Fig. 4.

Opening of a loop that is a part of the fractal globule (a), and the equilibrium globule (b). Globules of 32,000 monomers were folded by pairwise attractive interactions. The fractal globule was formed by Molecular Dynamics which keeps track of topological constrains, while the equilibrium globule was equilibrated folded by Monte Carlo simulations (Reith and Virnau 2010) that violate topological constrains leading to significant entanglement. On the next step of molecular dynamics simulation, attractive interactions for a region of 3,000 monomers were removed allowing the region to open up due to the chain entropy. In the fractal globule, the region opened up forming a large loop (a). The same region failed to open from the equilibrium globule (b) due chain entanglements in this state