title: Procathepsin D cannot autoactivate to cathepsin D at acid pH.
abstract: The amino acid sequence of the propart of bovine procathepsin D was determined at the protein level. Incubation of the isolated procathepsin D at pH 3.5-5.0 for 30-120 min leads to a 2 kDa reduction in its molecular mass, as seen by SDS-PAGE. The activation product is pseudocathepsin D and is the result of a proteolytic cleavage between LeuP26 and IleP27 in the propart. Incubation at pH 5.0 for 20 h of either procathepsin D or pseudocathepsin D results in both cases in approximately equal amounts of pseudocathepsin D and a further processed intermediate, nine amino acids shorter than pseudocathepsin D. No reaction products corresponding to cathepsin D with a mature amino terminus were observed, showing that autoproteolysis alone cannot generate the mature form found in the lysosomes.
authors.affiliation: Department of Molecular Biology, University of Aarhus, Denmark.
authors.forename: L B
authors.initials: LB
authors.lastname: Larsen
authors.forename: A
authors.initials: A
authors.lastname: Boisen
authors.forename: T E
authors.initials: TE
authors.lastname: Petersen
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D002402:Cathepsin D / Q000737:chemistry / Q000378:metabolism*; D002417:Cattle; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases / Q000378:metabolism; D004789:Enzyme Activation; D004792:Enzyme Precursors / Q000737:chemistry / Q000378:metabolism*; D006863:Hydrogen-Ion Concentration; D008892:Milk / Q000201:enzymology; D008894:Milk Proteins / Q000737:chemistry; D008969:Molecular Sequence Data; D008970:Molecular Weight
chemical_list: D004792:Enzyme Precursors; D008894:Milk Proteins; D010450:Endopeptidases; C058345:procathepsin D; D002402:Cathepsin D