Polyampholytes with Various Charge Distributions: Conformation States via Computer Simulation

Abstract

By means of molecular dynamics computer simulation, the conformational space of polyampholyte macromolecules with various distributions of the charged groups along the chain is studied. A coarse-grained model where each monomer unit of the chain is presented as a non-charged group in the backbone of the macromolecule connected with a charged side pendant is considered. A limiting case of fully charged chains in the isoelectric point is investigated. The oppositely charged monomer units are distributed in various patterns: regular alternating, multiblock, or random sequences. It is found that the chains with random unit distribution adopt much more compacted conformations than the chains with regular distributions with comparable block lengths. Calculating the chain size and its fluctuation along with the spatial density distribution, coil, and globular conformations are distinguished and arranged on the diagrams in terms of chain length, block length, and Bjerrum length.

Keywords: charge sequences; computer simulations; conformational diagrams; polyampholytes.