Photochemical fixation of carbon dioxide: Enzymic photosynthesis of malic, aspartic, isocitric, and formic acids in artificial media

Daniel Mandler, Itamar Willner*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

107 Scopus citations

Abstract

Photosensitized regeneration of 1,4-dihydronicotinamide adenine dinucleotide phosphate (NADPH) with an artificial photosystem allows the enzymic fixation of CO2 through carboxylation of α-oxo acids using sacrificial electron donors. Pyruvic acid is carboxylated to malic acid and α-oxoglutaric acid is carboxylated to isocitric acid with the malic enzyme and isocitrate dehydrogenase (ICDH) as biocatalysts, φ = 1.9%. Malic acid formed through the photosensitized process is used as a synthetic building block for subsequent sesquestered enzymic transformations, and its conversion into aspartic acid is accomplished with fumarase and aspartase as biocatalysts. Photoreduction of CO2 to formate is accomplished in the presence of formate dehydrogenase (FDH) as catalyst. Photosensitized reduction of different bipyridinium relay systems, i.e. N,N′-dimethyl-4,4′-bipyridinium (MV2+) (1), N,N′-dimethyl-2,2′-bipyridinium (DM 2+) (2), N,N′-trimethylene-2,2′-bipyridinium (DT 2+) (3), and N,N′-tetramethylene-2,2′-bipyridinium (DQ2+) (4), to the corresponding radical cations yields reduced relays that act as cofactors for FDH, which mediates the reduction of CO 2 to formate. The quantum yield for formate formation is in the range φ = 0.5-1.6%.

Original languageAmerican English
Pages (from-to)997-1003
Number of pages7
JournalJournal of the Chemical Society, Perkin Transactions 2
Issue number6
DOIs
StatePublished - 1988

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