Long-Range Polymerase Chain Reaction.

Polymerase chain reaction (PCR) is a laboratory technique used to amplify a targeted region of DNA, demarcated by a set of oligonucleotide primers. Long-range PCR is a form of PCR optimized to facilitate the amplification of large fragments. Using the adapted long-range PCR protocol described in this chapter, we were able to generate PCR products of 6.6, 7.2, 13, and 20 kb from human genomic DNA samples. For some of the long PCRs, successful amplification was not possible without the use of PCR enhancers. Thus, we also evaluated the impact of some enhancers on long-range PCR and included the findings as part of this updated chapter.

PCR enhancers: Types, mechanisms, and applications in long-range PCR.

Polymerase chain reaction is an important tool in molecular biology. Although the principles of the technique are relatively simple, amplifying complex or long DNA segments can be challenging. A variety of PCR additives are used to improve the performance and yield of difficult PCRs. Each PCR additive has unique properties and enhances PCR through a different mode of action. They are used to either improve PCR sensitivity, efficiency, and specificity, or mitigate the effects of PCR inhibitors. In this review, we categorise known PCR additives into four main groups. The first three groups comprise PCR additives with well-defined mechanisms, namely those that facilitate the amplification of GC-rich sequences, counteract the detrimental effects of PCR inhibitors, or alter PCR kinetics (nanomaterials). The fourth group is a loose mix of additives with unclear mechanisms of action. Then, we discuss how these additives may be used to tackle specific PCR-related challenges, particularly those associated with long-range PCR. We conclude the review with added insights into the use of PCR additives in enhancing the synthesis of complex and long DNA fragments.