title: Parathyroid hormone-degrading enzyme of high molecular weight in the cytosol of rat renal cortical cells.
abstract: Using unlabeled bovine parathyroid hormone (b-PTH) as the substrate, the PTH-degrading activity in the 100,000 x g supernatant of rat renal cortex was examined. The PTH-degrading activity showed the highest peak at pH 7.25, along with 3 minor peaks at pH 4.5, 6.0 and 8.5. The neutral PTH-degrading activity of the 100,000 x g supernatant (pH 7.25) was eluted at V0 in Sephadex G-200 gel filtration corresponding to a high molecular weight. The neutral PTH-degrading activity was inhibited by ATP and calcium, but the acid PTH-degrading activity (pH 4.5) was slightly activated by ATP and was uninfluenced by calcium. The cytosolic neutral PTH-degrading activity was not inhibited by PMSF, trypsin inhibitor, E-64, chymostatin, leupeptin or pepstatin, whereas the acid PTH-degrading activity was inhibited by pepstatin, leupeptin, trypsin inhibitor and chymostatin. The neutral and acid PTH-degrading activities most probably depend on different enzymes. The neutral PTH-degrading enzyme is unlike any of the PTH-degrading enzymes so far reported.
mesh_terms: D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D003600:Cytosol / Q000378:metabolism; D004798:Enzymes / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D007672:Kidney Cortex / Q000378:metabolism*; D008297:Male; D008970:Molecular Weight; D010281:Parathyroid Hormone / Q000378:metabolism*; D011500:Protein Synthesis Inhibitors / Q000494:pharmacology; D051381:Rats; D011919:Rats, Inbred Strains
chemical_list: D004798:Enzymes; D010281:Parathyroid Hormone; D011500:Protein Synthesis Inhibitors; D000255:Adenosine Triphosphate