ASBMB Nobel Prize Winners

1978 – Hamilton O. Smith



Hamilton Othanel Smith (1931 - present) was awarded one-third of the Nobel Prize for Physiology or Medicine in 1978 for his discovery of a class of restriction enzymes (used by the cell to splice two pieces of DNA) that recognize specific sequences of nucleotides in DNA and cleave it at particular points. While studying how the bacterium Haemophilus influenzae takes up DNA from the phage virus P22, Smith and his colleagues discovered the first of what came to be called type II restriction enzymes. These enzymes not only recognize a specific region in a DNA sequence but always cut the DNA at that very site. This predictable behavior made type II restriction enzymes valuable tools in the study of DNA structure and in recombinant DNA technology (in which artificial DNA is made by combining other DNA sequences together).