A (short) History of PCR

Kary Mullis conceived the idea for the polymerase chain reaction [1] in the spring of 1983 while an employee of Cetus Corporation, a biotechnology firm located near Berkeley, California. Mullis and his assistant Fred Faloona tried to get it to work later in the year, and were soon joined by other Cetus scientists who saw the great potential of this method. In this later group were people in Henry Erlich's lab, who had been working on methods to identify mutations in human genomic DNA as part of a DNA diagnostics group at Cetus. Description of PCR was terse in their first publication, a 1985 article in Science [2], on detection of the mutation causing sickle cell anemia in whole genomic DNA. The details of the PCR method and its uses were covered more fully in articles published in the next two years [3,4]. A general narrative of the invention of PCR, the internal politics of Cetus Corporation, and the philosophy and anthropology of scientific invention can be found in the book by Rabinow [5].

The DNA polymerase originally used for the PCR was extracted from the bacterium E. coli. However, after each cycle of DNA synthesis, the reaction must be heated to denature the double stranded DNA product. Unfortunately, heating also irreversibly inactivated this polymerase, so new enzyme had to be added at the start of each cycle. The bacterium T. aquaticus lives in hot springs, and produces a DNA polymerase which is not irreversibility inactivated at high temperature. David Gelfand and his associates at Cetus, purified [6], and subsequently cloned this polymerase [7], allowing a complete PCR amplification to be done with out opening the reaction tube. However, the thermostable enzyme was found to be much more than just a convenience. The DNA synthesis step could now be done at a higher temperature than was possible with the E. coli enzyme, and it was discovered that the template DNA strand was now copied with high fidelity, eliminating the nonspecific products that had plagued earlier attempts at amplification.

In 1993 Kary Mullis was awarded the Nobel Prize for the discovery of PCR.

1. Mullis, K. (1990). The unusual origin of the polymerase chain reaction. Scientific American April 56-65

2. Saiki, R., Scharf, S., Faloona, F., Mullis, K., Horn, G., and Erlich, H. (1985). Enzymatic amplification of beta-globin genomic sequences and restriction site analysis for diagnosis of sickle cell anemia. Science 230: 1350-54

3. Mullis, K., Faloona, F., Scharf, S., Saiki, R., Horn, G. and Erlich, H. (1986). Specific enzymatic amplification of DNA in vitro: the polymerase chain reaction. Cold Spring Harbor Symposium in Quantitative Biology 51: 263-73

4. Mullis, K. and Faloona, F. (1987). Specific synthesis of DNA in vitro via a polymerase-catalyzed chain reaction. Methods Enzymol 155: 335-350

5. Rabinow, P. (1996). Making PCR: A story of biotechnology. University of Chicago Press

6. Saiki, R., Gelfand, D., Stoffel, S., Scharf, S., Higuchi, R., Horn, G., Mullis, K. and Erlich, H. (1988). Primer-directed enzymatic amplification of DNA with a thermostable DNA polymerase. Science 239:487-91

7. Lawyer, F., Stoffer, S, Saiki, R., Chang, S., Landre, P., Abramson, R. and Gelfand, D. (1993). High-level expression, purification, and enzymatic characterization of full-length Thermus aquaticus DNA polymerase and a truncated form deficient in 5' to 3' exonuclease activity. PCR Methods and Applications 2: 275-87