Cech, Thomas

K, in osteoclasts 619 Cations. See also Individual ions active transport 422 channels 421,422 Cat scratch disease 7 Cauliflower mosaic virus 247 CD (Cluster of Differentiation) 187,407 Cech, Thomas R. 84 CED-3 619 Cell(s)... 

Cech, Thomas V. Principles of Water Resources History, Development, Management, and Policy. 3d ed. 

Cech, Thomas Robert (b. 1947) American biochemist who showed the remarkable fact that a length of protein-free RNA could act as an enzyme for the cleaving and splicing of other RNA. This fact could explain much about the early evolution of organisms. Cech shared the 1989 Nobel Prize in chemistry with Sidney Altman. 

Sidney Altman (Yale Univer sity) and Thomas Cech (University of Colorado) shared the 1989 Nobel Prize in chemistry for showing that RNAs could function as biological catalysts... 

The discovery of nbozymes (Section 28 11) in the late 1970s and early 1980s by Sidney Altman of Yale University and Thomas Cech of the University of Colorado placed the RNA World idea on a more solid footing Altman and Cech independently discovered that RNA can catalyze the formation and cleavage of phosphodiester bonds—exactly the kinds of bonds that unite individual ribonucleotides in RNA That plus the recent discovery that ribosomal RNA cat alyzes the addition of ammo acids to the growing peptide chain in protein biosynthesis takes care of the most serious deficiencies in the RNA World model by providing precedents for the catalysis of biologi cal processes by RNA... 

The second dogma had to undergo drastic correction about ten years after the correction of the first Sidney Altman from Yale University and Thomas Cech from the University of Colorado at Boulder independently discovered enzymatically active ribonucleic acids in different RNA species. This new class of RNA was called ri-bozyme (from n/wnuclease and enzyme). It was now necessary to modify the second dogma as follows ... 

All four scientists whose work led to modification of the dogmas received the Nobel Prize. Thomas Cech (1987) was the first to observe enzyme-like reactions taking place at the same RNA strand, in ribosomal RNA (rRNA) from the proto-zoon Tetrahymena thermophila. The RNA produced, which is completely viable, is formed in a process in which certain sections (introns) of the primary copy (the transcription of DNA to mRNA) are cut out, the two remaining ends of the exon then being rejoined (spliced). 

Essentially all biological catalysts in the modern world are themselves proteins, enzymes. However, in 1989 Sidney Altman and Thomas Cech received the Nobel prize in chemistry for showing that RNA itself could act as a catalyst for some biological reactions. This led to the idea that in an earlier time, as life was evolving, RNA may have been both the information molecule (a role usually played by the more stable DNA now) and the catalyst (the role that protein enzymes now play.) Since this idea indicates that in early times the synthesis of proteins was catalyzed by RNA, not by protein enzymes, the intriguing question is whether this is still true today. 

Sidney Altman and Thomas R. Cech Chemistry Catalytic RNA... 

Find two recent research articles published by Thomas R. Cech, who won the Nobel Prize for the discovery of ribozymes. Write brief summaries of the articles. 

CECH, R, THOMAS (1947-). Awarded the Nobel prize for chemistry in 1989 jointly with Sidney Altman for the discovery that RNA acts as a biological catalyst, as well as a carrier of genetic information. His Docloraie was awarded in 1975 by the University of California. 

We thank the Nobel Foundation for letting us reproduce their photographs of Melvin Calvin, Tom Cech, Edward Lewis, Thomas Hunt Morgan, Erwin Neher, Christiane Nusslein-Volhard, Bert Sakmann, Hans Spemann and Eric Weischaus. Photographs of Frederick Steward (Annu. Rev. Plant Physiol. 12, 1971) and Dan Koshland (Annu. Rev. Biochem. 65, 1996) are reproduced with permission from Annual Reviews Inc. 

In 1989, Sidney Altman and Thomas Cech were awarded the Nobel Prize in chemistry for a discovery that changed not only the field of biocatalysis, but also our perception of the molecular basis of life on Earth [118]. They showed that RNA, which until then was considered an innocent carrier of hereditary information, can actually catalyze reactions [119,120]. Two different RNA molecules were shown to catalyze site-specificphosphodiesterbondcleavage,withrate enhancements ofseveral orders of magnitude. This discovery of nonprotein biocatalysts came as a complete surprise, and laid open many questions and opportunities [121,122]. 

Thomas Cech and his coworkers discovered RNA catalysis in the early 1980 s while studying the removal of an intron from the riboso-mal RNA of a small ciliated protozoan, Tetrahymena. They established the reaction in vitro and then purified the components of the reaction mixture to isolate what they thought would be the enzyme responsible. To their surprise, they could remove all the detectable proteins from the mixture and still get intron removal to occur efficiently. 

An early hint of such a phenomenon occurred when the RNA cofactor of ribonuclease P was found capable of catalyzing the specific cleavage of pre-tRNAs in the absence of protein. However, the first real report of the ability of RNA to act as a catalyst was made from Thomas Cecil s laboratory in 1982, for which he subsequently shared the Nobel prize (1989). Cech and colleagues examined the removal... 

It was first discovered in 1981 by Thomas Cech and coworkers that a primary transcript for the 26 S rRNA from the protozoan Tetrarhymena could cut, splice, and assemble itself into the mature 26 S rRNA. Subsequently it was shown that a specific rRNA could catalyze the assembly of RNAs other than itself and that this could occur in the absence of any protein. Such enzyme-like RNAs were termed ribozymes. Self-splicing has been found to occur for RNAs from a variety of species. Two main types of self-splicing mechanisms are known ... 

Between 1981 and 1986, Thomas Cech and Sidney Altman discovered that there are at least two metabolic reactions where the catalysts are not proteins but RNAs. Up until then, it had been accepted that all enzymes are proteins, and normally the discovery of a few exceptions does not undermine a virtually universal rule, but those two examples had an extraordinary implication. 

Robert Holley (USA) Marshall Nirenberg (USA) (Nobel Prize, Medicine, 1968, genetic code protein synthesis) Sidney Altman Thomas Cech (USA, Nobel Prize, Chemistry, 1989, catalytic RNA)... 

The versatility of RNA first became clear from observations regarding the processing carried out on ribosomal RNA in a single-cell eukaryote. In Tetrahymena (a ciliated protozoan), a 414-nucleotide intron is removed from a 6.4-kb precursor to yield the mature 26S rRNA molecule (Figure 28.34). In an elegant series of studies of this splicing reaction, Thomas Cech and his coworkers established that the RNA spliced itself to precisely excise the 414-nucleotide intron. These remarkable experiments demonstrated that an RNA molecule can splice itself in the absence of protein and, indeed, can have highly specific catalytic activity. 

J. Michael Bishop, Harold E. Varmus, and Joseph E. Murray 1989 Sidney Altman and Thomas R. Cech... 

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