1.14.13.5 -20°C, potassium phosphate buffer, pH 7.2, no loss of activity for at least 1 month 1.14.13.5 -20°C, stable for at least 6 months 1.14.13.5 4°C, 5-100 mM potassium phosphate buffer, pH 7.2, almost full activity retained for several days