TTH DNA POLYMERASE-MEDIATED AMPLIFICATION OF DNA FRAGMENTS USING PRIMERS WITH MISMATCHES IN THE 3'-REGION

The ability of three thermostable enzymes, Tth, Taq, and Klentaq DNA p olymerases, to amplify DNA with primers containing mismatches in the 3 '-terminal region was studied. it is shown that Tth polymerase, in con trast to the Tag and Klentaq enzymes, synthesizes equally well DNA wit h primers perfectly complementary to the template and with those conta ining mismatches next the 3'-end. The use of Tth DNA polymerase in the polymerase chain reaction was shown to result, in some cases, in a gr eat number of additional, nonspecific DNA fragments as compared with T aq DNA polymerase. This may be due to the ability of Tth polymerase fo r DNA primer extension even if the S'-terminal region of the primer co ntains nucleotides noncomplementary to the template. Tth DNA polymeras e and a Klentaq/Tth mixture (100 : 1) can be efficiently used in the a mplification of DNA with degenerated primers and primers forming nonpe rfect duplexes with the template.