Ionophoric material derived from eel membrane preparations
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- Blumenthal, R. & Shamoo, A.E. J. Membrain Biol. (1974) 19: 141. doi:10.1007/BF01869975
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Ionophoric material isolated by tryptic digestion of (Na++K+)-ATPase containing electroplax membranes shows fluctuating discrete current levels in oxidized cholesterol membranes with conductance amplitudes ranging from 10−10 to 10−9 mhos, suggesting pore formation. The rate of pore formation is dependent on the imposed voltage. If the voltage is maintained for a short time (5 to 10 sec), pore formation is reversible, whereas permanent pores are formed when the voltage is maintained for more than 10 sec. At pH=7 the permeability ratio for sodium versus chloride is 5 and for potassium versus sodium, 1.7. The permeability of the ionophoric material is dependent on pH. At pH=6 a conversion takes place from more cation-permeable to more anionpermeable pores, suggesting that histidine plays a role in the permeation mechanism. A model is proposed to account for the observed ionophoric properties.