Thomas R. Cech received the Dr H.P. Heineken Prize for Biochemistry and Biophysics 1988 for one of the most sensational discoveries in biochemistry in the last few years by showing that RNA can act as an enzyme.
Up till then the ‘dogma’, that all biological catalysts are proteins, had not been questioned. Cech and his co-workers demonstrated that the large ribosomal RNA precursor of Tetrahymena thermophilia has the capacity of self-splicing or self-processing. In the complete absence of a protein enzyme, an intervening sequence (IVS or intron) is removed and the remaining RNA pieces are ligated correctly. The only requirement for this reaction is the presence of guanosine (or a derivative thereof, like for instance GMP) and magnesium ions. Cech and his colleagues were able to clarify the mechanistic details of this reaction.
The finding that RNA can act as an enzyme (also called ribozyme) active in breaking and making internucleotide bonds in present-day biological systems, raises the question whether these properties may have played a role in the prebiotic replication and evolution of RNA molecules. Since the substrate oligonucleotides are aligned by a complementary sequence in the IVS RNA itself, the polymerization reaction fulfils one of the requirements of a primitive autocatalytic replication mechanism. RNA has the qualities which are required for a hypercycle mechanism.
About twenty years ago Francis Crick remarked: ‘RNA is a molecule which desperately tries to be a protein.’ Thomas Cech demonstrated that RNA indeed is able to behave like a protein in that it has enzymatic activity. Thus it is possible that RNA was the primordial prebiotic molecule and that proteins and DNA evolved subsequently.
About the laureate
Thomas R. Cech was born in Chicago on December 8, 1947. He received his B.A. degree in chemistry from Grinnell College and his Ph.D. degree in chemistry from the University of California, Berkeley. His postdoctoral work in biology was conducted at the Massachusetts Institute of Technology. Since 2000, Thomas Cech has been President of the Howard Hughes Medical Institute (Chevy Chase, Maryland, USA). He still maintains his laboratory at the University of Colorado in Boulder, USA, where he is Distinguished Professor in the Department of Chemistry and Biochemistry. He was elected to the National Academy of Sciences in 1987 and received the Nobel Prize in Chemistry in 1989, together with Sidney Altman.