Crowding effects on the structural transitions in a flexible helical homopolymer.

We elucidate the structural transitions in a helical off-lattice homopolymer induced by crowding agents, as a function of the number of monomers (N) and volume fraction (varphi c) of crowding particles. At varphic=0, the homopolymer undergoes transitions from a random coil to a helix, helical hairpin HH, and helix bundle HB structures depending on N, and temperature. Crowding induces chain compaction that can promote HH or HB formation depending on varphic. Typically, the helical content decreases which is reflected in the decrease in the transition temperatures that depend on varphic, N, and the size of the crowding particles.