Purification, crystallisation and preliminary X-ray study of haemoglobin from Crocodilis palustris and Crocodilis porosus

The unsolved three-dimensional structure of crocodile haemoglobin and its p rospects as a blood substitute have led us to initiate the purification and crystallisation of haemoglobin molecules from crocodile species (Crocodili s palustris or mugger and Crocodilis porosus or salt water crocodile). The work has resulted in the prevention of polymerisation of naked haemoglobin molecules using N-ethylmaleimide or iodoacetamide. The purified monomeric h aemoglobin molecule of C. porosus was crystallised in two different forms a nd X-ray diffraction data were collected up to 2 Angstrom resolution for bo th forms. Form I: a = 53.62, b = 53.55, c = 103.77 Angstrom; beta = 93.35 d egrees, space group P2(1), Z = 2. Form II: a = 71.30, b = 54.70, c = 80.00 Angstrom, beta =106.4 degrees, space group P2(1), Z = 2. Structure solution and rigid body refinement of form I data resulted in a model with R-tree = 0.42 and R = 0.35. (C) 2000 Elsevier Science B.V. All rights reserved.