Answers.Body: <p>Although there is not a unique nucleotide sequence that translates to a given protein, one can list all the possible DNA sequences that do translate to that protein.</p>
  
  <p>An online tool that does just that is <a href="https://www.ebi.ac.uk/Tools/st/emboss_backtranambig/" rel="noreferrer">Backtranambig</a>, from EMBOSS. It produces a DNA sequence representing all the nucleotide sequences matching the input protein, using <a href="https://droog.gs.washington.edu/parc/images/iupac.html" rel="noreferrer">IUPAC ambiguity codes</a>.</p>
  
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Answers.UserDisplayName: PedroSebe
Answers.Body: <p><a href="https://edinburgh-genome-foundry.github.io/DnaChisel/index.html" rel="nofollow noreferrer">DNA Chisel</a> (written in Python) can <a href="https://edinburgh-genome-foundry.github.io/DnaChisel/ref/biotools.html?highlight=reverse_translate#dnachisel.biotools.reverse_translate" rel="nofollow noreferrer">reverse translate</a> a protein sequence:</p>
  <pre class="lang-py prettyprint-override"><code>import dnachisel
  from dnachisel.biotools import reverse_translate
  
  record = dnachisel.load_record(&quot;seq.fa&quot;)
  reverse_translate(str(record.seq))
  # GGTCATATTTTAAAAATGTTTCCT
  </code></pre>
  
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Answers.Body: <p>You can't do this because there is redundancy in the genetic code and the <em>same</em> protein sequences can be encoded by <em>different</em> nucleotide sequences. There are 64 codons and ~20 amino acids, e.g. <code>GCT</code>, <code>GCC</code>, <code>GCA</code> and <code>GCG</code> all encode Alanine.</p>
  
  
  
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Answers.Text: For the sake of the programming exercise, one could use IUPAC ambiguity codes to reflect the set of possible codons for a given amino-acid.
Answers.UserDisplayName: bli
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Answers.Text: @bli Agreed, one could even build a model to predict the underlying codons since there is codon usage bias. For practical purposes I'd do a TBLASTN against NT or similar
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Body: <p>I want to convert a list of fasta ( protein sequences) in a .text file into corresponding nucleotide sequences. A Google search gives me result of DNA to protein conversion but not vice versa. Also, I came across How do I find the nucleotide sequence of a protein using Biopython?, but this is what I am not looking for. Is there any possible way to do it using python.Moreover, I would like to solve it using python programming. I am sure there must be some way to do it rather than writing a code from scratch. Thanks!</p>
  
Tags: <proteins><python><phylogenetics><sequence>
Title: How to translate amino acid sequences to Nucleotide sequences
ThreadText: # How to translate amino acid sequences to Nucleotide sequences
  
  (Asked by: username_0 on 2020-02-08)
  
  I want to convert a list of fasta ( protein sequences) in a .text file into corresponding nucleotide sequences. A Google search gives me result of DNA to protein conversion but not vice versa. Also, I came across How do I find the nucleotide sequence of a protein using Biopython?, but this is what I am not looking for. Is there any possible way to do it using python.Moreover, I would like to solve it using python programming. I am sure there must be some way to do it rather than writing a code from scratch. Thanks!
  
  **Tags:** proteins, python, phylogenetics, sequence
  
  
  ---
  
  ## 3 answers
  
  ### Answer by username_1 on 2020-02-09. Score: 5
  
  Although there is not a unique nucleotide sequence that translates to a given protein, one can list all the possible DNA sequences that do translate to that protein.
  
  An online tool that does just that is [Backtranambig](https://www.ebi.ac.uk/Tools/st/emboss_backtranambig/), from EMBOSS. It produces a DNA sequence representing all the nucleotide sequences matching the input protein, using [IUPAC ambiguity codes](https://droog.gs.washington.edu/parc/images/iupac.html).
  
  
  ---
  
  ### Answer by username_2 on 2020-11-23. Score: 2
  
  [DNA Chisel](https://edinburgh-genome-foundry.github.io/DnaChisel/index.html) (written in Python) can [reverse translate](https://edinburgh-genome-foundry.github.io/DnaChisel/ref/biotools.html?highlight=reverse_translate#dnachisel.biotools.reverse_translate) a protein sequence:
  
  ```py
  import dnachisel
  from dnachisel.biotools import reverse_translate
  
  record = dnachisel.load_record("seq.fa")
  reverse_translate(str(record.seq))
  # GGTCATATTTTAAAAATGTTTCCT
  
  ```
  
  
  ---
  
  ### Answer by username_3 on 2020-02-09. Score: 1
  
  You can't do this because there is redundancy in the genetic code and the *same* protein sequences can be encoded by *different* nucleotide sequences. There are 64 codons and ~20 amino acids, e.g. `GCT`, `GCC`, `GCA` and `GCG` all encode Alanine.
  
  > **Comments:**
  > **username_4**: For the sake of the programming exercise, one could use IUPAC ambiguity codes to reflect the set of possible codons for a given amino-acid.  
  > **username_3**: @username_4 Agreed, one could even build a model to predict the underlying codons since there is codon usage bias. For practical purposes I'd do a TBLASTN against NT or similar  
  
  ---
  
  