Charge-modulated accessibility of tyrosine residues for silk-elastin copolymers cross-linking

• Published in: Biomacromolecules Vol. 23; no. 3; pp. 760 - 765
• Main Authors: Gonzalez-Obeso, Constancio, Backlund, Fredrik G., Kaplan, David L.
• Format: Journal Article
• Language: English
• Published: 03.02.2022
• ISSN: 1525-7797; 1526-4602
• DOI: 10.1021/acs.biomac.1c01192

The modulation of reaction kinetics with horseradish peroxidase (HRP)-catalyzed crosslinking of proteins remains a useful strategy to modulate hydrogel formation. Here, we demonstrate that the presence of positively charged lysines in silk elastin-like polymers (SELPs) impact the thermal transition temperature of these proteins, while the location in the primary sequence modulates the reactivity of the tyrosines. The positively charged lysine side chains decreased pi-pi interactions among the tyrosines and reduced the rate of formation and number of HRP-mediated dityrosine bonds, dependent on the proximity of the charged group to the tyrosine. The results suggest that the location of repulsive charges can be used to tailor the reaction kinetics for enzymatic crosslinking, providing further control of gelation rates for in situ gel formation, as well as the resulting protein-based gel characteristics.