title: Production of L-malic acid with fixation of HCO3(-) by malic enzyme-catalyzed reaction based on regeneration of coenzyme on electrode modified by layer-by-layer self-assembly method.
abstract: Malic enzyme prepared and purified from Brevundimonas diminuta IFO13182 catalyzed the decarboxylation reaction of malate to pyruvate and CO2 using NAD+ as the coenzyme, and the reverse reaction was used in the present study for L-malic acid production with fixation of HCO3(-) as a model compound for carbon source. The L-malic acid production was based on electrochemical regeneration of NADH on a carbon plate electrode modified by layer-by-layer adsorption of polymer-bound mediator (Alginic acid bound viologen derivative, Alg-V), polymer-bound coenzyme (Alginic acid bound NAD+, Alg-NAD+), and lipoamide dehydrogenase (LipDH). Electrochemical reduction of immobilized NAD+ catalyzed by LipDH in a multilayer film was achieved, and the L-malic acid production with HCO3(-) fixation system with layer-by-layer immobilization of Alg-V/LipDH/Alg-NAD+/malic enzyme multilayer film on the electrode gave an L-malic acid production of nearly 11.9 mmol and an HCO3(-) fixation rate of nearly 47.4% in a buffer containing only KHCO3 and pyruvic acid potassium salt, using a cation exchange membrane. The total turnover number of NADH within 48 h was about 19,000, which suggests that efficient NADH regeneration and fast electron transfer were achieved within the multilayer film, and that the modified electrode is a potential method for the fixation of HCO3(-) without addition of free coenzyme.
authors.affiliation: School of Material Science and Chemical Engineering, Tianjin Polytechnic University, Tianjin 300160, China.
authors.forename: Haitao
authors.initials: H
authors.lastname: Zheng
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ohno
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Nakamori
authors.forename: Shin-Ichiro
authors.initials: S
authors.lastname: Suye
mesh_terms: D000327:Adsorption; D000464:Alginates / Q000737:chemistry; D001639:Bicarbonates / Q000737:chemistry*; D002021:Buffers; D002245:Carbon Dioxide / Q000737:chemistry; D002384:Catalysis; D002412:Cations; D008058:Dihydrolipoamide Dehydrogenase / Q000737:chemistry; D004563:Electrochemistry / Q000379:methods; D004566:Electrodes; D020723:Glucuronic Acid / Q000737:chemistry; D006603:Hexuronic Acids / Q000737:chemistry; D008293:Malates / Q000737:chemistry*; D009243:NAD / Q000737:chemistry; D011108:Polymers / Q000737:chemistry; D012038:Regeneration; D013997:Time Factors
chemical_list: D000464:Alginates; D001639:Bicarbonates; D002021:Buffers; D002412:Cations; D006603:Hexuronic Acids; D008293:Malates; D011108:Polymers; D009243:NAD; D002245:Carbon Dioxide; C030298:malic acid; D020723:Glucuronic Acid; D008058:Dihydrolipoamide Dehydrogenase