Welcome to the new version of CaltechAUTHORS. Login is currently restricted to library staff. If you notice any issues, please email coda@library.caltech.edu
Published March 15, 2017 | Supplemental Material + Accepted Version
Journal Article Open

Analysis and control of chain mobility in protein hydrogels


Coiled-coil domains can direct the assembly of protein block copolymers into physically crosslinked, viscoelastic hydrogels. Here we describe the use of fluorescence recovery after photobleaching (FRAP) to probe chain mobility in reversible hydrogels assembled from engineered proteins bearing terminal coiled-coil domains. We show that chain mobility can be related to the underlying dynamics of the coiled-coil domains by application of a 3-state "hopping" model of chain migration. We further show that genetic programming allows the effective mobility of network chains to be varied 500-fold through modest changes in protein sequence. Destabilization of the coiled-coil domains by site-directed mutagenesis increases the effective diffusivity of probe chains. Conversely, probe mobility is reduced by expanding the hydrophobic surface area of the coiled-coil domains through introduction of the bulky leucine surrogate homoisoleucine. Predictions from the 3-state model imply asymmetric sequential binding of the terminal domains. Brownian Dynamics simulations suggest that binding asymmetry is a general feature of reversible gels, arising from a loss in entropy as chains transition to a conformationally restricted bridged state.

Additional Information

© 2017 American Chemical Society. Received: December 30, 2016; Published: February 22, 2017. We thank Steven Olsen and the Division of Chemistry and Chemical Engineering Instrument Shop for machining sample holders for the FRAP experiments. We also thank David Koos, Andres Collazo and the Biological Imaging Facility of the Caltech Beckman Institute for training and assistance in operating the confocal microscope. We thank John Bagert, Lawrence Dooling, and Cole DeForest for helpful discussions during the preparation of the manuscript. This work was supported by grant number DMR-1506483 from the Biomaterials Program of the U. S. National Science Foundation. A.K.O. acknowledges support by the National Science Foundation Graduate Research Fellowship under Grant No. DGE-1144469 and an HHMI Gilliam Fellowship. The authors declare no competing financial interest.

Attached Files

Accepted Version - jacs_2E6b13146.pdf

Supplemental Material - ja6b13146_si_001.pdf


Files (4.6 MB)
Name Size Download all
1.8 MB Preview Download
2.9 MB Preview Download

Additional details

August 19, 2023
October 24, 2023