Three-dimensional structure of the enzyme dimanganese catalase from Thermus thermophilus at 1 angstrom resolution

The crystal structures of two forms of the enzyme dimanganese catalase from Thermus Thermophilus (native and inhibited by chloride) were studied by X- ray diffraction analysis at 1.05 and 0.98 Angstrom resolution, respectively . The atomic models of the molecules were refined to the R factors 9.8 and 10%, respectively. The three-dimensional molecular structures are character ized in detail. The analysis of electron-density distributions in the activ e centers of the native and inhibited enzyme forms revealed that the most f lexible side chains of the amino acid residues Lys162 and Glu36 exist in tw o interrelated conformations. This allowed us to obtain the structural data necessary for understanding the mechanism of enzymatic activity of the dim anganese catalase. (C) 2000 MAIK "Nauka/Interperiodica".