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Wednesday, December 10, 2008

Nobel Laureate: Walter Gilbert


The Nobel Prize in Chemistry 1980.

"for their contributions concerning the determination of base sequences in nucleic acids"

Walter Gilbert (1932 - ) was awarded the Nobel Prize for developing a chemical method of sequencing DNA (with Allan Maxam). The method relied on chemical reactions that cleaved DNA at specific residues. By carrying out partial reactions where only one cleavage occurred in each DNA strand, it was possible to separate the cleavage products on an acrylamide gel and determine the position of each residue by the length of the fragment.

The chemical sequencing strategy has been replaced by the chain-termination technique of Fred Sanger who shared the Nobel Prize with Gilbert.

A brief description of DNA sequencing can be found on the Wikipedia site at DNA Sequencing.

On looking over the 1980 press release I came across this paragraph.

Nobel Laureates
Gilbert and Sanger have independently developed different methods to determine the exact sequence of the nucleotide building blocks in DNA. Among applications of sequence methods may be mentioned that Gilbert has investigated the structure of those parts of a bacterial chromosome which control the reading (transcription) of the genetic message. Sanger is responsible for the first complete determination of the sequence of a DNA molecule. He has established the sequence of the 5375 building blocks in DNA from a bacterial virus called phi-X174. Sanger's method has also been used to determine the sequence of DNA from humans, which led to the surprising discovery that the genetic code is not universal, i.e. it is not the same in all living organisms, from viruses and bacteria to man.
I have no idea what they are referring to here when they mention the non-universality of the genetic code. I don't recall any revelations back in 1980. Are they referring to slight differences in mitochondria?

The images of the Nobel Prize medals are registered trademarks of the Nobel Foundation (© The Nobel Foundation). They are used here, with permission, for educational purposes only.

[Photo Credit: NNDB, original source unknown.]


  1. Sanger had a few publication on the genetic code used in human mitochondria, although after the cited laudatio:

    Anderson S, Bankier AT, Barrell BG, de Bruijn MH, Coulson AR, Drouin J, Eperon IC, Nierlich DP, Roe BA, Sanger F, Schreier PH, Smith AJ, Staden R, Young IG (1981):
    Sequence and organization of the human mitochondrial genome.
    Nature 290(5806):457-65

  2. My guess would be for mitochondria as well; the announcement was, I think, just pre-laureate, although Sanger wasn't an author (*). I'm not aware of any other different codes published before that, but then I was about six years old, so my molecular biology wasn't all it could have been...

    * Barrell et al. (1979) A different genetic code in human mitochondria, Nature, 282; 189-194