Design of combined crosslinked enzyme aggregates (combi-CLEAs) of ß-galactosidase and glucose isomerase for the one-pot production of fructose syrup from lactose.

A new bi-enzymatic catalyst has been produced by precipitation and crosslinking (combi-CLEAs) of ß-galactosidase and glucose isomerase for catalyzing the cascade reactions of lactose conversion into fructose, producing a lactose-fructose syrup (LFS). Glucose isomerase was chemically aminated to increase its reactive surface groups for favour the crosslinking step. The effect of ß-galactosidase to glucose isomerase activity ratio and glutaraldehyde to protein mass ratio in combi-CLEAs production was evaluated. The selected combi-catalyst was successfully used in the production of fructose syrup from lactose in a single reaction vessel. The biocatalyst could be used at least in five sequential batches of LFS production, remaining fully stable after a total of 50 h of reaction, obtaining a product of constant quality. A robust bi-enzymatic catalyst was produced that can be repeatedly used in LFS production, an attractive mild sweetener for the dairy food industry.

Recent Advances in Catalyzed Sequential Reactions and the Potential Use of Tetrapyrrolic Macrocycles as Catalysts.

Complexes of porphyrins and of other similar tetrapyrrolic macrocycles are extensively explored as catalysts for different chemical processes, and the development of solid catalysts for heterogeneous processes using molecules with the ability to act as multifunctional catalysts in one-pot reactions is increasing and can lead to the wider use of this class of molecules as catalysts. This mini review focuses on the application of this class of complexes as catalysts in a variety of sequential one-pot reactions.

Carbon dioxide/methanol conversion cycle based on cascade enzymatic reactions supported on superparamagnetic nanoparticles

ABSTRACT The conversion of carbon dioxide into important industrial feedstock is a subject of growing interest in modern society. A possible way to achieve this goal is by carrying out the CO2/methanol cascade reaction, allowing the recycle of CO2 using either chemical catalysts or enzymes. Efficient and selective reactions can be performed by enzymes; however, due to their low stability, immobilization protocols are required to improve their performance. The cascade reaction to reduce carbon dioxide into methanol has been explored by the authors, using, sequentially, alcohol dehydrogenase (ADH), formaldehyde dehydrogenase (FalDH), and formate dehydrogenase (FDH), powered by NAD+/NADH and glutamate dehydrogenase (GDH) as the co-enzyme regenerating system. All the enzymes have been immobilized on functionalized magnetite nanoparticles, and their reactions investigated separately in order to establish the best performance conditions. Although the stepwise scheme led to only 2.3% yield of methanol per NADH; in a batch system under CO2 pressure, the combination of the four immobilized enzymes increased the methanol yield by 64 fold. The studies indicated a successful regeneration of NADH in situ, envisaging a real possibility of using immobilized enzymes to perform the cascade CO2-methanol reaction.