Dissolves readily at 5 mg/mL in a 0.025M glychine/NaOH pH 9.6 containing 1 mM magnesium chloride, 0.1 mM zinc chloride and 10% glycerol, to give a clear pale pink solution also soluble in distilled water or dilute buffer.
One unit liberates one µmole of p-nitrophenol per minute at 37 °C, pH 10.15 in Tris buffer. The enzyme activity is determined by measuring the increase in optical density at 405 nm resulting from the hydrolysis of p-nitrophenyl phosphate.
Activators: Zn, Mg2+, Ca2+, Tris buffer, diethanolamine; Inhibitors: Acidification to pH 4.5 reversibly inactives the enzyme; inorganic phosphate, chelating agents such as EDTA. Note: Alkaline phosphatase is fully active in the presence of sodium azide (0.05%) and Triton X-100 (0.1%).
Alkaline phosphatase is used for removing phosphate monoester to prevent self ligation. It can be also be used as a label for enzyme immunoassays.
