[Resistance of various protein channels to proteolytic degradation]

The influence of some proteolytic enzymes on the properties of the ionic channels induced in the lipid bilayer by three different toxic proteins was studied. It was found that pronase and trypsin did not decrease the conductance of the membranes modified by melittin, alpha-staphylotoxin and latrotoxin and changed its cation-anion selectivity. The dependence of melittin-channels selectivity on the medium pH was investigated. It was suggested that the carbonyl groups of peptide bond take part in defining cation selectivity of the melittin channel.