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Dynamic Properties of Artificial Protein Hydrogels Assembled through Aggregation of Leucine Zipper Peptide Domains

Shen, Wei and Kornfield, Julia A. and Tirrell, David A. (2007) Dynamic Properties of Artificial Protein Hydrogels Assembled through Aggregation of Leucine Zipper Peptide Domains. Macromolecules, 40 (3). pp. 689-692. ISSN 0024-9297. https://resolver.caltech.edu/CaltechAUTHORS:20150114-134355362

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Abstract

Network relaxation dynamics of hydrogels formed from a genetically engineered multidomain protein (AC_(10)A, where A is an associative leucine zipper domain and C_(10) is a random-coil polyelectrolyte domain) were investigated by shear rheometry. Physical gels form by tetrameric association of the leucine zipper end-blocks (A). The longest stress relaxation time (τ_r) of these gels varies strongly with pH, increasing from τ_r ≈ 80 s at pH 8.0 to τ_r ≈ 1000 s at pH 7.0. The rate of strand exchange of the end-blocks was studied by using fluorescence quenching of the labeled form of the A domain. Fluorescence is quenched in solutions of fluorescein-labeled A; dequenching occurs when labeled A is mixed with a 60-fold excess of the unlabeled peptide. The dequenching transient after mixing reveals the characteristic strand exchange time (τ_e) of the A domain. As pH decreases from 8.0 to 7.0, τ_e increases from ca. 200 s to ca. 4500 s. Thus, τ_r of AC_(10)A hydrogels and τ_e of the A domain vary in parallel with pH. The strong correlation between macroscopic and molecular properties indicates that network relaxation is regulated by the lifetime of associations in the transient network. Because the rate of leucine zipper strand exchange is sensitive to interstrand electrostatic interactions, the relaxation behavior of artificial protein hydrogels can be engineered systematically by genetic programming of the amino acid sequence.


Item Type:Article
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http://dx.doi.org/10.1021/ma0615194DOIArticle
http://pubs.acs.org/doi/abs/10.1021/ma0615194PublisherArticle
http://pubs.acs.org/doi/suppl/10.1021/ma0615194/suppl_file/ma0615194si20061121_061257.pdfPublisherSupporting Information
ORCID:
AuthorORCID
Kornfield, Julia A.0000-0001-6746-8634
Tirrell, David A.0000-0003-3175-4596
Additional Information:© 2007 American Chemical Society Received July 6, 2006; Revised Manuscript Received November 21, 2006 The authors acknowledge the NSF Center for the Science and Engineering of Materials for financial support.
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Issue or Number:3
Record Number:CaltechAUTHORS:20150114-134355362
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20150114-134355362
Official Citation:Dynamic Properties of Artificial Protein Hydrogels Assembled through Aggregation of Leucine Zipper Peptide Domains Wei Shen, Julia A. Kornfield and David A. Tirrell Macromolecules 2007 40 (3), 689-692
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:53243
Collection:CaltechAUTHORS
Deposited By: Anne Hormann
Deposited On:16 Jan 2015 04:41
Last Modified:03 Oct 2019 07:48

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