We have a purified metalloprotease ( serralisyn from S. marcescens) which stay alive and is able to recover activity when:

1) We heat at 72 degrees for 1 hour

2) Freeze and thaw for 30 cycles

3) Put at pH 2 or 12 for 30 minutes

To work with it, I use 30 mM EDTA. But after dialysis, it activates again and probably goes to autolysis. I would like a clue...