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CRYSTAL STRUCTURE OF THERMITASE AND STABILITY OF SUBTILISINS
A.V. TEPLYAKOV, I. P. KURANOVA, E. G. HARUTYUNYAN, C. FRÖMMEL *, W. E. HÖHNE *
Institute of Crystallography, Academy of Sciences of the USSR, Moscow; *Institute for Biochemistry, Humboldt University, Berlin
Abstract: Crystal structure of thermitase, a serine proteinase from Thermoactinomyces vulgaris , has been determined by X-ray diffraction at 1,4 Å resolution. The atomic model of thermitase refined to an fl-factor of 0,149 contains 1997 protein atoms, 182 water molecules and 2 Ca2+ ions. The tertiary structure of thermitase is similar to that of subtilisin BPN'. The greatest varyations are connected with insertions and deletions in the amino acid sequence, which are located on the surface of the molecule. Higher thormostability of thermitase can be explained in terms of the three-dimensional structure. The Ca2+ ions, bound to the protein molecule, as well as the ionic and hydrophobic interactions are supposed to give the main contribution to the stabilization of the structure.
Russian Journal of Bioorganic Chemistry 1990, 16 (4):437-447