Enhanced Activity of the Cellulase Enzyme β-Glucosidase upon Addition of an Azobenzene-Based Surfactant

Abstract

β-Glucosidases catalyze the hydrolysis of cellobiose to glucose, which is often the rate-limiting step in the conversion of cellulose into fermentable sugars during bioethanol production. Thus, the structure and function of β-glucosidase from Aspergillus niger were examined in response to a photoresponsive azobenzene-based surfactant (4ethyl-4′(trimethylamino-butoxy)azobenzene bromide, azoTAB) as a means to enhance the enzyme activity. Light and neutron scattering data indicate that pure β-glucosidase exists as dimers or higher aggregates in solution that are progressively converted to monomers with an increasing azoTAB concentration. This transition is accompanied by a 60% increase in catalytic activity. In contrast, the enzyme is simply deactivated in the presence of conventional straight-chain hydrocarbon surfactants. Shape-reconstructed images obtained from SANS data demonstrate that azoTAB causes selective unfolding in the α/β sandwich domain that comprises the crystallographic dimer interface, consistent with the observed transition to monomers. Furthermore, this domain forms one side of a long cleft that begins at the active site and facilitates the nonproductive binding of substrate or longer oligosaccharides, which at times can block the active site. Indeed, kinetic data indicate that the azoTAB-induced increase in β-glucosidase activity is a result of diminished substrate inhibition, thus providing a unique means of obtaining glucose-tolerant β-glucosidases.

Tween® Preserves Enzyme Activity and Stability in PLGA Nanoparticles

“…Even in recent years this topic is being published in the literature with high interest and not completely understood as results show differences in the oligomer state being dependent on numerous factors such as the stabilizer, inhibitor, and also origins of the β-Glu. Studies looking at β-Glu derived from Aspergillus niger demonstrate that surfactants can change the equilibrium versus the monomer increasing its activity by 60% [78]. On the other hand, β-Glu from Spodoptera frugiperda and almond demonstrate higher activity in the homodimer form of the enzyme [79,80].…”

Advanced Strategies of Enzyme Activity Regulation for Biomedical Applications

“…Thus, an eight‐fold increase in enzyme activity was observed upon exposure to UV light. A similar approach can also regulate CA [45] and β‐glucosidase [46] activities on demand.…”

Beta-Glycosidase Activities of Lactobacillus spp. and Bifidobacterium spp. and The Effect of Different Physiological Conditions on Enzyme Activity

“…Endogluconases break off the inner β-1,4-glycosidic bonds of cellulose by hydrolysis to form new chain ends, and exoglucanases form soluble cellobiose units by cutting these new cellulose chains formed at the ends (Teugjas & Väljamäe, 2013;Pang et al, 2017). The enzyme β-glucosidase, which is responsible for the hydrolysis of cellulose, has been the focus of many studies because cellulose is the amplest substrate on earth and an essential renewable energy source in the future (Kara et al, 2011;Tamaki et al, 2016;Seidel & Lee, 2020). β-Glucosidases are a heterogeneous group of hydrolytic enzymes.…”