Blaustein R O, Finkelstein A
Department of Physiology & Biophysics, Albert Einstein College of Medicine, Bronx, NY 10461.
Biochim Biophys Acta. 1988 Dec 22;946(2):221-6. doi: 10.1016/0005-2736(88)90396-3.
Although a number of molecules are known to function as current-carrying proton carriers across lipid bilayer membranes, no such hydroxide ion carriers have been found to date. We report that (C6F5)2Hg, which can function as a chloride ion carrier, can also carry a hydroxide ion. In 100 mM Na2SO4 solutions, membranes treated with (C6F5)2Hg are almost ideally selective for H+/OH- between pH 6.0 and 9.5. Membrane conductance varies linearly with [OH-] over this pH range and with the square of the (C6F5)2Hg concentration. The presumed current-carrying species is the dimer [(C6F5)2Hg]2OH-, which, along with the neutral molecule (C6F5)2Hg, shuttles back and forth within the bilayer. In 0.2 M NaCl at pH 9.5, the OH- and Cl- conductances are approximately equal. Thus, the carrier displays an approximately 10(4)-fold preference for OH- over Cl-.
虽然已知有多种分子可作为跨脂质双分子层膜的载流质子载体，但迄今为止尚未发现此类氢氧根离子载体。我们报告称，可作为氯离子载体的（C6F5）2Hg也能携带氢氧根离子。在100 mM Na2SO4溶液中，用（C6F5）2Hg处理过的膜在pH 6.0至9.5之间对H+/OH-几乎具有理想的选择性。在此pH范围内，膜电导随[OH-]呈线性变化，并随（C6F5）2Hg浓度的平方而变化。推测的载流物种是二聚体[（C6F5）2Hg]2OH-，它与中性分子（C6F5）2Hg一起在双分子层内来回穿梭。在pH 9.5的0.2 M NaCl中，OH-和Cl-的电导大致相等。因此，该载体对OH-的偏好比对Cl-约高10^4倍。
