Effect of sodium chloride on the structure and stability of spider silk's N-terminal protein domain

Greta Gronau, Zhao Qin, Markus J. Buehler

Research output: Contribution to journalArticle

20 Scopus citations

Abstract

A spider's ability to store silk protein solutions at high concentration is believed to be related to the protein's terminal domains. It has been suggested that a shift in salt concentration and pH can have a significant influence on the assembly process. Based on experimental data, a model has been proposed in which the N-terminal domain exists as a monomer during storage and assembles into a homodimer upon spinning. Here we perform a systematic computational study using atomistic, coarse-grained and well-tempered metadynamics simulation to understand how the NaCl concentration in the solution affects the N-terminal domain of the silk protein. Our results show that a high salt concentration, as found during storage, weakens key salt bridges between the monomers, inducing a loss in bond energy by 28.6% in a single salt bridge. As a result, dimer formation is less likely as 35.5% less energy is required to unfold the dimer by mechanical force. Conversely, homodimer formation appears to be more likely at low salt concentrations as the salt bridge stays at the lower energy state. The link between salt concentration, structure and stability of the N-terminal domain provides a possible molecular mechanism that prevents premature fiber formation during storage.

Original languageEnglish (US)
Pages (from-to)276-284
Number of pages9
JournalBiomaterials Science
Volume1
Issue number3
DOIs
StatePublished - Mar 1 2013
Externally publishedYes

ASJC Scopus subject areas

  • Biomedical Engineering
  • Materials Science(all)

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