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Critical role of the motor density and distribution on polar active polymers

Surabhi Jaiswal*, Prithwiraj Maity, and Snigdha Thakur†

Marisol Ripoll‡

  • *Contact author: surabhi19@iiserb.ac.in
  • †Contact author: sthakur@iiserb.ac.in
  • ‡Contact author: m.ripoll@fz-juelich.de
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Phys. Rev. Research 8, 013096 – Published 28 January, 2026

DOI: https://doi.org/10.1103/j1lq-6phk

Abstract

Polar polymer activity underlies numerous cellular processes driven by molecular motors or enzymes. Active polymers with activity on all constituent monomers display compact globular structure, while polymers with only head activity are known to result in stretched configurations. However, most biological and synthetic polymers feature activity localized in just a few sites, a scenario that significantly differs from both previous limits. In this work, we investigate how the density and distribution of motors critically influence the conformational and dynamical properties of polar active polymers. Using overdamped Langevin dynamics simulations, we show that globular conformations for high motor densities change to stretched ones for the more realistic moderate or low density of motors. Interestingly, the polymer's velocity exhibits a nonmonotonic dependence on motor density, with maximum propulsion at intermediate densities. Furthermore, the location of the first motor profoundly impacts polymer conformations; even a slight shift leads to drastic differences between coiled and stretched states. Our findings reveal that motor placement and density govern the structural transitions, characteristic timescales, and propulsion dynamics of polar active polymers, which will have numerous practical implications in the design and understanding of active synthetic and biopolymers.

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Phys. Rev. Research 8, 013096– Published 28 January, 2026
  • Received 15 March 2025
  • Accepted 16 December 2025
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