Coronado R
Biophys J. 1985 Jun;47(6):851-7. doi: 10.1016/S0006-3495(85)83990-4.
Monolayers of the negatively charged phospholipid phosphatidylserine (PS) and of the amphoteric phospholipid dioleoylphosphatidylethanolamine (DOPE) were used to assemble bilayers at the tip of patch-recording pipettes. PS bilayers, with seal resistances in the range of gigaohmns (gigaseals), could only be generated when millimolar concentration of divalent cations, Ca++, Mg++, or Ba++ were present in the pipette and bath solutions. In contrast, gigaseals of DOPE were independent of divalent ion concentration in the pH range where DOPE is predominantly neutral (pH 6.5) or positively charged (pH 1.5). At pH 10.0, when most DOPE molecules bear a net negative charge, gigaseals became divalent cation dependent, in a manner quantitatively similar to that of PS at neutral pH. The results indicate that divalent cations play an important role in stabilizing gigaseals of negatively charged lipid but are of no consequence in neutral or positively charged seals.
带负电荷的磷脂酰丝氨酸（PS）单层和两性磷脂二油酰磷脂酰乙醇胺（DOPE）单层被用于在膜片钳记录电极尖端组装双层膜。只有当移液管和浴槽溶液中存在毫摩尔浓度的二价阳离子Ca++、Mg++或Ba++时，才能产生具有千兆欧电阻（千兆封接）范围的PS双层膜。相比之下，在DOPE主要呈中性（pH 6.5）或带正电荷（pH 1.5）的pH范围内，DOPE的千兆封接与二价离子浓度无关。在pH 10.0时，当大多数DOPE分子带有净负电荷时，千兆封接变得依赖于二价阳离子，其方式在数量上与中性pH下的PS相似。结果表明，二价阳离子在稳定带负电荷脂质的千兆封接中起重要作用，但在中性或带正电荷的封接中则无关紧要。
