Biomics

Despite the high specificity and sensitivity of PCR, it is not uncommon for experimenters to encounter the inability to obtain results in satisfactory volumes and quality due to either poor production of target amplicons or even complete absence of such due to inhibition of the amplification process, or on the contrary, multiple amplicons instead of single expected one. The reasons for such failures are both various substances extracted together with nucleic acids from the analyzed samples, which are inhibitors of DNA polymerase, and the nucleotide sequences of the target themselves, which form strong secondary structures that DNA polymerase is unable to overcome or does it very inefficiently. However, to enhance the work of DNA polymerase and increase the specificity of primer annealing, it is possible to use various chemicals or biological preparations additionally added to the reaction mixture and called enhancers. At the same time, different types or classes of PCR enhancers affect different components of the reaction mixture, leading to an improvement in the enzymatic activity of the enzyme, including adding modified nucleotides in the growing chain, depriving amplicons of a strong secondary structure, as well as ensuring the annealing of primers in strictly targeted locations, thereby eliminating nonspecific amplification. This review briefly examines the most commonly used enhancers, divided into groups by chemical composition and biological origin. Moreover, it should be noted that different enhancers in different concentrations in various experiments may or may not show their activity, which depends on the nucleotide sequences of the target and contaminants. In fact, enhancers and thermal cycling modes need to be selected individually for each target.

PCR, enhancers, DNA polymerase, primer, DMSO, formamide, betaine, specificity

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