Arber, Werner (1929– )

Swiss biochemist who was awarded a Nobel Prize for Physiology or Medicine in 1978 for his discovery of restriction enzymes (bacterial enzymes that can break a chain of DNA in two at a specific point). Restriction enzymes are used in genetic engineering.

Arber was born in Granichen, Switzerland, and studied at the Swiss Federal Institute of Technology. In 1949, he left for Geneva to work on bacteriophages (viruses that attack and grow in bacteria). By 1962, Arber had conducted a series of experiments to show the genetic basis of ‘host-induced’ variation (the phenomenon by which a bacteriophage adapts to the particular strain of bacteria that it grows in).

In Arber's theory, certain bacterial strains were postulated to contain restriction enzymes which were able to cleave unprotected (bacteriophage) DNA. Furthermore, these restriction enzymes must have the ability to recognize a specific sequence of nucleotides within a bacteriophage DNA molecule in order not to destroy the bacteria's own DNA. These enzymes would protect bacteria from infection since bacteriophage DNA would be broken before it could replicate and destroy a cell.

Arber went on to purify and characterize a sequence-specific restriction enzyme. Today such enzymes are routinely used by molecular biologists in genetic engineering to create pieces of DNA of a specified length.