Can you please suggest how to store esterase from porcine liver for long time?

We use E3019-3.5KU. We store at -20C, but after 3-4 times of opening, the esterase in the bottle loses its activity. We aim to use it in PBS buffer 7.4. Have anyone stored esterase in PBS buffer...

11 May 2023 7,378 2 View