Partial Purification and Some Properties of Thyroid Peroxidase Solubilized by Alkaline Treatment

Abstract

Thyroid peroxidase from frozen porcine thyroids has been solubilized by suspension of thyroid “microsomes” in pH 10.5, 0.05 Mcarbonate buffer and centrifugation at 105, 000 × g for 1 hr at 4°C. About 65% of the initial activity is present in the supernatant. Partial purification of the alkaline solubilized TP0 has been achieved bv DEAE cellulose chromatography and ammonium sulfate fractionation. The method results in an 18 to 20 fold purification over the homogenate and recovery of 35 to 40% of TP0 activity. Over 90% of the phospholipids present in the particulate fraction and most of the nucleic acids have been removed. The partially purified preparation catalyzes the oxidation of guaiacol and the lodination of monoiodotyrosine. It is retarded on Sephadex G-200 and has an apparent molecular weight of about 350, 000.