| abstract |
The invention relates to compositions, methods, and kits for hot start polynucleotide synthesis, including extension of primed polynucleotide templates and polymerase chain reaction (PCR). Hot start is provided by a thermally inactivated blocking polymerase protein that binds primed polynucleotide templates and prevents their access to a thermostable nucleic acid polymerase. High temperatures employed in the synthesis reaction cause the blocking polymerase to denature, thereby permitting the action of a thermostable processive polymerase. Compositions of the invention include a specific blocking polymerase protein which is a mutant of the Klenow fragment of E. coli DNA polymerase. The mutant is essentially devoid of polymerase activity, processivity, and 3′ to 5′ exonuclease activity. Use of the thermally inactivated blocking polymerase together with a thermostable polymerase reduces non-specific priming and accumulation of unwanted amplification products, increasing the specificity and sensitivity of the synthesis reaction. |