Recombinant Human Cathepsin L Protein, CF

• 6 months from date of receipt, -20 to -70 °C as supplied.
• 3 months, -20 to -70 °C under sterile conditions after opening.

• Assay Buffer: 50 mM MES, 5 mM DTT, 1 mM EDTA, 0.005% (w/v) Brij-35, pH 6.0
• Recombinant Human Cathepsin L (rhCathepsin L) (Catalog # 952-CY)
• Fluorogenic Peptide Substrate VII: Z-Leu-Arg-AMC (Catalog # ES008)
• F16 Black Maxisorp Plate (Nunc, Catalog # 475515)
• Fluorescent Plate Reader (Model: SpectraMax Gemini EM by Molecular Devices) or equivalent

1. Dilute rhCathepsin L to 40 µg/mL in Assay Buffer.
2. Incubate diluted rhCathepsin L on ice for 15 minutes.
3. Dilute incubated 40 µg/mL rhCathepsin L to 0.02 ng/µL in Assay Buffer.
4. Dilute Substrate to 80 µM in Assay Buffer.
5. Load 50 µL of 0.02 ng/µL rhCathepsin L into a black well plate, and start the reaction by adding 50 µL of 80 µM Substrate. Include a Substrate Blank containing 50 µL Assay Buffer and 50 µL of 80 µM Substrate without any rhCathepsin L.
6. Read at excitation and emission wavelengths of 380 nm and 460 nm (top read), respectively, in kinetic mode for 5 minutes.
7. Calculate specific activity:

     *Adjusted for Substrate Blank

     **Derived using calibration standard 7-Amino, 4-Methyl Coumarin (AMC) (Sigma, Catalog # A-9891).

• rhCathepsin L: 0.001 µg
• Substrate: 40 µM