CARBOXYLATION REACTIONS OF PYRUVATE-FERREDOXIN OXIDOREDUCTASE AND 2-OXOGLUTARATE - FERREDOXIN OXIDOREDUCTASE FROM HYDROGENOBACTER-THERMOPHILUS-TK-6

Enzymatic reactions involving pyruvate:ferredoxin oxidoreductase and 2 -oxoglutarate: ferredoxin oxidoreductase from a thermophilic, aerobic, chemolithoautotrophic, and hydrogen-oxidizing bacterium, Hydrogenobac ter thermophilus TK-6, were investigated as the CO2 exchange reaction and CO2 fixation reaction using ferredoxin isolated from the same orga nism as a reductant. The reduced ferredoxin was required in the pyruva te synthetic reaction and the 2-oxoglutarate synthetic reaction by a c ell extract that had been treated with a PD-10 column to remove the lo w molecular weight substances, [C-14]Pyruvate and [C-14]2-oxoglutarate were detected as products of pyruvate synthetic and 2-oxoglutarate sy nthetic reactions, respectively, Further evidence for the operation of pyruvate:ferredoxin oxidoreductase and 2-oxoglutarate: ferredoxin oxi doreductase was obtained from experiments on CO2 exchange reactions us ing the purified enzymes.