How restriction enzymes became the workhorses of molecular biology

Abstract

Restriction enzymes have proved to be invaluable for the physical mapping of DNA. They offer unparalleled opportunities for diagnosing DNA sequence content and are used in fields as disparate as criminal forensics and basic research. In fact, without restriction enzymes, the biotechnology industry would certainly not have flourished as it has. The first experiments demonstrating the utility of restriction enzymes were carried out by Danna and Nathans and reported in 1971. This pioneering study set the stage for the modern practice of molecular biology in which restriction enzymes are ubiquitous tools, although they are often taken for granted.

Fig. 1.

Radioautogram of ¹⁴C-labeled SV40 DNA cleaved with endonuclease R showing the 11 distinct fragments (figure 3 from ref. ; courtesy of the Nathans family and Kathleen Danna).

Fig. 2.

Sucrose gradient analysis of ³H-labeled SV40 DNA cleaved with endonuclease R (figure 1 from ref. ; courtesy of the Nathans family and Kathleen Danna).

Fig. 3.

Electrophoretic analysis of ³²P-labeled SV40 DNA cleaved with endonuclease R. After electrophoresis, individual slices from the gel were quantitated by scintillation counting (figure 2 from ref. ; courtesy of the Nathans family and Kathleen Danna).

Fig. 4.

Dan Nathans (left) and Hamilton Smith (right) in the laboratory at Johns Hopkins University (Copyright 1978, Susie Fitzhugh).