Mechanically inferior constituents in spider silk result in mechanically superior fibres by adaptation to harsh hydration conditions: A molecular dynamics study

Yoonjung Kim, Myeongsang Lee, Inchul Baek, Taeyoung Yoon, Sung Soo Na

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

Spider silk exhibits mechanical properties such as high strength and toughness that are superior to those of any man-made fibre (Bourzac 2015 Nature 519, S4-S6 (doi:10.1038/519S4a)). This high strength and toughness originates from a combination of the crystalline (exhibiting robust strength) and amorphous (exhibiting superb extensibility) regions present in the silk (Asakura et al. 2015 Macromolecules 48, 2345-2357 (doi:10.1021/acs.macromol.5b00160)). The crystalline regions comprise a mixture of poly-alanine and poly-glycine-alanine. Poly-alanine is expected to be stronger than poly-glycine-alanine, because alanine exhibits greater interactions between the strands than glycine (Tokareva et al. 2014 Acta Biomater. 10, 1612-1626 (doi:10.1016/j.actbio.2013.08.020)). We connect this characteristic sequence to the interactions observed upon the hydration of spider silk. Like most proteinaceous materials, spider silks become highly brittle upon dehydration, and thus water collection is crucial to maintaining its toughness (Gosline et al. 1986 Endeavour 10, 37-43 (doi:10.1016/0160-9327(86)90049-9)). We report on the molecular dynamic simulations of spider silk structures with different sequences for the crystalline region of the silk structures, of wild-type (WT), poly-alanine, and poly-glycine-alanine. We reveal that the characteristic sequence of spider silk results in the β-sheets being maintained as the degree of hydration changes and that the high water collection capabilities of WT spider silk sequence prevent the silk from becoming brittle and weak in dry conditions. The characteristic crystalline sequence of spider dragline silk is therefore relevant not for maximizing the interactions between the strands but for adaption to changing hydration conditions to maintain an optimal performance even in harsh conditions.

Original languageEnglish
Article number20180305
JournalJournal of the Royal Society Interface
Volume15
Issue number144
DOIs
Publication statusPublished - 2018 Jul 1

Fingerprint

Spiders
Silk
Molecular Dynamics Simulation
Hydration
Molecular dynamics
Alanine
Fibers
Glycine
Amino acids
Crystalline materials
Toughness
S 6
Water
Macromolecules
Dehydration
Mechanical properties

Keywords

  • hydration effects
  • material characterization
  • molecular dynamics
  • Spider silk

ASJC Scopus subject areas

  • Biotechnology
  • Biophysics
  • Bioengineering
  • Biomaterials
  • Biochemistry
  • Biomedical Engineering

Cite this

Mechanically inferior constituents in spider silk result in mechanically superior fibres by adaptation to harsh hydration conditions : A molecular dynamics study. / Kim, Yoonjung; Lee, Myeongsang; Baek, Inchul; Yoon, Taeyoung; Na, Sung Soo.

In: Journal of the Royal Society Interface, Vol. 15, No. 144, 20180305, 01.07.2018.

Research output: Contribution to journalArticle

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