Effects of topological constraints on globular polymers

Area of Science:

• Polymer Physics
• Computational Biophysics
• Materials Science

Background:

• Topological constraints influence polymer equilibrium and dynamics.
• Chromosome organization is affected by topological constraints.
• Systematic studies on topological effects in compact polymers are lacking.

Purpose of the Study:

• To systematically investigate the effects of topological constraints on the equilibrium state of single compact polymers.
• To compare the properties of knotted and unknotted polymers using simulations.

Main Methods:

• Utilized computational simulations to model polymer systems.
• Analyzed spatial and topological states of polymer subchains.
• Calculated fractal dimension of polymer surfaces.

Main Results:

• Unknotted polymers form compact globules with subchains that are mostly unknotted.
• These globules exhibit asymptotically compact random-chain (RG) scaling (RG(s)∼s1/3).
• The surface fractal dimension (db=2.8) indicates excessive interpenetration and contacts, differing from idealized crumpled globule models.

Conclusions:

• Topologically constrained equilibrium states of polymers differ significantly between knotted and unknotted chains.
• Simulated unknotted polymer globules resemble, but do not perfectly match, conjectured crumpled globule models.
• The findings highlight the importance of topology in polymer self-assembly and organization.