pH-Dependent Dimerization and Salt-Dependent Stabilization of the N-terminal Domain of Spider Dragline Silk—Implications for Fiber Formation


  • This work was supported by CIPSM and the Deutsche Forschungsgemeinschaft (to H.K.), the Elitenetzwerk Bayern, CompInt (to F.H.), and BMBF grant 13N9736 (to T.S.). We want to thank Lukas Eisoldt for providing plasmids of N1 and N2, and Dr. Martin Humenik for support with the SEC-MALS experiments.


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One of the toughest protein fibers: The N-terminal domain (NTD) of spider dragline silk shows a pH-dependent monomer–dimer equilibrium: The N-terminal domain silk protein is stored as a stabilized monomer at neutral pH and high salt concentration, whereas during fiber assembly at a lower pH value this domain is able to form antiparallel dimers. Multivalent linking results in endless and highly stable fibers (see picture).