Purification and characterization of recombinant human cathepsin E.

The human cathepsin E was purified from the culture supernatant of Pichia pastoris strain transformed with a human cathepsin E expression plasmid. Purification was performed by a three-step procedure, TSKgel Phenyl-5PW, Toyopearl HW55S and TSKgel DEAE-5PW column chromatographies. The purified recombinant cathepsin E had the molecular mass of around 82-kDa with the amino-terminal sequence started with Ile37 of the predicted amino acid sequence, suggesting the human cathepsin E was accumulated in the culture suparnatant as the mature dimer enzyme. The result of endoglycosidase-H digestion followed by Western blot analysis of the purified recombinant cathepsin E suggested that the human cathepsin E expressed in Pichia pastoris received N-linked high-mannose type glycosylation.