STRUCTURES OF DIMORPHS OF RUBUREDOXIN FROM DESULFOVIBRIO VULGARIS MIYAZAKI F. S. Misaki, K. Muneo, S. Sugiyama, Y. Higuchi and N. Yasuoka, Faculty of Science, Himeji Institute of Technology, Japan

As a part of study to reveal relationship between physiological property and structure of proteins from sulfate-reducing bacteria, crystallographic structure determination of rubredoxin from Desulfovibrio vulgaris Miyazaki F (RdDvMF) has been carried out using molecular replacement method. RdDvMF has been crystalized in two forms, Form I and Form II. Form I belongs to P 3221 and Form II, P 21. Because of so small size of crystal, radiation power of ordinal conventional x-ray generators do not have enough radiation power for diffraction study, so diffraction study was carried out at Photon Factory, KEK in Japan. Diffraction data were collected using one crystal for Form I and using three crystals for Form II, respectively. Diffraction patterns were processed using Denzo and merged using Scalepack [Otwinowski, in Data Collection and Processing (eds Sawyer, L., Isaacs, N. & Bailey, S.) 56-62 (SERC Daresbury Laboratory, Warrington, 1993)]. Crystal data are as follows; One is space group P 3221, Z=6, cell parameters a=b=43.7, c=50.7Å, gamma=120, V=83849.7Å₃. The other is space group P 21, Z=6, cell parameters a=27.3, b=44.9, c=51.2Å. ß=90.6, V=62664.9Å₃. As the starting model for molecular replacement method, structure of rubredoxin from Desulfovibrio vulgaris Hildenborough (RdDvH) [Adman et al. (1991). J. Mol. Biol. 217, 337-352] was used. Final R value of Form I is 20.8% including 32 water molecules up to 2.0 Å resolution with 53.6% data completeness and that of Form II is 18.9% including 86 water molecules up to 1.9 Å resolution with 82.5% data completeness, respectively. Homology of amino acid sequences between RdDvMF and RdDvH is 90%. Molecular structure of Form I is compared with those of other rubredoxin from anaerobic bacteria. As the result essential similarity of core environment, including the structure of [Fe-4S(of Cys)] type active center, can be seen also in RdDvMF and it is considered that this similarity should be strongly related to the nature of rubredoxin as an electron carrier.