A Programmable System to Perform the Polymerase Chain Reaction

An automated system is described that performs the cyclic temperature changes required for enzymatic amplification of specific DNA segments in vitro using the polymerase chain reaction (per). During per, oligonucleotide primer molecules are bound at low temperature to templates of heat-denatured DNA and extended on their 3′ end using a thermostable DNA polymerase. The DNA denaturation, primer annealing, and extension is repeated several times under program control to accumulate a large number of identical copies of the DNA sequence between the primers. A microcomputer system controls the flow of 96°C and 37°C water through a 24-well sample holder so that the temperature in the samples in the holder varies as required for DNA denaturation, primer annealing, and DNA polymerization. The microcomputer automatically performs multiple thermal cycles and is sufficiently flexible that the temperature profile can be varied from cycle to cycle.