4.2.1.9	-20°C, about 85% loss of activity after 4 weeks, crude extract is unstable upon storage	
4.2.1.9	-80°C, after purification of His-tagged enzyme the total enzyme activity is decreased to 43% of the crude extract and even further to 17% when stored at -80 °C for one day	
4.2.1.9	-80°C, specific activity for D-gluconate of the frozen/thawed enzyme is stable for 60 min, but loses about 70% after a maximum of 100 min