磷脂囊泡的质子和氢氧根离子渗透性。
Proton and hydroxide ion permeability of phospholipid vesicles.
作者信息
Nozaki Y, Tanford C
出版信息
Proc Natl Acad Sci U S A. 1981 Jul;78(7):4324-8. doi: 10.1073/pnas.78.7.4324.
The apparent permeability of H+ through phospholipid bilayers was determined by measuring H+ efflux from large unilamellar phospholipid vesicles with internal space buffered at pH 4. The value obtained is about 10(-9) cm/sec at room temperature, five orders of magnitude lower than was recently reported for the combined permeability for H+ and OH- [Nichols, J. W. & Deamer, D. W. (1980) Proc. Natl. Acad. Sci. USA, 77, 2038-2042]. The apparent permeability measured in this way is the sum of contributions from the movement of H+ and of uncharged species (HCl or HNO3) in equilibrium with anions in the solution. There is evidence that the uncharged species make the dominant contribution and that the permeability coefficient for H+ per se is no larger than 5 X 10(-12) cm/sec. An attempt to measure OH- permeability by use of vesicles buffered at pH 10 did not give a conclusive result because the vesicle walls appeared to be damaged by exposure to this pH. An apparent permeability coefficient of about 10(-7) cm/sec was estimated for undamaged membranes.
通过测量内部空间pH值为4的大单层磷脂囊泡中H⁺的流出量，确定了H⁺通过磷脂双层的表观渗透率。在室温下获得的值约为10⁻⁹ cm/秒，比最近报道的H⁺和OH⁻的综合渗透率低五个数量级[Nichols, J. W. & Deamer, D. W. (1980) Proc. Natl. Acad. Sci. USA, 77, 2038 - 2042]。以这种方式测量的表观渗透率是H⁺移动以及与溶液中阴离子处于平衡状态的不带电物种（HCl或HNO₃）移动所做贡献的总和。有证据表明不带电物种起主要作用，且H⁺本身的渗透系数不大于5×10⁻¹² cm/秒。尝试通过使用pH值为10的缓冲囊泡来测量OH⁻渗透率，但未得出确凿结果，因为囊泡壁似乎因暴露于该pH值而受损。对于未受损的膜，估计表观渗透系数约为10⁻⁷ cm/秒。
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