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Wednesday, October 01, 2008

Nobel Laureate: Severo Ochoa


The Nobel Prize in Physiology or Medicine 1959.
"for their discovery of the mechanisms in the biological synthesis of ribonucleic acid and deoxyribonucleic acid"

Severo Ochoa (1905 -1993 ) received the Nobel Prize in Physiology or Medicine for his discovery of an enzyme that synthesizes RNA from ribonucleotide triphosphates. The enzyme, polynucleotide phosphorylase [Monday's Molecule #90], was first isolated from the bacterium Azotobacter vinelandii. At the time it was thought to be the enzyme responsible for the synthesis of RNA in cells as described in the excerpt from the presentation speech below from the Nobel Prize website [1959 Presentation Speech].

Ochoa shared his prize with Arthur Kornberg who discovered a DNA polymerase [Nobel Laureate: Arthur Kornberg].

Nobel Laureates
Ochoa's enzyme produces ribonucleic acids from ribonucleotides having twice the ratio of phosphoric acid residues as that contained in ribonucleic acid. The ribonucleic acid is formed by splitting out half of the phosphoric acid residues, and linking the nucleotides together to form large molecules, which, as far as we can prove today, do not differ in any way from natural nucleic acids. Kornberg's enzyme produces deoxyribonucleic acids in a similar, but not identical fashion. Both have arrived at the same, principally important result that in order to make the reaction start, it is necessary to add in the beginning a small amount of nucleic acid to act as a template. Otherwise the enzymes do not «know» which kind of nucleic acid they are to produce. As soon as they get a template to act as a guide, they start, just like a skilled type-setter, to copy the «manuscript» they have received. Here one recognizes life's own principle that like creates like. Even though several research workers had earlier suspected that such a mechanism was involved, the actual experimental proof is of greatest importance. Furthermore, Ochoa's enzyme has given us the possibility of enzymatically synthesizing simplified nucleic acids of great interest
Within a short time, scientists began to realize that polynucleotide phosphorylase did not require a DNA template. The enzyme synthesized random polymers of ribonucleotides in a reaction that is now recognized as a way of salvaging RNA in bacterial cells.

Within a few years Marshall Nirenberg, Gobind Khorana, and others began to exploit this enzyme to synthesize synthetic RNAs that were used to crack the genetic code [Nobel Laureates: Robert W. Holley, Har Gobind Khorana, and Marshall W. Nirenberg].

This is one example of a Nobel Prize that was awarded for the wrong reasons but few people begrudge Ochoa since he was widely recognized as an outstanding scientist. Arthur Kornberg worked with him for one year (1946) in New York where he (Kornberg) purified his first enzymes and fell in love with enzymes (Kornberg, 2001).

Ochoa was born in Spain and graduated from the University of Madrid with an M.D. degree in about 1925. He worked with Otto Meyerhof [Nobel Laureates: Otto Fritz Meyerhof] for a few years on metabolic enzymes before joining a series of labs in Europe. Eventually the civil war in Spain and the outbreak of World War II in Europe led him to join Carl and Gerty Cori in St. Louis, Missouri (USA) in 1942 [Nobel Laureates: Carl Ferdinand Cori and Gerty Theresa Cori]. From there he moved to New York University School of Medicine where he remained until his retirement in 1974.

Ochoa did not return to Spain until the year Franco died (1975). He celebrated his 70th birthday in spectacular manner according to Arthur Kornberg (Kornberg, 2001).
To celebrate his 70th birthday in 1975, Ochoa chose as guests the scientists he most respected worldwide. Symposia and celebratory dinners, starting in Barcelona, were followed by a visit with Salvador Dali in his museum in his hometown in Figueras and culminated in a gala of events in Madrid. It was a party, the likes of which has not been seen in scientific circles before or since.

[Photo Credits: Top: Kornberg (2001), Bottom: Severo Ochoa: La Conquista del Nobel]

Kornberg, A. (2001) Remembering Our Teachers. J. Biol. Chem. 276:3-11. [JBC Online]

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