Ameliorating enzyme functionality with temperature and pH responsive polymer interface

Abstract

Urease enzyme activity can be related to various issues, both in biological systems and in industrial processes. A significant breakthrough in addressing the challenge to maintain enzymatic activity involves the development of enzyme-polymer based bioconjugates. This entails the utilization of dual responsive polymer matrix involving pH-responsive polymer (2-acrylamido-2-methylpropane sulfonic acid (AMPS)), neutral polymer (N, N-dimethylacrylamide (DMA)), temperature-responsive polymer (N-isopropylacrylamide (NIPAM)), and urease derivative (UD) collectively known as [PAMPS-co-PDMA-co-PUD]-b-PNIPAM (ADUN) centered on the RAFT-Grafting through polymerization process. Kinetic assessments, including a comparative study between the free enzyme and urease linked in ADUN, were conducted using berthelot reagents at different pH and temperature levels. The Lineweaver–Burk plot was used to ascertain the Michaelis–Menten kinetic constant (Km) values, which unveiled strikingly similar Km values for the free enzyme and ADUN. This indicates that urease remains active for over a month when stored at room temperature and up to around 70 °C in the case of ADUN, while it becomes dormant in the case of free urease. The microenvironment of the bioconjugates remains intact for urease in acidic pH conditions and at temperatures ranging from mild to high, when the concentration exceeds the critical micelle concentration (CMC). In general, this approach highlights the prolonged durability and commercial adaptability of ADUN for wider uses.