CRYSTAL STRUCTURE OF OXYLEGHEMOGLOBIN AT 1.7 Å RESOLUTION

E. G. ARUTYUNYAN, T. N. SAFONOVA, G. V. OBMOLOVA, A. V. TEPLYAKOV, A. N. POPOV, A. A. RUSAKOV, S. V. RUBINSKY, I. P. KURANOVA, B. K. VAINSHTEIN

A. V. Shubnikov Institute of Crystallography, Academy of Sciences of the USSR, Moscow

Abstract: The structure of oxyleghemoglobin (Lb02) from yellow lupin has been determined by X-ray diffraction at 1.7 Å resolution in the atmosphere of argon at -20°C. The atomic model was refined by a restrained parameter least-square procedure to R-factor of 0.15. The O-O-Fe angle is 81°, distances from Fe to ligand atoms are 2.00 and 2.17 Å, occupancies of the ligand atoms are 0,4 and 0,5 (the low occupancies are probably due to the disorder of the oxygen molecules). Transition of Lb from deoxy- to oxy-form causes the shift of Fe in the direction of the proximal histidine His F11 (the distance between Fe and the home plane is 0.30 Å). The observed shift is opposite to that found in complexes of Lb with CO and NO. Oxygenation leads to the 70° rotation of the His F11 imidazole ring, thus breaking the hydrogen bond between N^δ1 His F11 and O Leu F7. The model includes 254 water molecules. The structure-function relations in Lb are discussed.

Russian Journal of Bioorganic Chemistry 1990, 16 (3):293-302

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