Why the DNA loading Dye is made up of Bromophenol blue and Xylene cynaol? Is not there any other chemical which can be used in place of Bromophenol blue and Xylene cyanol?
These are dyes to predict your desired DNA migration.
Bromophenol blue migrates almost equal to the migration of ~300bp, whereas Xylene Cyanol migrates arount 3Kb. Similarly Orange G migrates around 50bp and cresol red 1.5Kb.
Depending on your desired DNA length you can choose your dye fronts. commonly used dyes are BPB and XC-FF, since the range is wide..
Hi there,
They are both migrating both towards the anode like nucleic acids. So they are easily spotable on a gel and depending on the condition of gel and migration they exhibit the mobility of DNA fragments of a certain size then you are able without staining the gel to estimate how far the samples have migrated. See the following for more info:
http://cbs.umn.edu/springer-lab/protocols/gels
Just want to add to Dominique's explanation ,
As Dominique's said, uses of the two dyes are to track the DNA molecule in the gel during the course of gel electrophoresis. Generally, on a normal 0.8% or 1.0% Agarose gel, the bromophenol blue migration rate is equivalent to 350 - 400bp while Xylene cyanol is equivalent 3 - 4Kbp. So during electrophoresis, Xylene makes the lower dye front while bromophenol blue makes the upper dye front. These two dye front help the user to monitor the rate of migration and to prevent the over-running of gel.
In addition, sample loading to the gel is much easier with coloured solutions.
These are dyes to predict your desired DNA migration.
Bromophenol blue migrates almost equal to the migration of ~300bp, whereas Xylene Cyanol migrates arount 3Kb. Similarly Orange G migrates around 50bp and cresol red 1.5Kb.
Depending on your desired DNA length you can choose your dye fronts. commonly used dyes are BPB and XC-FF, since the range is wide..
Hi Aqleem,
There are other dyes available as well. I wrote a small blurb about it here:
https://insitutech.wordpress.com/2018/01/30/loading-dyes-for-electrophoresis-gels/
Best
Simone
Hi,Both dyes are for tracking the movement of the nucleic acid during agarose gel electrophoresis so that it does not run off into the buffer and you lose it.
Hi Simone may I ask if methylene blue is a suitable dye too? Thanks!@Simone Schindler
Kong Kahin just because it's blue colour doesn't mean it has the same properties :)
Now seriously,no, methylene blue cannot be used because it has positive charge and thus migrates in opposite direction than DNA or (SDS-)proteins.
https://en.wikipedia.org/wiki/Methylene_blue
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