Hydrogen oxidation by Clostridium kluyveri.

In 1952, Korkes (1) reported that cell-free extracts of Clostri&urn kluyveri were capable of reducing pyridine nucleotides with hydrogen. Subsequent investigations have shown that a heatstable cofactor of undetermined nature present in boiled cell extracts was required (2). Pyridine nucleotide reduction with hydrogen has since been demonstrated in a number of other microorganisms (3-5). The present study was undertaken to explore in greater detail the alternative routes of hydrogen oxidation in C. kluyveri. Particular attention was paid to a comparison of the requirements for pyridine nucleotide, flavin nucleotide, and dye reduction, The available data suggest that the unknown cofactor does not function in the activation of hydrogen but acts between an activated hydrogen intermediate and pyridine nucleotide. Additional evidence is also presented showing that more than one enzyme is required for pyridine nucleotide reduction with hydrogen. A preliminary report of these results has been published (6).