Cech , Thomas Robert

(1947–) American chemist

Chicago-born Cech was educated at the University of California, Berkeley, where he gained his PhD in 1975. He then joined the faculty of the University of Colorado, Boulder, where he became professor of chemistry in 1983.

In 1977 Philip Sharp discovered long stretches of non-coding DNA, later called ‘introns’. In 1982 Cech began to investigate how these supposedly redundant sequences could be removed from the RNA molecule after it had been copied from the DNA template. For such a complex process to happen so rapidly it must, it seemed, be catalyzed by an enzyme. Since the first enzyme to be synthesized (by James Sumner in 1926) had turned out to be a protein, and since all of the hundreds of other cellular enzymes had also turned out to be proteins, Cech confidently began to search for the protein enzyme responsible for snipping introns from RNA molecules.

He worked with ribosomal RNA (rRNA) of the protozoaTetrahymena thermophilia. He began with some unspliced rRNA and some protozoa nuclei mixed together in vitro. He assumed that the nuclear enzymes would catalyze the splicing. But, although the RNA introns were indeed neatly snipped away, none of the nuclear enzymes appeared to have been used. At first Cech assumed that the RNA itself harbored the protein enzyme responsible. To eliminate this possibility Cech synthesized his own pre-rRNA from a recombinant DNA template. The result was a viable but artificial rRNA, which, never having been in contact with a cell, could not possibly contain any cellular splicing enzymes. Despite this the introns were still removed.

RNA, Cech concluded in 1982, must be self-splicing. It acted like an enzyme in catalyzing a specific reaction, at a greatly accelerated rate, yet, unlike an enzyme, it operated upon itself. To mark the difference Cech proposed the name ‘ribozyme’.

Confirmation of Cech's researches soon came from the work of Sidney Altman on ribonuclease. For this work, Cech and Altman shared the 1989 Nobel Prize for chemistry.