Composition and Ingredients of DNA Loading Dye

  • The composition and concentration of DNA loading dye can vary a lot. However, all DNA loading dyes contain two essential components:
    • High-density reagent
    • Tracking dye
  • The simplest DNA loading dye contains at least one tracking dye and one high-density reagent. The most common and widely used DNA loading dye contains two tracking dyes and a high-density reagent.
  • In addition to tracking dyes and high-density reagent, DNA loading dye can be supplemented with EDTA, SDS or Tris.
IngredientsConcentration(in 6x loading dye)Remarks
High-density reagents: Usually a DNA loading dye contains one high-density reagent. Any of the following reagents can be added to the loading dye.
Glycerol60% (v/v)Interact with borate of TBE electrophoresis buffer. Do not use it with the TBE buffer.
Sucrose40% (w/v)Prone to mold-like growth
Ficoll 40015% (w/v)Can be stored at room temperature, quite stable
Tracking dyes: One or more tracking dyes can be added.
Bromophenol blueConc range: 0.03 – 0.5 % (w/v)Standard conc: 0.25% (w/v)Migration corresponds to the migration of 4000 – 5000 bp long DNA fragments in 1% agarose gel
Xylene cyanolConc range: 0.03 – 0.5 % (w/v)Standard conc: 0.25% (w/v)Migration corresponds to the migration of 4000 – 5000 bp long DNA fragments in 1% agarose gel
Orange GConc range: 0.15 – 0.5 % (w/v)Standard conc: 0.4% (w/v)Migration corresponds to the migration of 40 – 45 bp long DNA fragments in 1% agarose gel
Optional/special purpose reagents
Tris.Cl (pH 7.6)10 mMMaintain the pH of loading dye 
EDTA60 – 100 mMProtect DNA from DNA modifying enzymes by sequestering divalent cations
SDS1%Removes tertiary structure of DNA and eliminate protein from DNA

REFERENCES

  • Sciarra & Elliott, 1960. A solubility study of the boric acid-glycerin complex. I. Solubility of boric acid in glycerin solution at 25 degrees. J Am Pharm Assoc Am Pharm Assoc. 49, 115-117. PMID-13854731; Full Text Links: wiley, readcube, booksc

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