UVB light influence on the laccase enzyme catalytic activity in reverse micelles and in homogeneous aqueous medium

Abstract

Laccase is a versatile enzyme for the oxidation of environmental contaminants and display great potential in many applications; however, it undergoes photo-degradation when irradiated with UVB light.The instability of this biomolecule can be improved by immobilization in different encapsulation media. In the present contribution, reverse micelles of AOT were used with this purpose. Moreover, the use of these kind of media can be relevant in the sense that they be able to mimetic the complexity of contaminated aquatic microenvironments where the enzymes can be used as biological remediation agents.The laccase activity from spectroscopic data, using syringaldazine as substrate has been studied in the absence and in the presence of reverse micelles of 0.15 M AOT/isooctane at W 0 ([H 2 O]/[AOT]) =30, before and after irradiation of the enzyme with UVB light.The kinetic parameters, i.e. Michaelis-Menten constant (K M ), catalytic constant (k CAT ) and catalytic e ciency (k CAT / K M ) were determinate in the micellar system and in aqueous medium and comparatively analyzed. From this comparison, it was found that the enzyme presents a considerably photo-protection when irradiated with UVB light in reverse micelles as compared with the aqueous medium. Moreover, taking into account the distribution of the substrate in the two pseudo-phases (micellar and organic solvent), the activity of the enzyme is signi cantly preserved in the micellar medium.

Unravelling the Mechanism of Elastin-like Polypeptide-Enzyme Fusion Stabilization in Organic Solvents

“…Multiple strategies have been employed to overcome these challenges and improve both substrate scope and catalytic performance − ; however, the major bottlenecks remaining for broadened industrial translation are the burden of labor-intensive screening steps, low economic viability, and detailed knowledge of the enzyme mechanism required to guide manipulations of the gene of interest. − Commonly used strategies to address enzyme stability and downstream processing challenges rely on compartmentalization via immobilization onto an external support material via entrapment, adsorption, or covalent cross-linking. ,, A variety of support materials have been used, including synthetic polymers, − protein cages, , carbohydrate-based biopolymers, , and vesicles. , Unfortunately, these supports often restrict enzyme and substrate mobility, leading to diffusion limitations that can negatively impact reaction rates and increase denaturization rates. , When the reaction medium contains high organic solvent content, the most commonly employed method for stabilizing the enzymes in hostile environments such as this is their dispersion within micelle or reverse micellar structures . The most widely used surfactants to stabilize enzymes within micelle or reversed micellar structures of high organic composition are sodium bis­(2-ethylhexyl) sulfosuccinate, Brij 30, or cetyltrimethylammonium bromide. − …”