Sidney Altman

Sidney Altman, born in 1939, Canadian-born American chemist, molecular biologist and Nobel laureate. Altman discovered that ribonucleic acid (RNA) can act as a catalyst (see Catalysis), or initiator, of cellular reaction. Previously, scientists had believed that only proteins could perform this important chemical function. Altman's work revolutionized the field of biochemistry by presenting a new theoretical explanation for the origin of life. For his discovery of the catalytic properties of RNA, Altman was awarded the 1989 Nobel Prize in chemistry, which he shared with American chemist Thomas Robert Cech.

Born in Montréal, Québec, Canada, Altman did his undergraduate work at the Massachusetts Institute of Technology (MIT). He received his Ph.D. degree from the University of Colorado in 1967. In 1971 he joined the faculty of Yale University as an assistant professor of biology, becoming a full professor in 1980. He served as chairman of the Department of Biology from 1983 to 1985 and as dean of Yale College from 1985 to 1989.

Deoxyribonucleic acid (DNA), one of the nucleic acids, stores genetic information within cells, while enzymes are protein molecules that cause cellular reactions. RNA is the go-between, translating genetic information to protein by means of small molecules called transfer RNA (tRNA). While studying the formation of tRNA in 1978, Altman discovered an enzyme called ribonuclease P (RNase P), composed of both RNA and a protein. He noted that RNase P caused the splicing of tRNA molecules and assumed that the protein portion of the enzyme had caused this reaction. He then noted that the protein component acting alone did not splice the transfer RNA molecule. After isolating the RNA component (called M1 RNA) and repeating the experiment, Altman demonstrated that the M1 RNA had acted alone to cause the reaction. Because this process violated an absolute of molecular biology (that only proteins function as catalysts), Altman's findings were initially greeted with skepticism and indifference. But Thomas Robert Cech, working independently of Altman, documented a cellular reaction in which RNA acted as a self-catalyst. Cech called this self-acting RNA a ribozyme.

These discoveries astounded the scientific community. It was now possible to suggest that RNA, not proteins, may have served as the regulator in primitive cells when life was first formed. Since DNA cannot form without a catalyst, and proteins cannot act as a catalyst without DNA, it now appears that RNA serves both functions. Altman and Cech had basically provided a new theory as to how life develops.