OSCILLATION OF MEMBRANE-POTENTIAL IN CHEMICALLY-MODIFIED POLY(ALPHA-AMINO ACID) MEMBRANES

Chemically modified poly(gamma-methyl-L-glutamate) membranes having se veral lengths of diamine segments generated oscillation of membrane po tential under a concentration gradient of several salts, although nonm odified membranes showed constant potential. The oscillation of membra ne potential is considered to be caused by the fluctuation of the fixe d charge density originating from the thermal fluctuation of partially ionized amine segments in the modified membranes. The amplitude of th e oscillation was greater in the modified membranes having longer diam ine segments. It was also influenced by the salts used, and the highes t amplitude of the oscillation was observed when LiCl was used as the salt. Fast Fourier transport analysis revealed that the oscillation of membrane potential is not chaotic but has specific frequencies. It mi ght be possible to recognize a particular salt present in the solution from the information on the amplitude and the power spectrum of fast Fourier transport in the oscillation of membrane potential.