Crystallisation and preliminary X-ray analysis of the receptor-binding domain of human and bovineα2-macroglobulin

Abstract
The receptor-binding domains (RBDs) of human and bovine α 2 -macroglobulin ( α 2 M) have been isolated after limited proteolysis of methylamine-treated α 2 M with papain. Single crystals of the RBDs have been grown by vapour diffusion. Crystals of human RBD are very thin plates unsuited for data collection. However, crystals of RBD from bovine α 2 M give diffraction patterns suitable for X-ray analysis, and a complete dataset with a maximum resolution of 2.3 Å has been collected with synchrotron radiation at cryogenic temperature. The crystals belong to spacegroup P3 1 21 or P3 2 21 with cell parameters a = b = 106.8 A ̊ , c = 72.2 A ̊ .