Transport rate of various lipophilic ions through membranes of Halobacterium halobium

Abstract

Listen

Translate article

Abstract Various phosphonium cations have been used as probes for the membrane potential. The kinetics of the transport of phosphonium cations through the membrane of envelope vesicles of Halobacterium halobium were analysed. The phosphonium cations used were a homologous series of (Phe)3-P+ -(CH2)n-CH3 (n = 0–5) and tetraphenylphosphonium (TPP+). The order of magnitude of the kinetic constant of various phosphonium cations was approximately equal to that of the binding. The on-kinetic constant depends on the membrane potential generated and shows a minimum at −90 to −100 mV, while the off-kinetic constant is independent of the membrane potential which had been generated before the measurement.