Crystallization, preliminary X-ray analysis and molecular-replacement solution of the carboxy form of haemoglobin I from the fish Brycon cephalus

Haemoglobin, the `honorary enzyme' [Brunori (1999), Trends Biochem. Sci. 24, 158–161], constitutes a prime prototype for allosteric models. Here, the crystallization and preliminary X-ray analysis of haemoglobin I from the South American fish Brycon cephalus are reported. X-ray diffraction data have been collected to 2.5 Å resolution using synchrotron radiation (LNLS). Crystals were determined to belong to the space group P6₁22 and preliminary structural analysis revealed the presence of one dimer (αβ) in the asymmetric unit. The structure was determined using standard molecular-replacement techniques.