High primer concentration improves PCR amplification from random pools. Nucl. Acids Res

The success of PCR is partly based on its exponential amplifica-tion characteristics. Nevertheless, in practice, the achievable yields are limited. Figure 1A and B shows the quantification of a typical reaction with varying but defined amounts of starting template. Every five cycles an aliquot of the reaction was removed and afterwards the amount of accumulated product quantitated. Although, initially, the amplification rates of all reactions reached the theoretical limit of 32-fold amplification during five cycles (indicated by a dashed line), a sharp decline in amplification rates was observed at later cycles. Interestingly this decline, which occurred in all reactions, did not depend on the total number of cycles in each reaction, but rather seemed to be coupled to the amount of accumulated product. In order to learn more about the basis of this phenomenon, I investigated the effect of primer concentration on PCR. For standard applications