Crystallization, preliminary X-ray analysis and molecular-replacement solution of haemoglobin-II from the fish matrinxã (Brycon cephalus).

Haemoglobins constitute a set of proteins with interesting structural and functional properties, especially when the two large animal groups reptiles and fishes are focused on. Here, the crystallization and preliminary X-ray analysis of haemoglobin-II from the South American fish matrinxã (Brycon cephalus) is reported. X-ray diffraction data have been collected to 3.0 A resolution using synchrotron radiation (LNLS). Crystals were determined to belong to space group P2(1) and preliminary structural analysis revealed the presence of two tetramers in the asymmetric unit. The structure was determined using the standard molecular-replacement technique.