The enhancement of PCR amplification by low molecular weight amides

Amplification of a DNA target by the polymerase chain reaction (PCR) often requires laborious optimization efforts. In this regard, the use of certain organic chemicals such as dimethyl sulfoxide, polyethylene glycol, betaine and formamide as cosolvents has been found to be very helpful. Unfortunate ly, very little is known about the precise structural features that make th ese additives effective and, accordingly, the number of such chemicals curr ently known to enhance PCR is limited. In order to address these issues, we decided to focus on formamide and undertook an extensive study of low mole cular weight amides as a class to see how changing the substituents in the amide structure influences its effect on PCR, We describe here the results of this study, which involved 11 different amides, and present observations that provide a cohesive picture of structure-activity relations in this gr oup of additives. We found several of these amides to be exceptionally effe ctive and introduce them as novel PCR enhancers.