Bromophenol blue: Difference between revisions
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[[Image: | {{unreferenced|date=February 2007}} | ||
[[Image:Bromophenol_blue.gif|frame|right|Bromophenol Blue]] | |||
{{pH_indicator_template|indicator_name=Bromophenol blue|low_pH=3.0|high_pH=4.6|low_pH_color=yellow|high_pH_color=purple}} | |||
'''Bromophenol blue''', ''Tetrabromophenolsulfonephthalein'', is an acid-base [[pH indicator|indicator]] whose useful range as an indicator lies between [[pH]] 3.0 and 4.6. It changes from yellow at pH 3.0 to purple at pH 4.6; this reaction is reversible. | |||
Bromophenol blue is also used as a color marker to monitor the process of [[agarose gel electrophoresis]] and [[SDS PAGE|polyacrylamide gel electrophoresis]]. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction as [[DNA]] or [[protein]] in a gel; the rate at which it migrates varies according to gel density and [[buffer solution|buffer]] composition, but in a typical 1% [[agarose]] gel in [[TAE buffer]] or [[TBE buffer]], bromophenol blue migrates at the same rate as a DNA fragment of approximately 500 [[base pair]]s. [[Xylene cyanol]] and [[Orange G]] may also be used for this purpose. | |||
The molecular weight of bromophenol blue is around 670 [[dalton (unit)|Dalton]]s or grams per mole. | |||
The bromophenol blue is also used as a dye. At neutral pH, the dye absorbs red light most strongly and transmits blue light. Solutions of the dye therefore are blue. At low pH, the dye absorbs ultraviolet and blue light most strongly and appears yellow in solution. | |||
In solution at pH 3.6 (in the middle of the transition range of this pH indicator) obtained by dissolution in water without any pH adjustment, bormophenol blue has a characteristic green red colour. This phenomenon is called [[dichromatism|dicromatic colour]]<ref>Kreft S and Kreft M (2007) Physicochemical and physiological basis of dichromatic colour, Naturwissenschaften (in press) [http://www.springerlink.com/content/h5630lr536pj1333/fulltext.pdf On-line PDF]</ref>.. | |||
Bromophenol blue is commonly used in entry-level lab courses to stain proteins in wet-mount slides. | |||
== | == References== | ||
<references /></div> | |||
[[Category: | [[Category:pH indicators]] | ||
[[Category:Triarylmethane dyes]] | |||
[[de:Bromphenolblau]] | |||
[[fr:Bleu de bromophénol]] | |||
[[it:Blu di bromofenolo]] | |||
[[ja:ブロモフェノールブルー]] | |||
[[pl:Błękit bromofenolowy]] | |||
[[pt:Azul de Bromofenol]] | |||
[[vi:Bromophenol xanh]] | |||
{{organic-compound-stub}} | |||
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Revision as of 21:03, 9 July 2009
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Template:PH indicator template Bromophenol blue, Tetrabromophenolsulfonephthalein, is an acid-base indicator whose useful range as an indicator lies between pH 3.0 and 4.6. It changes from yellow at pH 3.0 to purple at pH 4.6; this reaction is reversible.
Bromophenol blue is also used as a color marker to monitor the process of agarose gel electrophoresis and polyacrylamide gel electrophoresis. Since bromophenol blue carries a slight negative charge at moderate pH, it will migrate in the same direction as DNA or protein in a gel; the rate at which it migrates varies according to gel density and buffer composition, but in a typical 1% agarose gel in TAE buffer or TBE buffer, bromophenol blue migrates at the same rate as a DNA fragment of approximately 500 base pairs. Xylene cyanol and Orange G may also be used for this purpose.
The molecular weight of bromophenol blue is around 670 Daltons or grams per mole.
The bromophenol blue is also used as a dye. At neutral pH, the dye absorbs red light most strongly and transmits blue light. Solutions of the dye therefore are blue. At low pH, the dye absorbs ultraviolet and blue light most strongly and appears yellow in solution. In solution at pH 3.6 (in the middle of the transition range of this pH indicator) obtained by dissolution in water without any pH adjustment, bormophenol blue has a characteristic green red colour. This phenomenon is called dicromatic colour[1]..
Bromophenol blue is commonly used in entry-level lab courses to stain proteins in wet-mount slides.
References
- ↑ Kreft S and Kreft M (2007) Physicochemical and physiological basis of dichromatic colour, Naturwissenschaften (in press) On-line PDF