title: Crystallographic analysis of the three-dimensional structure of baboon alpha-lactalbumin at low resolution. Homology with lysozyme.
abstract: The crystal structure of baboon alpha-lactalbumin has been determined at 6 A and at 4.5 A (0.6 nm and 0.45 nm) resolution by the method of isomorphous replacement. The principal derivative was prepared by reducing a disulphide bridge in the crystals and inserting a mercury atom. Detailed comparison of the electron-density maps with corresponding maps of hen egg-white lysozyme shows that they are closely similar, with correlation coefficients of 0.57 and 0.44 at 6 A and 4.5 A resolution respectively. This result, in accordance with earlier predictions based upon comparisons of amino-acid sequences, provides further evidence that class C lysozymes and alpha-lactalbumins are homologous proteins and it is in keeping with the hypothesis that the alpha-lactalbumins evolved from a lysozyme precursor.
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D007768:Lactalbumin; D008958:Models, Molecular; D009113:Muramidase; D010215:Papio; D011487:Protein Conformation; D014961:X-Ray Diffraction
chemical_list: D007768:Lactalbumin; D009113:Muramidase