Anfinsen, Christian

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Anfinsen, Christian

AMERICAN CHEMIST
1916–1995

Christian Boehmer Anfinsen was born in Monessen, Pennsylvania, on March 26, 1916. He earned a B.A. from Swarthmore College in 1937 and an M.S. from the University of Pennsylvania in 1939. In 1943 he received a Ph.D. in biochemistry from Harvard Medical School. He remained at Harvard for seven more years as an instructor and assistant professor of biological chemistry. In 1950 Anfinsen assumed the position of director of the Laboratory of Cellular Physiology and Metabolism at the National Heart Institute of the National Institutes of Health (NIH). This move led to a period of thirty years when he split his time between Harvard and the NIH until his retirement in 1981.

Anfinsen began his work on the relationship between protein structure and enzyme function in the mid-1950s in collaboration with F. H. White and Michael Sela at the Weizmann Institute in Rehovot, Israel. This research on the enzyme ribonuclease led him to propose that the structure of the amino acids in sequence along the protein chain contains the information determining the tertiary structure of the enzyme. Anfinsen demonstrated that the denaturation of the enzyme was reversible. After the cleavage of disulfide bonds and disruption of tertiary structure, some proteins spontaneously refold to native forms and their function returns. Anfinsen's advanced explanations of this observation became widely accepted.

The pursuit of the tertiary protein structural problem led Anfinsen to the discovery of a microsomal enzyme that catalyzes sulfhydryl-disulfide interchange and accelerates the refolding of denatured proteins which contain disulfide bonds in vitro . The kinetics of this folding accounts for the rate of folding of newly synthesized proteins in vivo . It was shown, however, that the renaturation required very dilute solutions in many cases to avoid aggregation of the protein in place of proper folding.

The importance of Anfinsen's work and that of his followers is the impact it has had on understanding certain diseases that involve the folding of enzymes. Recent discoveries indicate that Alzheimer's disease, cystic fibrosis, mad cow disease, genetic emphysema, and some cancers are all based on some aspect of protein folding gone awry. These folding problems also cause difficulties with the proper naturation of synthetic proteins under development for use as pharmaceuticals. Although Anfinsen could not have known the importance of his discoveries in the 1960s, he was somewhat concerned that the breaking of the genetic code and discovery of the α -helix structure of DNA overshadowed the work on protein and enzyme structure and function. He was awarded the Nobel Prize in chemistry (along with American chemists Stanford Moore and William Howard Stein) in 1972 for his pioneering work on the structure of enzymes and the relationship between the amino acid sequence and enzyme function. Anfinsen died in 1995 at the age of seventy-nine.

Lawrence H. Brannigan