Baboon (Papio ursinus) cathepsin L: purification, characterization and comparison with human and sheep cathepsin L

Theresa H T Coetzer, Kevin M. Dennehy, Robert N. Pike, Clive Dennison

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Abstract

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.

Original languageEnglish
Pages (from-to)429-439
Number of pages11
JournalComparative Biochemistry and Physiology Part B: Comparative Biochemistry
Volume112
Issue number3
DOIs
Publication statusPublished - 1 Jan 1995
Externally publishedYes

Keywords

  • Baboon
  • Cathepsin L
  • Cystatins
  • Enzyme-inhibitor complexes
  • N-terminal sequences
  • Stefins

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