2.5.1.10	-20°C, at least 1 week, no loss of activity	
2.5.1.10	-80°C, 3 months, no loss of activity	
2.5.1.10	4°C, 5 days, 36% loss of activity	
2.5.1.10	4°C, precipitate in neutral (NH4)2SO4 solution at 60% saturation, 1 year, 50-70% loss of activity