AKR and SDR were eluted with an elution
buffer (1 ml) containing 20 mM sodium phosphate, 500 mM NaCl,
500 mM imidazole, and 20% glycerol (pH 7.4). Elution was repeated
three times to collect 4 protein fractions (1ml each). Eluted fractions
were loaded onto Zeba™Spin Desalting Columns (Thermo Scientific)
and dialyzed against 25mM potassiumphosphate buffer (pH7.0) plus
20% glycerol following themanufacturer's protocol. Purified AKR and
SDR were stored at 20 C until further use.