CRYSTAL-STRUCTURE OF NADH OXIDASE FROM THERMUS-THERMOPHILUS

The crystal structures of the flavin adenine dinucleotide (FAD) and fl avin mononucleotide (FMN) containing isoforms of NADH oxidase from The rmus thermophilus have been determined by isomorphous and molecular re placement and refined to 2.3 Angstrom and 1.6 Angstrom resolution with R-values of 18.5 % and 18.6 % respectively, The structure of the homo dimeric enzyme consists of a central 4-stranded antiparallel beta-shee t covered by helices, a more flexible domain formed by two helices, an d a C-terminal excursion connecting the subunits. The active sites are located in a deep cleft between the subunits, The binding site of the flavin cofactor lacks the common nucleotide binding fold and is diffe rent from the FMN binding site found in flavodoxins.