Use of high activity enzyme preparations in neat organic solvents for organic synthesis

Abstract

The use of enzymes in nearly anhydrous organic solvents generally results in low initial rates/percentage conversions. The current review focuses on some biocatalyst designs like immobilization on nanomaterials, enzyme precipitated and rinsed with organic solvents (EPROS), crosslinked enzyme crystals (CLEC), crosslinked enzyme aggregates (CLEA), protein coated microcrystals (PCMC) and crosslinked protein coated microcrystals (CLPCMC) which show much better catalytic efficiency in such media as compared to other kinds of biocatalyst preparations. The basic methodology and principle behind these efficient designs are described. The relatively recent results on catalytic promiscuity as seen in low water media have also been covered. It is hoped that this will further encourage wider applications of enzymes in neat organic solvents in organic synthesis.

A combination of absorption and enzymatic biodegradation: phenol elimination from aqueous and organic phase

“…It was an expected result due to mass transfer limitations in the organic phase lowering the total activity of the enzyme [38,48,49]. Another explanation could be added which is based on solvent-substrate interactions which could lower the free energy of the substrate and thereby its reactivity.…”

“…It combines two unit processes, purification and immobilization, into a single operation. CLEAs have attracted increasing attention, due to their simplicity, broad applicability, long conservation and high stability in organic solvents [36][37][38][39]. The last characteristic is the main issue which could be exploited in the design of an integrated process (Absorption/enzymatic biocatalysis) for phenol degradation as a proof of feasibility towards VOCs treatment.…”

Catalytic activity and structural stability of three different Bacillus enzymes in water/organic co-solvent mixtures

“…However, exploring advantages with aqueous-organic systems or even neat organic solvents are limited by the risk of enzyme inactivation and the environmentally hazardous nature of solvents. Despite this, significant progress has been made towards the development of environment-friendly strategies for stabilizing enzymes in organic co-solvents [9,12].…”

Improved Enantioselectivity of Subtilisin Carlsberg towards Secondary Alcohols by Protein Engineering

“…[28,29] Various methods (e.g.,a dditives, cross-linked enzyme aggregates (CLEA), surfactants, and immobilization) have been explored to improvei ts activity in organic solventa nd at elevated temperatures. [13,16,[30][31][32][33][34][35] Previously,p retreatmento fS Cw ith KCl salt or surfactants (Brij56a nd octyl-b-d-glycopyranoside) prior to lyophilization improvedt he enzyme performance in terms of activity,o perational stability, and enantioselectivity in organic solvent. [13,36] It was previously proposed that the enzyme-treatment method appliedprior to immobilization was more important for enzyme activity and enantioselectivity than the type of immobilizationt echnique.…”

“…However, the main bottleneck for efficient application of such stabilized SC preparations is low stability in organic solvent . Various methods (e.g., additives, cross‐linked enzyme aggregates (CLEA), surfactants, and immobilization) have been explored to improve its activity in organic solvent and at elevated temperatures . Previously, pretreatment of SC with KCl salt or surfactants (Brij 56 and octyl‐β‐ d ‐glycopyranoside) prior to lyophilization improved the enzyme performance in terms of activity, operational stability, and enantioselectivity in organic solvent .…”