Altman, Sidney

Alternative splicing of proteins 538 Altman, Sidney 84 Altrose (Alt) 163s Aluminum... 

ALTMAN, SIDNEY (1939-). Awarded the Nobel prize in Chemistry in 1989 jointly with Thomas R. Cecil for the discovery that RNA acts as a biological catalyst as well as a carrier of genetic information. He received his Doctorate in 1967 from the University of Colorado. 

Altman, Sidney Fiedler, Paul Levine, Robert A. Wardlaw, Stephen C. USA Conjugates Intercalating functional groups attached to oligonucleotides WO9604788 1996... 

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 ... 

Sidney Altman discovered this property of RNA in the course of studies on precursor transfer RNA. It was realized that the catalytic properties of RNA are not exactly the same as those of protein enzymes, since the ribozyme is itself active and thus undergoes change during the catalytic reaction. This does not correspond to the generally accepted definition of an enzyme. Later studies, however, showed that some ribozymes are capable of acting catalytically at other RNA molecules. The ribozymes remain completely unchanged in this process, and thus fulfil the definition of a real enzyme. 

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. 

Many years later, Tom Cech and Sidney Altman established that there is a second class of catalytic entities in living systems that are nucleic acid in nature the ribozymes. 1 get around to these in a later chapter. 

Sidney Altman United States, b. Canada catalytic properties of RNA... 

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

A very different ribonuclease participates in the biosynthesis of all of the transfer RNAs of E. coli. Ribonuclease P cuts a 5 leader sequence from precursor RNAs to form the final 5 termini of the tRNAs. Sidney Altman and coworkers in 1980 showed that the enzyme consists of a 13.7-kDa protein together with a specific 377-nucleotide RNA component (designated Ml RNA) that is about five times more massive than the protein.779 Amazingly, the Ml RNA alone is able to catalyze the ribonuclease reaction with the proper substrate specificity.780 7823 The protein apparently accelerates the reaction only about twofold for some substrates but much more for certain natural substrates. The catalytic center is in the RNA, which functions well only in a high salt concentration. A major role of the small protein subunit may be to provide counterions to screen the negative charges on the RNA and permit rapid binding of substrate and release of products.783 Eukaryotes, as well as other prokaryotes, have enzymes similar to the E. coli RNase R However, the eukaryotic enzymes require the protein part as well as the RNA for activity.784... 

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]. 

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 development of capabilities beyond simple replication required the generation of specific catalysts. A catalyst is a molecule that accelerates a particular chemical reaction without itself being chemically altered in the process. The properties of catalysts will be discussed in detail in Chapters 8 and 9. Some catalysts are highly specific they promote certain reactions without substantially affecting closely related processes. Such catalysts allow the reactions of specific pathways to take place in preference to those of potential alternative pathways. Until the 1980s, all biological catalysts, termed enzymes, were believed to be proteins. Then, Tom Cech and Sidney Altman independently discovered that certain RNA molecules can be effective catalysts. These RNA catalysts have come to be known as ribozymes. The discovery of ribozymes suggested the possibility that catalytic RNA molecules could have played fundamental roles early in the evolution of life. 

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

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