Microwave-assisted synthesis of butyl galactopyranoside catalyzed by β-galactosidase from Thermotoga naphthophila RKU-10

Current Strategies for Real-Time Enzyme Activation

Enzyme activation is a powerful means of achieving biotransformation function, aiming to intensify the reaction processes with a higher yield of product in a short time, and can be exploited for diverse applications. However, conventional activation strategies such as genetic engineering and chemical modification are generally irreversible for enzyme activity, and they also have many limitations, including complex processes and unpredictable results. Recently, near-infrared (NIR), alternating magnetic field (AMF), microwave and ultrasound irradiation, as real-time and precise activation strategies for enzyme analysis, can address many limitations due to their deep penetrability, sustainability, low invasiveness, and sustainability and have been applied in many fields, such as biomedical and industrial applications and chemical synthesis. These spatiotemporal and controllable activation strategies can transfer light, electromagnetic, or ultrasound energy to enzymes, leading to favorable conformational changes and improving the thermal stability, stereoselectivity, and kinetics of enzymes. Furthermore, the different mechanisms of activation strategies have determined the type of applicable enzymes and manipulated protocol designs that either immobilize enzymes on nanomaterials responsive to light or magnetic fields or directly influence enzymatic properties. To employ these effects to finely and efficiently activate enzyme activity, the physicochemical features of nanomaterials and parameters, including the frequency and intensity of activation methods, must be optimized. Therefore, this review offers a comprehensive overview related to emerging technologies for achieving real-time enzyme activation and summarizes their characteristics and advanced applications.

Screening novel β-galactosidases from a sequence-based metagenome and characterization of an alkaline β-galactosidase for the enzymatic synthesis of galactooligosaccharides

βgalactosidases have wide industrial applications in lactose hydrolysis and transglycosylation reactions. Therefore, there is a need to mine novel and high-quality β-galactosidases with good tolerance and novel features from harsh environments and genomic databases. In this study, an Escherichia coli β-galactosidase-deficient host, ΔlacZ(DE3)pRARE, was constructed by the CRISPR-Cas9 system for screening active β-galactosidases. Of thirty selected β-galactosidases, twelve novel enzymes showed β-galactosidase activity, four of which were purified for further study. BGal_375 exhibited maximal activity at pH 8 and 50 °C. The concentrations of two types of galactooligosaccharides, tri- and tetra-saccharides, produced by BGal_375, reached 64.53 g/l and 8.32 g/l, respectively. BGal_375 displayed a K_m value of 1.65 mM and k_cat value of 53 s^-1 for p-nitrophenyl-β-d-galactopyranoside (pNPG). BGal_137, BGal_144-3, and BGal_145-2 showed promising hydrolytic activity for pNPG. BGal_137 is a homodimer while BGal_144-3, BGal_145-2, and BGal_375 were all monomeric. This study provided an efficient solution for the identification of new β-galactosidases from metagenomic data, and an alkaline β-galactosidase efficient for the synthesis of galactooligosaccharides was obtained, which is important for potential industrial applications.