Chitin and chitosan binding to the α-chitin crystal; a molecular dynamics study

Hudek, Magdalena and Kubiak-Ossowska, Karina and Johnston, Karen and Ferro, Valerie A. and Mulheran, Paul A. (2023) Chitin and chitosan binding to the α-chitin crystal; a molecular dynamics study. ACS Omega. ISSN 2470-1343 (https://doi.org/10.1021/acsomega.2c07495)

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Abstract

Understanding the binding of chitosan oligomers to the surface of a chitin nanocrystal is important for improving the enzymatic de-acetylation of chitin and for the design of chitin/chitosan composite films. Here, we study the binding of several chito-oligomers to the (100) surface of an α-chitin crystal using molecular dynamics (MD), steered MD and umbrella sampling. The convergence of the free energy was carefully considered and yielded a binding energy of -12.5 kcal mol−1 and -2 kcal mol−1 for 6-monomer-long chitin and uncharged chitosan oligomers respectively. We also found that the results for the umbrella sampling were consistent with the force profile from the steered MD and with classical MD simulations of the adsorption process. Our results give insight into the molecular-scale interactions, which can be helpful for the design of new chitin composite films. Furthermore, the free energy curves we present can be used to validate coarse-grained models for chitin and chitosan, which are necessary to study the self-assembly of chitin crystals due to the long timescale of the process.

ORCID iDs

Hudek, Magdalena, Kubiak-Ossowska, Karina, Johnston, Karen ORCID logoORCID: https://orcid.org/0000-0002-5817-3479, Ferro, Valerie A. ORCID logoORCID: https://orcid.org/0000-0003-1967-3603 and Mulheran, Paul A. ORCID logoORCID: https://orcid.org/0000-0002-9469-8010;