Thyroid acid protease

Chymosin, bovine Cathepsin D, spleen Cathepsin E, bone marrow Thyroid acid protease... 

Sample preparation Weigh out powder equivalent to about 65 mg thyroid, add 5 mL enzyme solution, mix well, incubate at 37° for 28 h, agitate after 4-8 h and after 20-24 h, add 2 mL deactivating solution, mix well, centrifuge at 2000 rpm for 5-10 min, if necessary filter (0.45 pm). (The enzyme solution was about 150 protease units/mL of bacterial protease from Streptomyces griseus in 110 mM NaCL + 40 mM Tris buffer + 50 mM meth-imazole (pH adjusted to 8.4 0.05 with 6 M HCl) reducing buffer. Deactivating solution was 1 100 phosphoric acid MeCN.)... 

Other successful homology models have been used in docking applications and have successfully resulted in the discovery of novel hits, include retinoic acid receptor (112). thyroid hormone receptor (113). CK2 kinase (114). SARS (severe acute respiratory syndrome) protease (115). CDK4 kinase (116). and SrC SH2 (117) for the application of de novo design methods (117). 

Although shown as a sequential reaction, the iodination and coupling reactions occur simultaneously via TPO and hydrogen peroxide. Hydrogen peroxide is generated by a NADPH/FAD thyroid oxidase (THOX) at the apical membrane. Low plasma levels for T4 cause the iodinated TG to be resorbed into the follicular cell, where complete proteolysis occurs by lysosomal protease to T4, T3, DIT, MIT, and noniodinated amino acids. Both T4 and T3 are secreted by the cell into the blood T4 is deiodinated to active T3. Both DIT and MIT are recycled by a dehalogenase (or deiodinase) to free tyrosine and iodide, both of which are recycled back into iodinated thyroglobulin. 

---