EC Number |
---|
1.7.2.2 | - |
1.7.2.2 | alone or in complex with nitrite and cyanide, hanging drop vapor diffusion method, using 0.2 M trisodium citrate dihydrate, 0.1 M Tris-HCl pH 8.5 and 30% (v/v) PEG 400 |
1.7.2.2 | apoenzyme and its complexes with the substrate nitrite and the inhibitor azide. The subunit of NiR consists of the N-terminal domain which has an unique fold and contains three hemes and the catalytic C-terminal domain which hosts the remaining five hemes. The complete set of eight hemes forms a spatial pattern characteristic of other multiheme proteins, including structurally characterized octaheme cytochromes. The catalytic machinery comprises the lysine residue at the proximal position of the catalytic heme, the catalytic triad of tyrosine, histidine, and arginine at the distal side, channels for the substrate and product transport with a characteristic gradient of electrostatic potential, and, two conserved Ca2+-binding sites. In addition, the enzyme has a covalent bond between the catalytic tyrosine and the adjacent cysteine and an unusual topography of the product channels that open into the void interior space of the protein hexamer |
1.7.2.2 | ccNIR as apoenzyme or with bound sulfite or nitrite to the catalytic heme center, X-ray diffraction structure determination and analysis at 1.30-1.75 A resolution |
1.7.2.2 | crystallization of cytochrome c552, 2.2 A resolution |
1.7.2.2 | crystals are grown by the vapour-diffusion technique by mixing equal amounts of protein and reservoir solution, which contains about 10% (w/v) PEG 4K in 0.1 M HEPES pH 7.5 buffer |
1.7.2.2 | diffraction data sets with increasing absorbed doses. The structures reveal gradual changes associated with the reduction of the catalytic hemes by X-rays. The conversion of the nitrite ions bound in the active sites to NO species is observed, which is the beginning of the catalytic reaction. For the free form, an increase in the distance between the oxygen ligand bound to the catalytic heme and the iron ion of the heme takes place. In the sulfite complex no enzymatic reaction is detected |
1.7.2.2 | enzyme in complex with nitrite |
1.7.2.2 | hanging drop vapour diffusion method |
1.7.2.2 | hanging drop vapour diffusion method, structure determined to 2.3 A resolution |