Visible-light driven fumarate synthesis from pyruvate and gaseous CO2 with a hybrid system of photocatalytic NADH regeneration and dual biocatalysts

Abstract

Fumarate is a useful unsaturated dicarboxylate utilized as a precursor for unsaturated polyester resin and biodegradable plastics. Fumarate is partially produced from petroleum-derived materials; thus, it is necessary to establish a synthesis from renewable raw materials such as gaseous CO₂ and biobased compounds with an external renewable energy source such as solar light. In this work, the visible-light driven synthesis of fumarate from biobased pyruvate is reported, which uses CO₂ directly captured from the gas phase by a 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES)–NaOH buffer solution in combination with the NAD⁺ reduction system of triethanolamine (TEOA), water-soluble zinc porphyrin, zinc meso-tetra(4-sulfonatophenyl) porphyrin tetrasodium salt (ZnTPPS) and the Rh coordination complex ([Cp*Rh(bpy)(H₂O)]²⁺; Cp* = pentamethylcyclopentadienyl, bpy = 2,2′-bipyridyl). In addition, dual-biocatalysts consisting of malate dehydrogenase (oxaloacetate-decarboxylating; MDH; EC 1.1.1.38) from Sulfobus tokodaii and fumarase from porcine heart (FUM; EC 4.2.1.2) were used. It was found that pyruvate can be converted into L-malate with MDH by directly using CO₂ gas as a carboxylating agent in the presence of NADH. Moreover, the development of visible-light driven fumarate synthesis from gaseous CO₂ and pyruvate, employing a system with NADH regeneration and dual-biocatalysts as raw materials was also established.