Quantitative Model of the Phase Behavior of Recombinant pH-Responsive Elastin-Like Polypeptides

TitleQuantitative Model of the Phase Behavior of Recombinant pH-Responsive Elastin-Like Polypeptides
Publication TypeJournal Article
Year of Publication2010
AuthorsMacKay, JA, Callahan, DJ, FitzGerald, KN, Chilkoti, A
JournalBiomacromolecules
Volume11
Issue11
Pagination2873 - 2879
Date Published11/2010
ISSN1526-4602
Abstract

Quantitative models are required to engineer biomaterials with environmentally responsive properties. With this goal in mind, we developed a model that describes the pH-dependent phase behavior of a class of stimulus responsive elastin-like polypeptides (ELPs) that undergo reversible phase separation in response to their solution environment. Under isothermal conditions, charged ELPs can undergo phase separation when their charge is neutralized. Optimization of this behavior has been challenging because the pH at which they phase separate, pHt, depends on their composition, molecular weight, concentration, and temperature. To address this problem, we developed a quantitative model to describe the phase behavior of charged ELPs that uses the Henderson−Hasselbalch relationship to describe the effect of side-chain ionization on the phase-transition temperature of an ELP. The model was validated with pH-responsive ELPs that contained either acidic (Glu) or basic (His) residues. The phase separation of both ELPs fit this model across a range of pH. These results have important implications for applications of pH-responsive ELPs because they provide a quantitative model for the rational design of pH-responsive polypeptides whose transition can be triggered at a specified pH.

DOI10.1021/bm100571j
Short TitleBiomacromolecules
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