Dual-Enzyme Metal Hybrid Crystal for Direct Transformation of Whey Lactose into a High-Value Rare Sugar D-Tagatose: Synthesis, Characterization, and a Sustainable Process

Abstract

A dual-enzyme metal–organic hybrid crystal was constructed through self-assembling of manganese phosphate embedded with β-galactosidase and L-arabinose isomerase for facile synthesis of rare sugar D-tagatose. The synthesized crystal-like hierarchical system (MnHC@β-Gal+L-AI) was extensively characterized for structural features and catalytic reactions. The results indicated that upon immobilization onto the hybrid crystal, the activity of β-galactosidase and L-arabinose iomerase was enhanced by a factor of 1.6- and 1.5-fold, respectively. The developed MnHC@β-Gal+L-AI exhibited excellent efficiency with a net equilibrium level conversion of low-cost substrate whey lactose (100%) into D-glucose (∼50%), D-galactose (∼25%), and D-tagatose (∼25%). In addition, the fabricated hybrid crystals displayed cofactor regeneration ability. Therefore, the developed hybrid system was observed to be efficiently reused more than 5 times in a batch level conversion. Hence, the developed dual-enzyme-based hybrid crystal provides a platform for direct transformation of whey lactose into rare sugar D-tagatose.

Rational Design to Enhance Enzyme Activity for the Establishment of an Enzyme–Inorganic Hybrid Nanoflower Co-Immobilization System for Efficient Nucleotide Production

“…Many immobilization techniques have been developed for the production of high-value-added products. , Among various methods, enzyme–inorganic hybrid nanoflowers with a high specific surface area and good biocompatibility have attracted widespread attention . In addition to the advantages of simple preparation and operation, easy separation, and low cost, nanoflowers also support the co-immobilization of multiple enzymes and have a wide range of uses. − …”

Biocatalytic Foams from Microdroplet‐Formulated Self‐Assembling Enzymes

“…To further demonstrate that the novel foam materials can be used for biocatalytic production processes, we chose to produce a challenging product, the rare sugar tagatose. [37] Commonly L-arabinose isomerase is being used as either free or immobilized enzyme, or in whole-cell catalysis, to produce D-tagatose by isomerization from D-galactose, leading to productivities for free or immobilized isomerase of 0.3 -9.6 g L −1 h −1 [38][39][40][41][42] and of 0.21 -1.13 g L −1 h −1 for synthesis by whole-cells. [37,43,44] Recently, oxidoreductive reactions have been used to overcome the thermodynamic equilibrium of the isomerization reaction and to improve the purification of the final product.…”

Nondairy food applications of whey and milk permeates: Direct and indirect uses

“…(2020) created a metal–organic hybrid crystal from manganese phosphate embedded with β‐galactosidase and l ‐arabinose isomerase for direct conversion of lactose into d ‐tagatose in whey. Results showed that the crystals exhibited an overall greater enzymatic activity/efficacy compared to the use of free enzymes, and complete hydrolysis of lactose into a mixture of glucose (∼50%), d ‐galactose (∼25%), and d ‐tagatose (∼25%) in sweet whey could be achieved in 24 h (Rai et al., 2020). The crystals also showed good reusability and can be easily removed after the transformation reaction using centrifugation.…”