PCR inhibitors

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Inhibitor schematic.png

Many compounds also contained in the PCR template beside the target DNA can interfere with the polymerisation of nucleotides by the Taq or a related polymerase. This may result in false negative results, i.e. no PCR product even though the template is present.

Inhibitors from the purification process

  • alcohols like ethanol and 2-propanol (isopropanol) from DNA template precipitation (Qiagen test of sequencing inhibition by Welters et al. 1997)
  • organic solvents like phenol from phenol/chloroform purification (PMID 8136148)
  • salts like KCl, NaCl from precipitation
  • detergents like SDS,.. from membrane lysis (PMID 2223070)

Inhibitors from the source tissue

  • components of blood: heme, hemoglobin, lactoferrin, immunoglobin G (IgG)
  • liver, digestive tract, feces: bile salts, polysaccharides
  • connective tissue, skin: collagen, melanin
  • urine: urea

See Rådström et al. 2004 (PMID 14764939) for a review on how to avoid inhibition from tissue components.

Template inhibition

See also