Dialysis solution: 50 mM NaH2PO4, 300 mM NaCl pH8.0

For dialysis a mini dialysis kit from Amersham Biosciences with 1kDa
cut-off was employed (product code 80-6483-94). The tubing was
prepared as indicated by the manufacturer. Dialysis was undertaken in
the cold room on a magnetic stirrer for 2 h. After dialysis enzyme
assays were carried out using the purified protein.