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|religion = |footnotes = |signature = |spouse=Perola Zaltzman-Nirenberg (1961-2001; her death) Myrna M. Weissman (m. 2005) }} Marshall Warren Nirenberg (April 10, 1927 – January 15, 2010) was an American biochemist and geneticist. He shared a Nobel Prize in Physiology or Medicine in 1968 with Har Gobind Khorana and Robert W. Holley for "breaking the genetic code" and describing how it operates in protein synthesis. In the same year, together with Har Gobind Khorana, he was awarded the Louisa Gross Horwitz Prize from Columbia University. ==Research== By 1959, experiments and analysis such as the Avery–MacLeod–McCarty experiment, the Hershey–Chase experiment, the Watson–Crick structure and the Meselson–Stahl experiment had shown DNA to be the molecule of genetic information. It was not known, however, how DNA directed the expression of proteins, or what role RNA had in these processes. Nirenberg teamed up with Heinrich J. Matthaei at the National Institutes of Health to answer these questions. They produced RNA composed solely of uracil, a nucleotide that only occurs in RNA. They then added this synthetic poly-uracil RNA into a cell-free extract of ''Escherichia coli'' which contained the DNA, RNA, ribosomes and other cellular machinery for protein synthesis. They added DNase, which breaks apart the DNA, so that no additional proteins would be produced other than that from their synthetic RNA. They then added 1 radioactively labeled amino acid, the building blocks of proteins, and 19 unlabeled amino acids to the extract, varying the labeled amino acid in each sample. Only in the extract containing the radioactively labeled phenylalanine, was the resulting protein also radioactive. This implied that the genetic code for phenylalanine on RNA consisted of a repetition of uracil bases. Indeed, as we know now, it is UUU (three uracil bases in a row). This was the first step in deciphering the codons of the genetic code and the first demonstration of messenger RNA (''see Nirenberg and Matthaei experiment''). In August 1961, at the International Congress of Biochemistry in Moscow, Nirenberg presented a paper to a small group of scientists. Francis Crick convinced the conference leaders to invite Nirenberg to repeat his performance the next day. Speaking before the assembled congress of more than a thousand people, Nirenberg electrified the scientific community. He quickly received great scientific attention for these experiments. Within a few years, his research team had performed similar experiments and found that three-base repeats of adenosine (AAA) produced the amino acid lysine, and cytosine repeats (CCC) produced proline. The next breakthrough came when Philip Leder, a postdoctoral researcher in Nirenberg's lab, developed a method for determining the genetic code on pieces of tRNA (''see Nirenberg and Leder experiment''). This greatly sped up the assignment of three-base codons to amino acids so that 50 codons were identified in this way. Khorana's experiments confirmed these results and completed the genetic code translation. The period between 1961 and 1962 is often referred to as the "coding race" because of the competition between the labs of Nirenberg at NIH and Nobel laureate Severo Ochoa at New York University Medical School, who had a massive staff. Faced with the possibility of helping the first NIH scientist win a Nobel prize, many NIH scientists put aside their own work to help Nirenberg in deciphering the mRNA codons for amino acids. Dr. DeWitt Stetten, Jr., director of the National Institute of Arthritis and Metabolic Diseases, called this period of collaboration "NIH's finest hour".〔(The PolyU Experiment ). history.nih.gov〕 Nirenberg's later research focused on neuroscience, neural development, and the homeobox genes. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Marshall Warren Nirenberg」の詳細全文を読む スポンサード リンク
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