Protein-polyelectrolyte complexes: Molecular dynamics simulations and experimental study

Publication date: 24 March 2017
Source:Polymer, Volume 113
Author(s): Alina A. Sofronova, Diana B. Evstafyeva, Vladimir A. Izumrudov, Vladimir I. Muronetz, Pavel I. Semenyuk
Despite use of polyelectrolytes is considered to be a prospective approach of protein aggregation suppression, owing to formation of soluble protein-polyelectrolyte complexes, the structure of the complexes and mechanism of their formation are not sufficiently understood. The aim of this work was to study the influence of degree of polymerization on the structure and properties of formed complexes. We carried out molecular dynamics simulations of complexes of cationic protein lysozyme with highly charged polyanions – poly(styrene sulfonate) and polyphosphate – of different degree of polymerization. It has been shown that the short charged chains are bound with the protein via a great majority of repeat units, while the long chains have unbound fragments that form charged loops and tails around the protein surface. These loops were earlier suggested to provide stability of the complex. Furthermore, the charge of the complex increased with increasing length of chain. These findings are consistent with the experimentally measured zeta potential. The obtained results help to explain why polyanion protective efficiency against protein aggregation increases with increase of the degree of polymerization.

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