Location of haem in bacterioferritin of E. coli

Acta Crystallogr D Biol Crystallogr. 1993 Nov 1;49(Pt 6):597-600. doi: 10.1107/S0907444993007073.

Abstract

. A low-resolution partial structure of bacterioferritin was solved using a combination of molecular replacement and rigid-body refinement methods. Modification of bacterioferritin crystals by soaking in tetrachloroplatinate results in a phase transition from tetragonal symmetry (space group P4(2)2(1)2) to a pseudo-cubic one (approximate space group I432). Helical parts of human H ferritin structure stripped of side chains beyond the C(beta) atoms were used as the model. An electron-density map of the refined model revealed a region of extended density which by its shape and position in a pocket between helices was identified as haem. Inclusion of haem in the refinement showed that it can occupy only one of two symmetry-related sites near a twofold axis of the molecule.