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P5931 Sigma-Aldrich

Phosphatase, Alkaline from Escherichia coli

lyophilized powder, 30-60 units/mg protein (in glycine buffer)

Synonym: Orthophosphoric-monoester phosphohydrolase (alkaline optimum)




Alkaline phosphatase is used for conjugation to antibodies and other proteins for ELISA, Western blotting, and histochemical detection. It may be used for protein labeling when high sensitivity is required. Product P5931 has been used during immunoblots to treat cell membranes prior to Tau1 incubation.

The enzyme from Sigma has been used to develop a synthetic nanopore membrane. This membrane mimics protein channels that are regulated by phosphorylation/dephosphorylation and uses an aligned array of carbon nanotubes (CNTs) impregnated in a polystyrene matrix.


100, 200, 500 units in glass bottle

Biochem/physiol Actions

Alkaline phosphatase, from Escherichia coli, is a dimeric, non-glycosylated protein which mainly reside in the periplasmic space. Three known isoforms exist. The enzyme requires zinc, and is activated by magnesium. E. coli akaline phosphatase has a broad specificity for phosphate esters.

The enzyme is a phosphohydrolase having an optimal pH of 10 in vitro. The actual optimum pH varies depending on the nature and concentration of the substrate, the type of buffer, the phosphate acceptor, and to some extent the nature of the isoenzymes. It catalyzes the hydrolysis of phosphate monoesters such as p-nitrophenyl phosphate, phenyl phosphate, phenolphthalein phosphate, α-glycerol phosphate, β-glycerol phosphate, 2-phosphorylglycerate, triosephosphate, glucose-6-phosphate, glucose 1-phosphate, fructose 1-phosphate, fructose 6-phosphate, adenosine 5-phosphate adenosine 3-phosphate, phosphoenolpyruvate, and β-nicotinamide adenine dinucleotide phosphate. The activity is inhibited by 1,10-phenanthroline monohydrate, diethylenetriaminepentaacetic acid, ethylene glycol-bis(2-aminoethylether)-N,N,N’,N’-tetraacetic acid, and ethylenediaminetetraacetic acid disodium salt dihydrate.

Unit Definition

One unit will hydrolyze 1.0 μmole of p-nitrophenyl phosphate per min at pH 10.4 at 37 °C.

Physical form

Lyophilized powder containing Tris buffer salts, MgSO4, and ZnSO4

Preparation Note

Chromatographically purified

Safety & Documentation

Safety Information

NONH for all modes of transport
WGK Germany 

Single- & multi-channel pipettes from BRAND
Protocols & Articles

Related Content

Enzymes & Proteins

Application Index | Enzyme Index | Substrate Index | Inhibitor Index | Cofactor Index | Lectin Index
Keywords: Cell signaling, Diagnostic, Drug discovery, Metabolomics, Molecular biology

Peer-Reviewed Papers


Related Products


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D6518 Diethylenetriaminepentaacetic acid, ≥99% (titration)
P9375 1,10-Phenanthroline monohydrate, reagent grade
E4378 Ethylene glycol-bis(2-aminoethylether)-N,N,N′,N′-tetraacetic acid, ≥97.0%
ED2SS Ethylenediaminetetraacetic acid disodium salt dihydrate, reagent grade, 98.5-101.5% (titration)


Product #


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N2770 SIGMAFAST p-Nitrophenyl phosphate Tablets, tablet, To prepare 20 mL
N1891 SIGMAFAST p-Nitrophenyl phosphate Tablets, tablet, To prepare 5 mL
M3168 4-Methylumbelliferyl phosphate (4-MUP) Liquid Substrate System, liquid

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