Interfacial Anchoring of Haloalkane Dehalogenase LinB for Efficient 1-Bromobutane Degradation

Abstract

The enzymatic degradation of volatile haloalkane waste gases, which are commonly generated from halogenation reactions in organic chemical synthesis, is challenging due to their low concentration and poor aqueous solubility. In this study, we proposed a novel process that integrated in situ substrate absorption using an organic solvent with enzymatic degradation, using haloalkane dehalogenase LinB as a model enzyme, 1-bromobutane as a volatile haloalkane, and n-dodecane as the absorbent. An amphiphilic polymer, Pluronic F127, was grafted onto LinB, resulting in the Pluronic-LinB conjugate being anchored at the n-dodecane/water interface, as evidenced by confocal laser scanning microscopy. The interfacial anchoring facilitated the uptake of 1-bromobutane by LinB, thereby enhancing catalytic hydrolysis. Pluronic-LinB exhibited a significantly enhanced flexibility at the n-dodecane/water interface, as shown by low-field nuclear magnetic resonance. All these increased enzymatic performances, as could be interpreted from the kinetic parameters. Moreover, molecular dynamic simulations revealed that the attached polymer enhanced the conformational dynamics of helix and loop motifs forming the substrate channels of the enzyme, increased the water flux, and reduced the residence time of water molecules in the active pocket. This work has presented a novel molecular engineering strategy to expand the application spectrum of enzymatic catalysis.