Modulation of Transaminase Activity by Encapsulation in Temperature-Sensitive Poly(N-acryloyl glycinamide) Hydrogels

Smart hydrogels hold much potential for biocatalysis, not only for the immobilization of enzymes, but also for the control of enzyme activity. We investigated upper critical solution temperature-type poly N-acryloyl glycinamide (pNAGA) hydrogels as a smart matrix for the amine transaminase from Bacillus megaterium (BmTA). Physical entrapment of BmTA in pNAGA hydrogels results in high immobilization efficiency (>89 %) and high activity (97 %). The temperature-sensitiveness of pNAGA is preserved upon immobilization of BmTA and shows a gradual deswelling upon temperature reduction. While enzyme activity is mainly controlled by temperature, deactivation tended to be higher for immobilized BmTA (approximate to 62-68 %) than for free BmTA (approximate to 44 %), suggesting a deactivating effect due to deswelling of the pNAGA gel. Although the deactivation in response to hydrogel deswelling is not yet suitable for controlling enzyme activity sufficiently, it is nevertheless a good starting point for further optimization.

Automated summary

Smart hydrogels, specifically poly N-acryloyl glycinamide (pNAGA) hydrogels, have been explored as a potential matrix for immobilizing enzymes, with promising results in terms of immobilization efficiency and enzyme activity. The temperature-sensitive nature of pNAGA remains intact when used to immobilize the amine transaminase, resulting in a gradual deswelling effect as temperature decreases. Although enzyme activity is primarily temperature-controlled, immobilized BmTA shows higher deactivation rates compared to free BmTA, indicating a potential deactivating effect caused by the deswelling of the pNAGA gel.