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Application

Active human cathepsin B is useful for the study of enzyme kinetics, screening inhibitors, and selectivity profiling. Active human cathepsin B has been used in a study to assess maturation through proenzyme activation and proteolytic processing. Active human cathepsin B has also been used in a study to prepare a catalytically active version from its precursor expressed in Escherichia coli in the form of inclusion bodies.

Cathepsin B Active human has been used as a supplement in serum free media for the treatment of MDA-MB-231 cell line. It has also been used as a component in low pH buffer for collagen II and complement 3 processing.

Biochem/physiol Actions

Cathepsin B Active human primarily is a preproenzyme, glycosylated on rough endoplasmic reticulum. Processing of procathepsin B to a 31 kDa, single chain active form occurs in the lysosome. It is further processed to double chain form with a 25/26 kDa heavy chain and 5 kDa heavy chain in lysosome. Cathepsin B, functions as an exopeptidase at low pH. At higher pH in endosomes or neutral pH, cathepsin B functions as endopeptidase. Cathepsin B expression is upregulated in malignant tumors and facilitates tumor invasion. Cathepsin B might reduce the production of amyloid-β peptide associated with Alzheimerβs disease. It also plays a key role in neuroprotective functions.

General description

Human cathepsin B (GenBank Accession No. NM_001908), CD33 signal peptide(amino acids 1-16) + Cathepsin B (amino acids 18-339), with C-terminal HIS tag, MW = 43 kDa, expressed in FreeStyle 293-F cells. Cathepsin B is a cysteine protease, found in the lysosome of normal cells and tissues. Cathepsin B active human is encoded by the gene CTSB, located on human chromosome 8p23.1.

Legal Information

FreeStyle is a trademark of Invitrogen Corp.

Physical form

Formulated in 40 mM Tris-HCl, pH 8.0, 110 mM NaCl, 2.2 mM KCl, 3 mM DTT, 20% glycerol, and 200 mM imidazole.

Preparation Note

Thaw on ice. Upon first thaw, briefly spin tube containing enzyme to recover full content of the tube. Aliquot enzyme into single use aliquots. Store remaining undiluted enzyme in aliquots at -70°C. Note: Enzyme is very sensitive to freeze/thaw cycles.

Unit Definition

One unit is defined as the amount of enzyme that will cleave 1 pmol of substrate per min at 37°C