Part:BBa_K1216001
Alkaline Phosphatase (phoA) from Citrobacter
The alkaline phosphatase is a periplasmic homodimeric hydrolase. Each monomer contains 429 amino acids.A form of this protein with added TEV and poly-HIS tags can be found here.
Usage and Biology
Alkaline phosphatases are used as reporter enzymes in different assays such as Western Blotting and in situ hybridization[1]. Testing human blood for Alkaline Phosphatase levels is a routine test that can reveal different conditions[2].
Alkaline phosphatases cleave phosphate groups from organic compounds by hydrolysis while retaining stereochemistry[3].
A good explanation of the mechanism can be found [http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter_10%3A_Phosphoryl_transfer_reactions/Section_10.3%3A_Hydrolysis_of__phosphates here].
Alkaline phosphatases, respectively their serum levels, are also related to several diseases e.g. metabolic myopathies and Paget Disease. [4]
Sequence and Features
- 10COMPATIBLE WITH RFC[10]
- 12COMPATIBLE WITH RFC[12]
- 21COMPATIBLE WITH RFC[21]
- 23COMPATIBLE WITH RFC[23]
- 25INCOMPATIBLE WITH RFC[25]Illegal NgoMIV site found at 340
Illegal NgoMIV site found at 787 - 1000COMPATIBLE WITH RFC[1000]
Characterization
[http://2013.igem.org/Team:ETH_Zurich ETH Zurich 2013] used PhoA in their project as reporter enzyme. To make predictions about their system, the model obviously needed parameters, so they decided to conduct fluorometric assays in order to obtain Km values.To this end bacterial cells were grown until in exponential growth phase. Upon reaching this, gene expression was induced by AHL (see [http://http://2013.igem.org/Team:ETH_Zurich/Infoproc their system]). After another 4-5h of growth, cells were harvested and lysed, the cell free extract used for the fluorometric assay. The properly diluted CFX was measured on a 96 well plate in triplicates per substrate concentration. A plate reader took measurements at λEx. 365nm and ΛEm. 445nm. The obtained data was evaluated and finally fitted to Michaelis-Menten-Kinetics with SigmaPlot™. See the resulting graph below.
References
- Molecular Cell Biology, Fifth Edition, W.H. Freeman & Co., 2004.
- [http://www.nlm.nih.gov/medlineplus/ency/article/003470.htm Medline Plus]
- [http://chemwiki.ucdavis.edu/Organic_Chemistry/Organic_Chemistry_With_a_Biological_Emphasis/Chapter_10%3A_Phosphoryl_transfer_reactions/Section_10.3%3A_Hydrolysis_of__phosphates Section 10.3: Hydrolysis of phosphates]
- Adams & Victor's Principles Of Neurology, 7th edition, McGraw-Hill Professional, 2000.
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