Improved method of thyroid peroxidase extraction from the human thyroid gland.

This study describes a new method of solubilizing thyroid peroxidase (TPO) and partial purification of TPO from a small surgical specimen of human thyroid tissue. Graves' thyroid tissue was homogenized and centrifuged to obtain the 100 000 X g pellet. To solubilize TPO from the 100 000 X g pellet protein, the following four detergents were used: Triton X-100, digitonin, sodium deoxycholate, and 3-[(3-choramidpropyl)-dimethylammonio] 1-propanesulfate (CHAPS). For some samples, two detergents were combined and trypsin was also used. The best solubilization of TPO activity was obtained from the combination of digitonin-CHAPS-trypsin treatment or deoxycholate-CHAPS-trypsin treatment. The solubilized crude TPO was then chromatographed on a Sephacryl S 300 column. The results of chromatography indicated that detergent treatment alone did not separate TPO from other membrane proteins and the addition of trypsin was required for separation of TPO. Sephacryl chromatography of detergent-trypsin solubilized TPO was suitable as an initial step for purification of TPO from a small human thyroid tissue.