Evaluation of the (haem)Fe--Nepsilon(2)(HisF8) bond distances from haemoglobin structures deposited in the Protein

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Structure and Coordination Determination of Peptide-metal Complexes Using 1D and 2D 1H NMR

Published on: December 16, 2013

Flavio Augusto Vicente Seixas1, Talita Dala Santini, Vanessa Pereira de Moura

  • 1Technology Center, State University of Maringá, UEM, Brazil. favseixas@uem.br

Acta Crystallographica. Section D, Biological Crystallography
|August 16, 2008
PubMed

Scientists working on the structure and function of proteins use haemoglobin as a model of allosteric proteins. In this molecule, the (haem)Fe-N(2)(His) bond is one of the most significant because the length of this bond provides relevant information about the mechanism of cooperativity and affinity for O(2). Thus, the aim of the present study was to evaluate the quality of the structural models of Hb deposited in the Protein Data Bank (PDB), in particular the reliability of the Fe-N(2) bond distance. To achieve this, 329 Hb structures solved by X-ray diffraction were downloaded from the PDB. The Fe-N(2) bond distance was computed and compared with the ideal value determined using the spectroscopic techniques of X-ray absorption and EXAFS. This investigation showed the presence of crystallographic structures of native haemoglobins deposited in the PDB in which the Fe-N(2) bond distance was far beyond the ideal value found for this length, a fact that makes their use in studies that correlate haemoglobin structure and function questionable.

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