Competitive Reactions in Solutions of Protein-Polyelectrolyte Complexes

摘要

The ability of negatively charged globular proteins (bovine serum albumin, trypsin soy inhibitor) to interact with linear synthetic polycations (poly-N-ethyl-4-vinylpyridinium bromide, poly-N,N-dimethyldiallylammonium chloride) and to form negatively charged water-soluble complexes, in which the protein is a lyophilizing component has been revealed. The complexes are formed if the total number of the protein negative charges exceeds the total number of the polycation positive charges in the mixture. The composition of the complexes remains virtually unchanged and corresponds to one chain of polycation and only such number of protein globules that provides the solubility of the complex particle as a whole. The competitive reaction accompanied with transfer of the protein globule from one complex species to another one was studied by fluorescence quenching technique. It is shown that the rate of the reaction is quite high even in dilute aqueous solution and becomes higher after addition of salt (NaCl). As it follows from the results obtained these model systems obey the basic principles established for interpolyelectrolyte reactions in solutions of oppositely charged flexible-chain synthetic polyions.