PURIFICATION AND CRYSTALLIZATION OF THE AUTOANTIGEN THYROID PEROXIDASE FROM HUMAN GRAVES THYROID-TISSUE

Milligram quantities of the human membrane autoantigen thyroid peroxid ase (TPO) have been purified to a high degree of homogeneity by a comb ination of detergent solubilisation, monoclonal antibody affinity, and ion exchange chromatography, from pooled Graves' disease thyroid glan ds. The purified TPO of greater than 90% purity was enzymatically acti ve as judged by its ability to oxidise guaiacol. Crystals of TPO have been grown from solutions of the protein solubilised in sodium deoxych olate, in the presence of ammonium sulphate. The crystals exhibited bi refringence under polarised light, indicative of molecular order. Crys tallisation of this large, membrane autoantigen represents the first s tep in delineating the complete three-dimensional structure of a human autoantigen involved in destructive thyroiditis. (C) 1997 Academic Pr ess.