Baboon (Papio ursinus) cathepsin L: purification, characterization and comparison with human and sheep cathepsin L.
Cathepsin L was purified from the liver of a higher primate, the baboon (Papio ursinus), largely in a single-chain form and in the form of proteolytically active complexes with an endogenous cystatin. This mimics the situation found in both human and sheep livers. Both forms of cathepsin L were active at physiological pH. Physicochemical characterization and N-terminal amino sequencing of baboon cathepsin L showed a close relationship with the human enzyme. Cystatins with characteristics similar to those found for stefins A and B could also be purified from baboon livers. Proteolytically active, SDS-stable complexes could be shown to form in vitro with the molecules characterized as stefin B, but not with stefin A type cystatins. The non-inhibitory complexes could be shown to require less cysteine for activation than free cathepsin L and this, together with the above result, might indicate that a sulfhydryl interchange mechanism is responsible for the formation of covalent, non-inhibitory complexes.
Department of Biochemistry, University of Natal, Scottsville, Pietermaritzburg, South Africa.
T H
TH
Coetzer
K M
KM
Dennehy
R N
RN
Pike
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C
Dennison
D000818:Animals; D056668:Cathepsin L; D002403:Cathepsins / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D055313:Cystatin B; D015891:Cystatins / Q000378:metabolism; D003546:Cysteine Endopeptidases; D015853:Cysteine Proteinase Inhibitors / Q000378:metabolism; D004591:Electrophoresis, Polyacrylamide Gel; D010450:Endopeptidases; D006801:Humans; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008099:Liver / Q000201:enzymology*; D010215:Papio; D010446:Peptide Fragments / Q000737:chemistry; D017421:Sequence Analysis; D012756:Sheep
C524994:CSTB protein, human; D015891:Cystatins; D015853:Cysteine Proteinase Inhibitors; D010446:Peptide Fragments; D055313:Cystatin B; D002403:Cathepsins; D010450:Endopeptidases; D003546:Cysteine Endopeptidases; C534281:CTSL protein, human; D056668:Cathepsin L