Purification, crystallization and preliminary X-ray analysis of haemoglobin I from the armoured catfish Liposarcus anisitsi

Liposarcus anisitsi is an armoured catfish that presents accessorial air ox ygenation through a modified stomach, which allows this species to survive in waters with very low oxygen content. Analysis of its haemolysate has sho wn the presence of four haemoglobins; this work focuses on the main compone nt, haemoglobin I. It has been crystallized in two different forms and X-ra y diffraction data have been collected to 2.77 and 2.86 Angstrom resolution using synchrotron radiation. Crystals were determined to belong to the spa ce groups C2 and P2(1) and preliminary structural analysis revealed the pre sence of one tetramer in the asymmetric unit in both crystal forms. The str ucture was determined using a standard molecular-replacement technique.