Optimization of Poly(<i>N</i>‑isopropylacrylamide)
as an Artificial Amidase
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Abstract
Poly(<i>N</i>-isopropylacrylamide)
microgel (NMG) has
been developed by adding various functional groups to control surface
charges, hydrophobicity, p<i>K</i><sub>a</sub> and protein
adsorption capacity. Here, we developed and optimized NMG anchored
with three types of functional groups as a polymeric catalyst to hydrolyze
amide bonds under optimized mild conditions. Various optimization
strategies were evaluated for efficient hydrolysis activity on a <i>p</i>-nitroaniline-based substrate by using a colorimetric assay.
Based on the results, we propose a mechanism to hydrolyze amide bonds
and determine the theoretical average distance, using NMG bearing
functional group of 1-vinylimidazole as the study model. The hydrolysis
of amide bonds was inhibited by a transition-state protease inhibitor,
which also confirmed the proposed reaction model for NMG. These results
provide an insight into the strategies developed to functionalize
hydrogels through an enzyme-mimic approach for future robust bio-
and chemical conversions as well as therapeutic utilities