1.2.1.31	addition of 10 mM 2-mercaptoethanol and protease inhibitors e.g.: 5 mM EDTA, 1 mM phenylmethylsulfonyl fluoride to the crude extract improves stability	
1.2.1.31	freezing-thawing, frozen enzyme loses 10-20% of activity during each freeze-thaw cycle	
1.2.1.31	low ionic strength: unstable	
1.2.1.31	lyophilization inactivates