COMPARISON OF THE X-RAY STRUCTURE OF BABOON ALPHA-LACTALBUMIN AND THE TERTIARY PREDICTED COMPUTER-MODELS OF HUMAN ALPHA-LACTALBUMIN

The previously predicted structures of human alpha-lactalbumin by homology with hen egg white lysozyme by an automatic method, after the alignment stage, are compared to the X-ray determined structure of baboon alpha-lactalbumin. The root mean square by rotation method (RMSR) deviations for 122 C-alpha atoms between the two models and the X-ray structure are 2.0 angstrom and 2.3 angstrom. The RMSR deviations for all atoms, except for differences in human and baboon sequences, are 2.8 angstrom and 3.1 angstrom. If the flexible C-terminus (residues 112-122) are removed then these RMSR deviations are reduced to 2.4 angstrom and 2.3 angstrom respectively. These results are consistent with the fact that the RMSR deviation between the human and baboon X-ray structures increases from residue 112 onwards and is conformationally flexible.