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Polylysine decelerates kinetics of negatively charged gramicidin channels as shown by sensitized photoinactivation
Author(s) -
Krylov Andrey V,
Antonenko Yuri N,
Kotova Elena A,
Rokitskaya Tatiana I,
Yaroslavov Alexander A
Publication year - 1998
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(98)01462-8
Subject(s) - kinetics , gramicidin , chemistry , biophysics , polylysine , biochemistry , membrane , biology , physics , quantum mechanics
Effect of a cationic polymer, poly( l ‐lysine), on the kinetic properties of ionic channels formed by neutral gramicidin A (gA) and its negatively charged analogue O ‐pyromellitylgramicidin (OPg) in a bilayer lipid membrane is studied using a method of sensitized photoinactivation. This newly developed method is based on the analysis of transmembrane current transients induced by a flash in the presence of a photosensitizer. It has been shown previously that the time course of the flash‐induced current decrease in most cases follows a single exponential decay with an exponential factor (τ, the characteristic time of photoinactivation) that correlates well with the single‐channel lifetime. Addition of polylysine does not affect τ for gA channels, but causes a substantial increase in τ for OPg channels. This effect is reversed by addition of polyacrylic acid. The deceleration of the photoinactivation kinetics is ascribed to electrostatic interaction of polylysine with OPg probably resulting in OPg clustering. The latter can stabilize the channel state by reducing the rotational and lateral mobility of OPg monomers and dimers, and thus increase the single channel lifetime.