐渐减小至51埃2，因此外层尾部相对伸展。这种差异相当于约两个2g1扭结从外层向内层的转移；不均匀的堆积肯定会影响流动性，并且可能具有重要的生物学后果。
