preprints.org > physical sciences > biophysics > doi: 10.20944/preprints202310.0074.v1

Preprint Article Version 1 Preserved in Portico This version is not peer-reviewed

Version 1 : Received: 1 October 2023 / Approved: 2 October 2023 / Online: 3 October 2023 (02:48:14 CEST)

Collagen is a triple-helical protein unique to the extracellular matrix, conferring rigidity and stability to tissues such as bone and tendon. For the [(PPG)10]3 collagen-mimetic peptide at room temperature, our molecular dynamics simulations show that these properties result in a remarkably ordered first hydration layer, of water molecules hydrogen-bonded to the backbone-carbonyl (bb-CO) oxygen atoms. This originates from the following observations. The radius of gyration attests that the PPG triplets are organized along a straight line, so that all triplets (excepting the ends) are equivalent. The solvent accessible surface area (SASA) for the bb-CO oxygens shows a repetitive regularity for every triplet. This leads to bb-CO⋯HOH occupancy following a similar regularity, similar also to the crystal-phase 0-2-1 water occupancy in the P-P-G triplet. The regularity is maintained in spite of the sub-nsec water exchange rate, because the bb-CO sites rarely remain vacant. The manifested ordered first-shell water molecules are expected to produce a cylindrical electrostatic potential around the peptide, that might guide cation diffusion in its vicinity.

collagen; water; hydration; radius of gyration; SASA; hydrogen-bond; residence time

Physical Sciences, Biophysics

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