MARSHALL WARREN NIRENBERG (1927-)

Marshall Nirenberg was born in New York City. When he was 12, he and his family moved to Orlando, Florida. His early interest in bird-watching led him to the science of biology. Nirenberg was able to explore the diverse ecology of Florida's wetlands. He also benefited from the instruction provided by professionals - museum curators, biochemists - who were at nearby World War II training camps.

In 1948, Nirenberg graduated from the University of Florida with a Bachelor of Science degree. He stayed at the University of Florida to complete a Master's degree in Zoology on the ecology and taxonomy of caddis flies.

Nirenberg then went to the University of Michigan and in 1957 finished his Ph.D. He had become more interested in the question of life itself and wanted to know the essence. His Ph.D. work on sugar transport in tumor cells reflected his interest in the chemistry of life.

After his Ph.D., Nirenberg went to the National Institutes of Health (NIH) for a 2-year postdoctoral fellowship at the American Cancer Society. In 1960, he accepted the position of research biochemist in the Section of Metabolic Enzymes at the NIH. Nirenberg had already begun working on the problem of how to decipher the RNA code.

In 1961, Nirenberg and J. H. Matthaei published their landmark paper in Proceedings of the National Academy of Science. They showed that a synthetic messenger RNA made of only uracils can direct protein synthesis. The polyU mRNA resulted in a poly-phenylalanine protein ? they had the first piece of the genetic code.

In subsequent years, Nirenberg and his group deciphered the entire genetic code by matching amino acids to synthetic triplet nucleotides. They found that there is redundancy in that some amino acids are encoded by more than one codon and some codons are "punctuation marks" in the mRNA message. Nirenberg and his group also showed that with few exceptions, the genetic code was universal to all life on earth. Nirenberg shared the 1968 Nobel Prize in Physiology or Medicine with Har Gobind Khorana and Robert Holley. Khorana also worked on cracking the genetic code; Holley was the first to sequence a tRNA and determine its structure.

Nirenberg's research now focuses on the development of the nervous system of Drosophila melanogaster. He runs a lab in the National Heart, Lung, and Blood Institute of the NIH. He is still passionate about research ? the joy of discovery and the wonder of Nature's plan.

HAR GOBIND KHORANA (1922-)

Har Khorana was born in Raipur, West Pakistan. His father was a clerk in the British Indian government. Although the family was not well-to-do, Khorana's father made sure that his children had an education.

Khorana went to Punjab University in Lahore and graduated with a Master of Science. In 1945, a fellowship from the government of India gave him the opportunity to study abroad. He went to the University of Liverpool where he obtained his doctorate.

Khorana spent the next few years doing post-doctorate work, first at the Eidgenössische Technische Hochschule in Zurich, then at Cambridge University with G. W. Kenner and Lord Alexander R. Todd. It was at Cambridge that Khorana developed an interest in proteins and nucleic acids.

In 1952, Khorana was offered a job at the University of British Columbia where he was able to work fairly independently on various research projects involving phosphate esters and nucleic acids. The work on the chemical synthesis of ribotrinucleotides for protein synthesis was initiated at this time.

In 1960, Khorana accepted a position in the Institute for Enzyme Research at the University of Wisconsin. He continued working on nucleotide synthesis and cracking the genetic code. For this work Khorana shared the 1968 Nobel Prize in Physiology or Medicine with Robert Holley and Marshall Nirenberg.

Since 1970, Khorana has been the Alfred P. Sloan Professor of Biology and Chemistry at the Massachusetts Institute of Technology.

Links

The American Scientist

Appearing in the January 1998 issue, the article The Invention of the Genetic Code reviews the main lines of thought leading up to the genetic code theory.

The Protein Machine

This program from the European Bioinformatics Institute (EBI) is a translation program that starts with a DNA sequence. You can input your own sequence or choose one from the databanks. The program also tests different reading frames and color-codes the protein product.

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