Visible light-induced formic acid synthesis from HCO3- with formate dehydrogenase and water-soluble zinc porphyrin

Photochemical and enzymatic synthesis of formic acid was investigated from HCO3- with formate dehydrogenase (FDH) from Saccharomyces cerevisiae and reduced methylviologen (MV2+) produced by the visible light photosensitization of zinc tetrakis(4-methylpyridyl) porphyrin (ZnTMPyP) in the presence of triethanolamine (TEOA) as an electron donating reagent. Irradiation of a solution containing TEOA, ZnTMPyP, MV2+, NaHCO3 and FDH in potassium phosphate buffer, with visible light resulted in formic acid production and HCO3- consumption. The optimum FDH activity was 20 units and the amount of formic acid and the yield of HCO3- to formic acid after 4 h irradiation were estimated to be 50 mumol.dm(-1) and 5.0%, respectively.