Formylmethanofuran Synthesis by Formylmethanofuran Dehydrogenase from Methanobacterium thermoautotrophicum Marburg

Formylmethanofuran dehydrogenase was purified 30-fold from the cytosolic fraction of cell extract of Methanobacterium thermoautotrophicum (Marburg) and shown for the first time to synthesize in vitro formylmethanofuran from methanofuran and carbon dioxide with electrons donated by titanium(III) citrate. The reaction was methanofuran-, CO 2-, and Ti 3+-dependent. Active enzyme could be purified from cells grown with either molybdenum or tungsten as the sole group VIA trace element. The active form of formylmethanofuran dehydrogenase had an apparent molecular mass of 530 kDa as determined by gel filtration chromatography and was found to copurify with a hydrogenase.