Protein-like copolymers: Computer simulation

The model ofAB copolymers with a “protein-like” primary sequence was developed. This type of copolymers was obtained in a computer experiment. First, the conformation of a collapsed dense homopolymer globule was generated and then, based on this conformation, the primaryAB sequence was determied by denoting the monomeric units located near the surface of the globule as unitsA and those constituting the core of the globule as unitsB. After that, the primary structure of the chain was fixed, and different interaction potentials for theA andB units were introduced. Drawing an analogy of this model to aqueous solutions of globular proteins,A units were interpreted as hydrophilic, andB units were regarded as hydrophobic. By means of Monte Carlo simulation using the bond fluctuation model, the coli—globule transition in “protein-like”AB copolymer, induced by an increase in the attraction between the hydrophobicB units, was studied. The coil—globule transition in a copolymer with the “protein-like” primary sequence occurs at a higher temperature and has higher rate and is sharper than that in a random copolymer with the sameA/B composition and in a random block copolymer with the sameA/B composition and the same “degree of blockiness”.