2.7.7.33	-18°C, in EDTA-containing Tris-HCl buffer, at least 1 year	
2.7.7.33	-20°C, about 30% loss of activity within 1 month	
2.7.7.33	-80°C stable for months with no loss of activity, freezing and thawing does not affect the enzyme activity	
2.7.7.33	4°C stable for days	
2.7.7.33	frozen, 2-3 months stable