Recombinant Mouse Iduronate 2-sulfatase 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 NaOAc, pH 5.0
• Recombinant Mouse Iduronate 2‑Sulfatase/IDS (rmIDS) (Catalog # 2486-SU)
• Substrate: 4-Nitrocatechol Sulfate (4-PNCS) (Sigma, Catalog # N-7251)
• Sodium Hydroxide (NaOH) (Sigma, Catalog # S-0899)
• 96-well Clear Plate (Costar, Catalog # 92592)
• Plate Reader (Model: Spectra-Max Plus by Molecular Devices) or equivalent

1. Dilute rmIDS to 20 µg/mL in Assay Buffer.
2. Dilute Substrate to 2 mM in Assay Buffer.
3. Combine 150 µL of 20 µg/mL rmIDS and 150 µL of 2 mM Substrate. Include a Substrate Blank containing Assay Buffer and Substrate only.
4. Incubate at 37 °C for 24 hours.
5. Stop reaction by adding 300 µL of 0.2 M NaOH to reaction tubes.
6. Load 200 µL from each reaction tube in duplicate into a plate.
7. Read at 510 nm (absorbance) in endpoint mode.
8. Calculate specific activity:

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

• rmIDS: 1.0 µg
• Substrate: 1 mM