Garcia M L, Kitada M, Eisenstein H C, Krulwich T A
Biochim Biophys Acta. 1984 Jul 27;766(1):109-15. doi: 10.1016/0005-2728(84)90222-6.
Liposomes containing buffered KCl were prepared from bacterial lipids, were diluted into K+-free media and were treated with valinomycin to induce the formation of a diffusion potential (delta psi). Upon formation of such a potential, substantial proton influx was observed, as assayed by the quenching of 9-aminoacridine fluorescence. Complete reversal of fluorescence quenching occurred when the potential was collapsed by addition of KCl or when methylamine was added. Studies of proton influx as a function of the theoretical magnitude of the delta psi indicated that the phenomenon occurred only above a delta psi of about -60 mV. Establishment of a Na+ diffusion potential also resulted in proton influx. Treatment of K+-loaded liposomes with N,N'-dicyclohexylcarbodiimide did not reduce the delta psi-dependent proton influx. Moreover, proton influx could be demonstrated upon imposition of a diffusion potential in liposomes prepared from a synthetic lipid. The proton fluxes associated with generation of a diffusion potential in liposomes may complicate studies of reconstituted systems in which proton translocation should occur, and may affect the magnitude of the electrochemical proton gradient that is operant under some conditions.
含有缓冲氯化钾的脂质体由细菌脂质制备而成，被稀释到无钾培养基中，并用缬氨霉素处理以诱导扩散电位（δψ）的形成。在形成这种电位时，观察到大量质子内流，这通过9-氨基吖啶荧光猝灭来测定。当通过添加氯化钾使电位消失或添加甲胺时，荧光猝灭完全逆转。对质子内流作为δψ理论大小的函数的研究表明，该现象仅在约-60 mV的δψ以上发生。建立钠扩散电位也会导致质子内流。用N，N'-二环己基碳二亚胺处理负载钾的脂质体不会降低依赖于δψ的质子内流。此外，在由合成脂质制备的脂质体中施加扩散电位时可以证明质子内流。与脂质体中扩散电位产生相关的质子通量可能会使其中应发生质子转运的重组系统的研究复杂化，并可能影响在某些条件下起作用的电化学质子梯度的大小。
