EDTA: Difference between revisions
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EDTA | EDTA stands for ethylenediaminetetraacetic acid | ||
* | ==Purpose== | ||
*EDTA is a synthetic amino acid and chelating agent for divalent metals. | |||
* | *Most enzymes that synthesize or modify nucleic acids (e.g. polymerases, ligases, kinases, nucleases) are Mg<sup>2+</sup>-dependent. The addition of EDTA is a convenient way to stop these reactions. | ||
*EDTA is a component of many buffers used to store DNA, such as [[TE buffer]], where the EDTA removes the metal cofactors (typically Mg<sup>++</sup> required for activity of DNAses and other DNA damaging enzymes. | |||
* | ==Procurement== | ||
*Usually sold as the disodium salt (CAS 6381-92-6) (Sigma E1644). | |||
* | ==Use== | ||
*Molecular Weight, disodium salt dihydrate: 372.24 | |||
*EDTA is essentially insoluble in water, and will only dissolve when neutralized with sodium hydroxide to a pH = 8.0 | *EDTA is essentially insoluble in water, and will only dissolve when neutralized with sodium hydroxide to a pH = 8.0 | ||
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*Making the standard solution from disodium EDTA (the typical form sold) requires approximately 1 molar equivalent of NaOH | *Making the standard solution from disodium EDTA (the typical form sold) requires approximately 1 molar equivalent of NaOH | ||
* | *pK<sub>1</sub> = 1.99 | ||
*pK<sub>2</sub> = 2.67 | |||
*pK<sub>3</sub> = 6.16 | |||
*pK<sub>4</sub> = 10.26 | |||
*[http://www.vrp.com/art/963.asp Here's] | ==Interesting facts== | ||
*[http://www.vrp.com/art/963.asp Here's] an article that speaks of the wonders of EDTA and how it can help treat Aunt Edna's cardiovascular disease, enhance your enjoyment of the Friday night happy hour, and act as a "get out of jail free" card. | |||
*EDTA can prolong the life of your [http://www.deathstar.org/~flash/edta.html motorcycle battery]! | *EDTA can prolong the life of your [http://www.deathstar.org/~flash/edta.html motorcycle battery]! | ||
*EDTA helps you determine the hidden contents of your [http://homepages.ius.edu/DSPURLOC/c121/week13.htm hard water]. | *EDTA helps you determine the hidden contents of your [http://homepages.ius.edu/DSPURLOC/c121/week13.htm hard water]. | ||
==Safety== | |||
? | |||
==References== | |||
*[http://www.chm.bris.ac.uk/motm/edta/edtah.htm Here's] a great page about EDTA, including [http://www.cem.msu.edu/~cem333/EDTATable.html formation constant] (K<sub>f</sub>) values for metal-EDTA complexes. Note that many heavy metal ions (like Fe<sup>3+</sup>, Co<sup>2+</sup>, and Zn<sup>2+</sup>) are chelated much more strongly than Mg<sup>2+</sup>. A little bit of EDTA in your reaction will go a long way to keep these evildoers out of trouble and away from your precious biomolecules without interfering with your Mg<sup>2+</sup>-dependent reactions. | |||
[[Category:Material]] [[Category:Chemical]] | [[Category:Material]] [[Category:Chemical]] |
Revision as of 07:54, 11 March 2008
EDTA stands for ethylenediaminetetraacetic acid
Purpose
- EDTA is a synthetic amino acid and chelating agent for divalent metals.
- Most enzymes that synthesize or modify nucleic acids (e.g. polymerases, ligases, kinases, nucleases) are Mg2+-dependent. The addition of EDTA is a convenient way to stop these reactions.
- EDTA is a component of many buffers used to store DNA, such as TE buffer, where the EDTA removes the metal cofactors (typically Mg++ required for activity of DNAses and other DNA damaging enzymes.
Procurement
- Usually sold as the disodium salt (CAS 6381-92-6) (Sigma E1644).
Use
- Molecular Weight, disodium salt dihydrate: 372.24
- EDTA is essentially insoluble in water, and will only dissolve when neutralized with sodium hydroxide to a pH = 8.0
- Standard stock solutions are 0.5M at pH 8.0. A 1M solution cannot be made. Autoclave.
- Making the standard solution from disodium EDTA (the typical form sold) requires approximately 1 molar equivalent of NaOH
- pK1 = 1.99
- pK2 = 2.67
- pK3 = 6.16
- pK4 = 10.26
Interesting facts
- Here's an article that speaks of the wonders of EDTA and how it can help treat Aunt Edna's cardiovascular disease, enhance your enjoyment of the Friday night happy hour, and act as a "get out of jail free" card.
- EDTA can prolong the life of your motorcycle battery!
- EDTA helps you determine the hidden contents of your hard water.
Safety
?
References
- Here's a great page about EDTA, including formation constant (Kf) values for metal-EDTA complexes. Note that many heavy metal ions (like Fe3+, Co2+, and Zn2+) are chelated much more strongly than Mg2+. A little bit of EDTA in your reaction will go a long way to keep these evildoers out of trouble and away from your precious biomolecules without interfering with your Mg2+-dependent reactions.