methanofuran methanofuran methanofurans are a family of chemical compounds found in methanogenic archaea. these species feature a 2-aminomethylfuran linked to phenoxy group. at least three different end groups are recognized: r = tricarboxyheptanoyl (methanofuran), glutamyl-glutamyl (methanofuran b), tricarboxy-2-hydroxyheptanoyl (methanofuran c, see picture). structure of the methanofurans formylation of mfr methanofuran converts to formylmethanofuran in an early stage of methanogenesis. the enzyme formylmethanofuran dehydrogenase (ec: 1.2.99.5) formylates methanofuran using co2, the primary c1 source in methanogenesis. deformylation of mfr the enzyme formylmethanofuran:tetrahydromethanopterin formyltransferase catalyzes the transfer of the formyl group from formylmethanofuran to n5 on tetrahydromethanopterin, h4mpt. this enzyme has been crystallized; it contains no prosthetic group.