Thermal stability of the secondary structure of poly(alpha,L-glutamate) in self-assembled complexes as studied by molecular dynamics in chloroform solution.

The thermal stability of the self-assembled complexes formed by alkyltrimethylammonium surfactants and poly(alpha,l-glutamate) is investigated in dilute chloroform solution by molecular dynamics simulations. By applying temperatures ranging from 300 to 500 K, we observed an extraordinary stability of the alpha-helix adopted by the polypeptide during a total of 48 ns. The multiple electrostatic interactions formed between the surfactant chains and the polyanion play a crucial role in this stability since they are responsible for the inaccessibility of the solvent molecules to the helix even at high temperatures.