4.1.1.18	-20°C, crude extract, stable for months	
4.1.1.18	-80°C, stable for one month in presence of 20% glycerol, loss of activity within 2 weeks without glycerol	
4.1.1.18	0-4°C,50% loss of activity within 24 h	
4.1.1.18	4°C, 0.01 M potassium phosphate buffer, pH 6.2, 0.01 mM pyridoxal 5'-phosphate, stable for several weeks