Recombinant Mouse Arylsulfatase A/ARSA 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 Sodium Acetate, pH 5.0
• Recombinant Mouse Arylsulfatase A/ARSA (rmARSA) (Catalog # 2858-SU)
• Substrate: 4-Nitrocatechol Sulfate (PNCS) (Sigma, Catalog # N-7251), 100 mM stock in diH2O
• 0.2 M Sodium Hydroxide
• 96-well Clear Plate (Costar, Catalog # 92592)
• Plate Reader (Model: SpectraMax Plus by Molecular Devices) or equivalent

1. Dilute rmARSA to 20 µg/mL in Assay Buffer.
2. Dilute Substrate to 2 mM in Assay Buffer.
3. Combine in triplicate 75 µL of 20 µg/mL rmARSA and 75 µL of 2 mM Substrate. Include a Substrate Blank containing Assay Buffer in place of rmARSA.
4. Incubate reactions for 30 minutes at 37 °C.
5. Stop reactions by adding 150 µL 0.2 M sodium hydroxide to each for a final concentration of 0.1 M sodium hydroxide per reaction.
6. Load into a clear 96-well plate 200 µL from each reaction vial.
7. Read at 510 nm (absorbance) in endpoint mode.
8. Calculate specific activity:

     *Adjusted for Substrate Blank
     **Derived using calibration standard 4-Nitrocatechol (PNC) (Sigma, Catalog # N15553).

• rmARSA: 1 µg
• Substrate: 0.5 mM