title: Characterization of parathyroid hormone fragments produced by cathepsin D.
abstract: Cleavage of parathyroid hormone by cathepsin D was studied. Four primary products were detected and separated by high performance liquid chromatography. Two of the fragments are fluorescent and therefore contain residue 23 (tryptophan). These fragments are NH2-terminal in origin. The other two cross-react with antisera directed against COOH-terminal portions of the hormone; they are the complementary COOH-terminal fragments. Microsequencing and amino acid analysis showed that the two COOH-terminal fragments are 35-84 and 38-84 bovine parathyroid hormone. By CNBr cleavage and amino acid analysis, the two NH2-terminal fragments were shown to be the complementary 1-37 and 1-34 fragments. The 1-37 fragment is transitory and is rapidly hydrolyzed to 1-34, so that only relatively small amounts are detected at any one time. However, 34-84 was not converted to 38-84, although cleavage at other sites in the COOH-terminal fragments was observed with more exhaustive digestion. The 1-34 fragment appears to be the final product of the action of cathepsin D on parathyroid hormone. Both enzymatically produced NH2-terminal fragments were fully active in the renal membrane adenylyl cyclase assay system.
mesh_terms: D000262:Adenylyl Cyclases / Q000378:metabolism; D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000818:Animals; D002402:Cathepsin D / Q000378:metabolism*; D002417:Cattle; D002851:Chromatography, High Pressure Liquid; D003488:Cyanogen Bromide; D004789:Enzyme Activation / Q000187:drug effects; D007668:Kidney / Q000201:enzymology; D010281:Parathyroid Hormone / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism* / Q000494:pharmacology
chemical_list: D000596:Amino Acids; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D002402:Cathepsin D; D000262:Adenylyl Cyclases; D003488:Cyanogen Bromide