Gibbs Medal
Khorana honored for genetic code work
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34th EXPOSITION OF CHEMICAL INDUSTRIES MANAGEMENT: INTERNATIONAL EXPOSITION CO., 200 PARK AVE., NEW YORK, N.Y. 10017 16
C&EN Nov. 5, 1973
On May 10, Dr. Har Gobind Khorana, an organic chemist at Massachusetts Institute of Technology, will receive one of the nation's most prestigious awards in chemistry—the Willard Gibbs Medal of the American Chemi cal Society's Chicago Section. Dr. Khorana will be honored for his out standing research on the synthesis of polynucleotides and on the nature of the genetic code. Since 1960, he has received a dozen awards from scientific organizations in several countries, including the U.S., Canada, India, and West Germany. He is best known, however, for winning the 1968 Nobel Prize in Physiology or Medicine, along with two other U.S. pioneers in the study of the genetic code, Dr. Marshall W. Nirenberg and Dr. Robert W. Holley. The following year, he received the ACS Award for Creative Work in Synthetic Organic Chemistry. Among Dr. Khorana's important early scientific achievements was his research on the reactions of carbodiimides. He used these reagents to syn thesize many compounds, including coenzyme A and other nucleotide coen zymes, in conjunction with Dr. John G. Moffatt. These studies, which were done while he was head of the organic chemistry section (1952-60) of the British Columbia Research Council at the University of British Columbia in Vancouver, have been highly useful to other scientists in carrying out chemi cal syntheses in a variety of fields. Later, while at the University of Wisconsin (1960-70), where he was codirector of the Institute of Enzyme Research, Dr. Khorana did his historic work on the chemical synthesis of com plex polynucleotides containing known sequences of nucleotide bases. His ef forts helped to clarify major aspects of the genetic code. He and others showed that the ge netic code of deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) for each amino acid consists of three-letter "words," each word being a specific se quence of three nucleotides that may call up from the surrounding medium any one of 20 amino acids to form pro tein chains. In the course of this re search, Dr. Khorana synthesized a va riety of high-molecular-weight DNAlike polymers having completely de fined sequences. Also, he synthesized all of the 64 possible ribotrinucleotides. As another important contribution, he and his group demonstrated that the three-letter code words do not overlap —that is, no code word shares any of its letters with an adjoining word. In recent years, Dr. Khorana and his associates have devoted special atten tion to the total synthesis of genes. In 1970, shortly before leaving the Univer
sity of Wisconsin, he announced the synthesis of a yeast gene that produces the transfer RNA specific for the amino acid alanine (C&EN, June 8, 1970, page 9). A product of five years of research, this synthetic gene, consist ing of a double-stranded DNA mole cule, contains 77 nucleotide base pairs. Recently, Dr. Khorana and cowork ers reported success in synthesizing a more complex gene (C&EN, Sept. 17, page 18). This one, found in the bacte rium Escherichia coli, contains 126 nu cleotide base pairs. This gene codes for the production of the transfer RNA specific for the amino acid tyrosine. Currently, Dr. Khorana and cowork ers also are studying the regions of genes that control the starting or stop ping of transcription by a gene, as a given cell may require. "We want to understand the chemical nature of these two types of regions—the initia tor and terminator regions—that regu late RNA formation from DNA," he says. "Eventually, we hope to synthe size these DNA segments." Looking still farther into the future, Dr. Khorana says that he is interested in doing research on the chemical na ture of cell membranes. Even when this work is under way, he says, he still expects to continue his studies of DNA and RNA—work that has been re ported in more than 300 papers that he has authored or coauthored. Today at MIT, Dr. Khorana is Al fred P. Sloan Professor of Biology and Chemistry. As was the case when he was at the University of Wisconsin, he teaches no courses at MIT. Rather, he pursues his research full-time, with the aid of a dozen or so postdoctoral asso ciates, most of whom are chemists, biochemists, and molecular biologists. Born in Raipur, India, in 1922, he re ceived his B.S. (1943) and M.S. (1945) from Punjab University and went on to obtain his Ph.D. (1948) from the Uni versity of Liverpool. Married and the father of three chil dren, he says he has almost no nonfamily interests apart from his work. One of his few outside enthusiasms is hiking. He spends hours hiking through wooded areas, often while thinking deeply about his research and occa sionally stopping to record his thoughts on index cards.
