InstrumentationMolecular Biology

Extraction Buffer

Extraction Buffer

Extraction buffers are chemical solution used for extraction of molecules such as DNA, RNA, proteins etc. which maintains/resist pH change during the process. As the molecules are of several charge and ambient pH, it may interfere with reaction mixture and may give wrong/faulty results which are stabilized or minimized by buffer.


Cell disruption process is carried out in presence of buffer which maintains the integrity of biomolecules within the cell so it is called Extraction Buffer. They are also called as recovery buffer as these are used during recovering the desired nucleic material, proteins etc. by disrupting the cells.


The composition of buffer used for extraction is an essential part for disrupting cell to release proteins from it. It consists of buffer salts and ionic salts to maintain ionic strength and osmolarity of lysates. Detergents present breaks up or disrupt the membranes. Different buffers have different pH range so, it should be chosen based upon whether the lysate will be stable in particular pH of buffer solutions.

Common components of recovery buffer includes antioxidants, EDTA, enzyme substrate and cofactors, enzyme inhibitors, sodium azide, Polyvinylpyrrolidone etc.


Extraction Buffer


Nature of cell or extract determines type of extraction buffer to be used during cell disruption process. Usually, extraction buffer of an ionic strength (0.1-0.2M) and pH (7.0-8.0) is used for most of extraction process as these conditions are considered to be compactible to environment inside the cell. Tris or Phosphate buffers are most commonly used extraction buffer. NP-40 lysis buffer, RIPA (Radio Immuno Precipitation Assay) lysis buffer etc. are some recovery solutions.


These buffers are used for isolation of proteins, enzymes, nucleic materials etc. form both plant and animal cells. It can be used for number of functions such as:

  1. Extraction of DNA, RNA, proteins etc.
  2. Preservation of DNA, RNA, proteins sample.
  3. Act as co-factor which boost reactions due to presence of Mg++ and EDTA.
  4. Prevention of disruption of DNA, RNA.

 Importance of extraction buffer

  1. To protect molecular components from getting destroyed/damaged.
  2. To protect from nuclease enzymes (DNAse, RNAse) which may interfere charges of DNA and RNA molecules.
  3. To maintain stable pH and environment during separation and extraction.
  4. To remove contaminants and obtain desired product. E.g. proteins are dissolved in aqueous phase and do not precipitate in alcohol along with DNA.

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