Enzymes Suitable for Biorefinery to Coproduce Hexaric Acids and Electricity from Hexuronic Acids Derived from Biomass

Abstract

Hexarates are platform chemicals. Methods to produce d‐glucarate and d‐mannarate are desirable because these hexarates can be gained by oxidation of the corresponding hexuronates, which are abundantly found in algae and plants as the units of polyuronates. Oxidative production of the hexarates can be combined with a reductive reaction to coproduce electricity. An enzymatic biofuel cell is a device that enables this coproduction. To construct the cell, it is necessary to find enzymes that catalyze platform chemical production and are also suitable as anode catalysts. Here, we show the production of d‐glucarate and d‐mannarate from d‐glucuronate and d‐mannuronate, with both reactions catalyzed by pyrroloquinoline quinone (PQQ)‐dependent glucose dehydrogenase, in addition to the production of d‐glucarate from l‐guluronate by the PQQ domain of pyranose dehydrogenase from Coprinopsis cinerea. The enzymes are suitable as anode catalysts in biofuel cells that coproduce these hexarates and electricity.

Production of Hexaric Acids from Biomass

“…This simultaneous production mechanism is applicable to other chemicals. We confirmed the oxidation of d -glucuronate and d -mannuronate, both catalyzed by PQQ-GDH, and the oxidation of l -guluronate, catalyzed by the PQQ domain of pyranose dehydrogenase from Coprinopsis cinerea (DH PDH ) [138,139]. According to NMR measurements, the production of d -glucarate from the oxidation of d -glucuronate and l -guluronate and the production of d -mannarate from the d -mannuronate oxidation were confirmed.…”

“…This method reduces the energy required for producing chemicals and can even generate energy for other uses. The concept of a system that co-produces platform chemicals and electrical energy from biomass by demonstrating the simultaneous production of a hexaric acid and electrical energy using an enzymatic biofuel cell has been proposed [137,138,139]. The electrochemical oxidation of d -galacturonic acid and the production of meso -galactaric acid by a pyrroloquinoline quinone-dependent glucose dehydrogenase (PQQ-GDH)-modified electrode was confirmed [137,139].…”

Sustainable Galactarate‐Based Polymers: Multi‐Enzymatic Production of Pectin‐Derived Polyesters

“…A pyrroloquinoline quinone‐dependent glucose dehydrogenase (PQQ‐GDH) immobilized on an electrode was used for the production of GA . This biotechnological electrosynthesis is an appealing alternative because it does not require expensive cofactors or O 2 , and can be easily applied for the oxidation of other bioderived monomers, showing a great potential for the development of low‐cost and reagentless glucose‐based sensors and biofuel cells …”

Biocatalytic reductive amination as a route to isotopically labelled amino acids suitable for analysis of large proteins by NMR

“…Chemical strategies to prepare adeuterated amino acids oen rely on precious metals and expensive chiral ligands or auxillaries. [11][12][13][14][15][16] Such approaches can suffer from imperfect selectivity, diminished isotopic purities, and complex work-up procedures, which can make the product cost prohibitively high for structural biology research. As an alternative to chemo-routes, several biocatalytic strategies have also been demonstrated for preparing a-deuterated amino acids.…”