Frequency/distribution of nucleotides/amino acids before selection

Jean Lobry lobry at acnuc.univ-lyon1.fr
Tue Oct 27 11:10:36 EST 1998


On Wed, 21 Oct 1998 17:53:14, Dr.Ram Samudrala <ram.samudrala at stanford.nojunkemail> 
wrote:
>
> Have there been any estimates published on the frequency/distribution
> of nucleotides/amino acids in DNA/protein sequences PRIOR to
> selection, i.e., before selection kicks in? I can get the frequencies
> of amino acids in known protein sequences, but these proteins have
> generally arisen through natural selection.
>

I'am not sure that this answers your question but in

  Lobry, J.R. (1997) Influence of genomic G+C content on average amino-acid
  composition of proteins from 59 bacterial species. Gene 205:309-316

you find how to compute theoretical amino-acid frequencies as function of
nucleotidic frequencies in absence of selection. This is not difficult,
you just have to take care that there are no stop codons in coding sequences.

Jean Lobry

============================================================
Jean R. Lobry (lobry at biomserv.univ-lyon1.fr)
Laboratoire BGBP-CNRS-UMR-5558, Univ. C. Bernard - LYON I, 
43 Bd 11/11/1918, F-69622 VILLEURBANNE CEDEX, FRANCE
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