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N7653 Sigma

p-Nitrophenyl Phosphate Liquid Substrate System


Synonym: 4-Nitrophenyl phosphate disodium salt solution, pNPP



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Substrate for alkaline phosphatase that yields a soluble yellow end product that may be read at 405 nm. The reaction may be stopped with 3N NaOH and read at 405 nm. Recommended for ELISA (microwell) procedures, not recommended for membrane applications.


Stable at least one year when stored below 0 °C.

Physical form


General description

The p-Nitrophenyl Phosphate (pNPP) Liquid Substrate System combines p-nitrophenyl phosphate, buffer, and the required magnesium cations in a convenient, ready-to-use, single solution reagent. Producing a soluble end product, pNPP is the substrate of choice in alkaline phosphatase enzyme immunoassays.1

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Protocols & Articles


Antibody Basics

Immunoglobulins (Igs) are produced by B lymphocytes and secreted into plasma. The Ig molecule in monomeric form is a glycoprotein with a molecular weight of approximately 150 kDa that is shaped more ...
Keywords: Affinity chromatography, Centrifugation, Chromatography, Digestions, High performance liquid chromatography, Ion Exchange, Microscopy, Precipitation, Purification, Scanning electron microscopy

Colorimetric Alkaline Phosphatase and Peroxidase Substrate Detection Systems

Nitroblue Tetrazolium (NBT) is used with the alkaline phosphatase substrate 5-Bromo- 4-Chloro-3-Indolyl Phosphate (BCIP) in western blotting and immunohistological staining procedures. These substrat...
BioFiles 2008, 3.4, 6.
Keywords: Applications, Enzyme-linked immunosorbent assay, Formulations, Immunohistochemistry, Western blot

High Throughput Screening of Peptide Substrates for Tyrosine Kinases

Protein Tyrosine Kinases (PTKs) play important roles in modulating a wide variety of cellular events, including differentiation, proliferation, metabolism, and apoptosis. Therefore, identification of...
Keywords: Apoptosis, Enzyme-linked immunosorbent assay, Events, Infrared spectroscopy, Metabolism, Methods, Peptide synthesis, Phosphorylations, Sequences

High-throughput Screening of Peptide Substrates for Tyrosine Kinases Using PEPscreen® Custom Peptide Library

Protein Tyrosine Kinases (PTKs) play important roles in modulating a wide variety of cellular events, including differentiation, proliferation, metabolism and apoptosis. Those regulations are mediate...
Danhui Wang, Fan Zhang, Tao Zhao, Fei Zhong, Keming Song
Keywords: Apoptosis, Enzyme-linked immunosorbent assay, Events, Metabolism, Methods, Peptide synthesis, Pharmaceutical, Phosphorylations, Sequences

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Antibody Explorer - Over 80,000 Products

Monoclonal and polyclonal primary antibodies are focused on cell biology, neurobiology and molecular biology. Secondary antibodies targeting multiple host’s IgG are conjugated to alkaline phosphatase...
Keywords: Buffers, Cancer, Cell biology, Enzyme-linked immunosorbent assay, Immunohistochemistry, Immunoprecipitation, Molecular biology, Neuroscience, Phosphorylations, Purification, Western blot

Peer-Reviewed Papers


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1. A substrate amplification system for enzyme-linked immunoassays. II. Demonstration of its applicability for measuring anti-DNA antibodies. Jones JV, Mansour M, James H, et al. J. Immunol. Methods 118(1), 79-84, (1989)


Topological Analysis Of A Haloacid Permease Of A Burkholderia Sp. Bacterium With A PhoA-LacZ Reporter. Tse, Y.M., et al. BMC Microbiol. 9, 233, (2009)


Plasmodium vivax sub-patent infections after radical treatment are common in Peruvian patients: results of a 1-year prospective cohort study. Van den Eede P, Soto-Calle VE, Delgado C, et al. PLoS ONE 6(1), e16257, (2011)


Glycan microarray of Globo H and related structures for quantitative analysis of breast cancer. Wang CC, Huang YL, Ren CT, et al. Proc. Natl. Acad. Sci. U. S. A. 105(33), 11661-6, (2008)


BMP-13 emerges as a potential inhibitor of bone formation. Shen B Int. J. Biol. Sci. 5(2), 192-200, (2009)


Dengue virus neutralization by human immune sera: role of envelope protein domain III-reactive antibody. Wahala WM Virology 392(1), 103-13, (2009)


Spatial distribution and expression of intracellular and extracellular acid phosphatases of cluster roots at different developmental stages in white lupin. Tang H, Li X, Zu C, et al. J. Plant Physiol. 170(14), 1243-50, (2013)


Trypanosoma rangeli: an alkaline ecto-phosphatase activity is involved with survival and growth of the parasite. Dos-Santos AL, Dick CF, Silveira TS, et al. Exp. Parasitol. 135(2), 459-65, (2013)


Site-directed mutagenesis maps interactions that enhance cognate and limit promiscuous catalysis by an alkaline phosphatase superfamily phosphodiesterase. Wiersma-Koch H, Sunden F, and Herschlag D Biochemistry 52(51), 9167-76, (2013)


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