(1916–1995) American biochemist
Born in Monessen, Pennsylvania, Anfinsen was educated at Swarthmore College, the University of Pennsylvania, and Harvard, where he obtained his PhD in 1943. He taught at Harvard Medical School from 1943 to 1950, when he moved to the National Heart Institute at Bethesda, Maryland, where from 1952 to 1962 he served as head of the laboratory of cellular physiology. In 1963 Anfinsen joined the National Institute of Arthritis and Metabolic Diseases at Bethesda, where he was appointed head of the laboratory of chemical biology. In 1982 he became professor of biology at Johns Hopkins University.
By 1960 Stanford Moore and William Stein had fully determined the sequence of the 124 amino acids in ribonuclease, the first enzyme to be so analyzed. Anfinsen, however, was more concerned with the shape and structure of the enzyme and the forces that permit it always to adopt the same unique configuration. The molecule of ribonuclease – a globular protein – consists of one chain twisted into a ball and held together by four disulfide bridges. By chemical means, the sulfur bridges can be separated so that the enzyme becomes a simple polypeptide chain with no power to hydrolyze ribonucleic acid, i.e. it becomes denatured. Once the bridges are broken they can be reunited in any one of 105 different ways. Anfinsen found that the minimum of chemical intervention – merely putting the enzyme into a favorable environment – was sufficient to induce the ribonuclease to adopt the one configuration that restores enzymatic activity.
The important conclusion Anfinsen drew from this observation was that all the information for the assembly of the three-dimensional protein must be contained in the protein's sequence of amino acids – its primary structure. He went on to show similar behavior in other proteins. For this work Anfinsen shared the 1972 Nobel Prize for physiology or medicine with Moore and Stein.
Subjects: Science and Mathematics.