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Alkaline Phosphatase (AP)

grade I, from calf intestine

Enzyme Commission number:

Quality Level



specific activity

~2000 units/mg protein (At 37 °C with 4-nitrophenyl phosphate as the substrate, and diethanolamine as the buffer (400 U/mg at 25 °C with 4-nitrophenyl phosphate as the substrate, and glycine as the buffer))


pkg of 1,500 U (10108138001)
pkg of 7,500 U (10108146001)

optimum pH



7.6 at 278 nm (10 mg AP/ml)

shipped in

wet ice

storage temp.


General description

Orthophosphoric-monoester phosphohydrolase (alkaline optimum)
Alkaline phosphatase catalyzes the removal of phosphate group from various compounds that are phosphorylated. It hydrolyzes 5′-monophosphate groups from both DNA and RNA. It can also hydrolyze 5′-diphosphate and 5′-triphosphate groups from RNA.


Heat inactivation: AP activity is destroyed irreversibly by incubating the enzyme at 65 °C.
Denaturation is dependent on protein concentration - using less than 10 U/ml (0.1 mol/l glycine buffer, pH 10.5, 1 mmol/l MgCl2 and 0.1 mmol/l ZnCl2), AP is inactivated by a 10 minutes incubation at 65 °C.


Selective cleavage of terminal phosphate groups from oligonucleotides and in protein nucleotide exchange and deliverance. It has also been used to phosphorylate samples to distinguish between phosphate moieties present as phosphorylated glycans and phosphorylated amino acid residues.


Contaminants: <0.0004% PDE, <0.004% ADA and A-5-MP deaminase, each


AP is a dimer of identical or nearly identical subunits; each of which contains 2 molecules of Zn2+ , one tightly bound and necessary for structural stability, the other loosely bound and required for caytalytic activity. The active site contains a reactive serine.
In some mammals (e.g., humans), there are at least 3 distinguishable isoenzymes: the intestinal, the placental and the form found in bone/liver/kidney.

Unit Definition

Unit Conversion: 1 Roche unit (tested at +25 °C) corresponds to ~2 to 2.5 Sigma units (tested at +37 °C).
AP activity is not expressed in Armstrong units; a conversion factor for international units is not known.
Approx. 3.8 U (grade I AP) or 4.0 U (grade II AP) [+37 °C, 4-NPP as substrate, diethanolamine as buffer, pH 9.8] = 1 U [+25 °C, 4-NPP as substrate, glycine as buffer, pH 10.5].

Biochemica Information. 87 (grade I AP) :
1.0 U [+37 °C, QC assay conditions] = 0.79 U [+30 °C, QC assay conditions] = 0.57 U [+25 °C, QC assay conditions]

Physical form

Suspension in 3.2 M ammonium sulfate solution, 1 mM MgCl2, 0.1 mM ZnCl2, pH approximately 7

Preparation Note

  • Activator: Divalent metal ions (Mg2+, Co2+, Mn2+)
  • Amino alcohols (2-amino-2-methyl-1-propanol, diethanolamine)

Note that high concentrations of amino alcohols can as well act as competitive inhibitors (e.g., monoethanolamine in diethanolamine).

Storage conditions (working solution): The suspension is offered at a c= approx. 5 mg/ml.
If this suspension is diluted only 5 to 10-fold with further 3.2 M ammonium sulfate solution, 1 mM MgCl2, 0.1 mM ZnCl2, pH approx. 7, we would expect from general experience that a stability for some weeks might be given provided it is stored at 4 °C (no guarantee!).

Other Notes

For life science research only. Not for use in diagnostic procedures.

Storage Class Code

12 - Non Combustible Liquids



Flash Point(F)

does not flash

Flash Point(C)

does not flash

Certificate of Analysis

Certificate of Origin

Stephanie Ketcham
Biotechniques, 117-123 (2017)
Raphael Gasper et al.
Small GTPases, 1(3), 133-141 (2011-06-21)
The Ras family is the largest and most diverse sub-group of Ras-like G proteins. This complexity is further increased by the high number of regulatory Guanine nucleotide Exchange Factors (GEFs) and GTPase Activating Proteins (GAPs) that target specific members of...
O Brenna et al.
The Biochemical journal, 151(2), 291-296 (1975-11-01)
A crude preparation of alkaline phosphatase (EC from calf intestinal mucosa was purified by affinity chromatography on Sepharose-bound derivatives of arsanilic acid, which was found to be a competitive inhibitor of the enzyme. Three biospecific adsorbents were prepared for...
Brian M Zeglis et al.
Nature protocols, 2(2), 357-371 (2007-04-05)
This protocol describes the syntheses and applications of two metallointercalators, Rh(bpy)2(chrysi)3+ and Rh(bpy)2(phzi)3+, that target single base mismatches in DNA. The complexes bind mismatched DNA sites specifically and, upon photoactivation, promote strand scission neighboring the mismatch. Owing to their high...


Alkaline Phosphatase (AP) Protocol

Alkaline Phosphatase (AP) Protocol

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