John C. Kendrew

views updated

John C. Kendrew

John C. Kendrew (born 1917) was awarded the Nobel Prize in chemistry (with Max Perutz) in 1962 for his work in determining protein structures.

John Cowdery Kendrew was born in Oxford, England, on March 24, 1917, the son of Wilfred George and Evelyn May Graham (Sandberg) Kendrew. His father was a climatologist at the university; thus young Kendrew was raised in a highly enriched, scientific atmosphere. He trained as a physical chemist upon entering Cambridge, taking his B.A. from Trinity College in the spring of 1939. After graduation he considered switching to biology for further study, but without clear direction, and with the outbreak of World War II he joined the Air Ministry and worked on the application of airborne radar to the war effort and as a civilian scientist for the Royal Air Force. Kendrew worked for the RAF until 1945, first in England, then in the Middle East, and finally in Southeast Asia.

Early Interest in Structural Chemistry

It was in the Far East that he first became acquainted with J. D. Bernal, the great structural chemist and later scientific adviser to Lord Mountbatten. Ironically, Bernal had been working at Cambridge throughout the 1930s utilizing x-ray diffraction to determine the structure of crystals. This is accomplished by directing a beam of x-rays upon a crystal and capturing the diffraction pattern established upon a photographic plate. Bernal was at that time excited about the possibility of determining the structure of proteins through the use of x-rays, and he convinced Kendrew that the field was ready for cultivation. Kendrew's mind was thus at work upon structures when, on a military trip to California, he met Linus Pauling and learned of his interest in protein and amino acid structures. The combined influence of Bernal and Pauling persuaded him to switch from chemistry to biology, and with the war's end he returned to Cambridge to pursue his doctorate.

Work with Myoglobin

Max Perutz, a former student of Bernal's, was already working on the structure of hemoglobin at Cambridge's Cavendish Laboratory when Kendrew joined him in 1946. From Perutz he learned the elements of crystallography, and he began his doctoral research on the protein myoglobin. Kendrew chose this protein because of its close relation to hemoglobin, but also because it was one-quarter the size (2,500 atoms to hemoglobin's 10,000). While actively engaged in this research, and though he had not yet finished his doctoral requirements, Kendrew rose rapidly in the post-war academic hierarchy. In 1947 he was named department chairman of the Medical Research Council Laboratory for Molecular Biology, also in the Cavendish Laboratory under Sir Lawrence Bragg but later in its own building, a post he held at Cambridge until 1975—a period concurrent with his being a fellow of Peterhouse. In 1949 he finished his Ph.D., but he continued to work on the structure of myoglobin as the determination of its crystalline arrangement was still unsolved.

In 1953 Perutz discovered a new technique that was to unravel the mystery of the protein. He showed that attaching a single atom, such as gold or mercury, to a hemoglobin molecule slightly altered the diffraction pattern. By a comparison of before and after photographs it was possible to determine the heavy atoms' positions in the hemoglobin crystal. This method, known as isomorphic replacement, could potentially solve the entire puzzle of hemoglobin structure. Kendrew applied it to the simpler molecule myoglobin, succeeding by 1957—after thousands of photographs and repeated measurements—in unraveling the first protein structure. This first picture was rather blurred, but by 1959, after many more photographs and measurements, Kendrew and his associates achieved a very high resolution, such that most of the individual atoms were now "visible." Eventually, nearly every atom's location in the molecule was determined, but at the time the polypeptide chain was shown to coil about in a spiral manner already described theoretically by Pauling in 1951 and called the alpha-helix.

For their work Perutz and Kendrew were awarded the 1962 Nobel Prize in chemistry. Kendrew received other recognition for his work in what is now commonly known as molecular biology—a 1960 fellow of the Royal Society; decorated knight bachelor and commander, Order of the British Empire; and foreign associate, National Academy of Sciences (United States). After 1959 he was editor-in-chief of the Journal for Molecular Biology, and in 1970 he left Cambridge for the post of director-general of the European Molecular Biology Laboratory in Heidelberg, Germany, which he held until 1982.