Ewan Birney


Bio::SeqUtils - Additional methods for PrimarySeq objects


    use Bio::SeqUtils;
    # get a Bio::PrimarySeqI compliant object, $seq, somehow
    $util = new Bio::SeqUtils;
    $polypeptide_3char = $util->seq3($seq);
    # or
    $polypeptide_3char = Bio::SeqUtils->seq3($seq);

    # set the sequence string (stored in one char code in the object)
    Bio::SeqUtils->seq3($seq, $polypeptide_3char);

    # translate a sequence in all six frames
    @seqs = Bio::SeqUtils->translate_6frames($seq);


This class is a holder of methods that work on Bio::PrimarySeqI- compliant sequence objects, e.g. Bio::PrimarySeq and Bio::Seq. These methods are not part of the Bio::PrimarySeqI interface and should in general not be essential to the primary function of sequence objects. If you are thinking of adding essential functions, it might be better to create your own sequence class. See Bio::PrimarySeqI, Bio::PrimarySeq, and Bio::Seq for more.

The methods take as their first argument a sequence object. It is possible to use methods without first creating a SeqUtils object, i.e. use it as an anonymous hash.

The first two methods, seq3() and seq3in(), give out or read in protein sequences coded in three letter IUPAC amino acid codes.

The next two methods, translate_3frames() and translate_6frames(), wrap around the standard translate method to give back an array of three forward or all six frame translations.


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AUTHOR - Heikki Lehvaslaiho

Email: heikki@ebi.ac.uk Address:

     EMBL Outstation, European Bioinformatics Institute
     Wellcome Trust Genome Campus, Hinxton
     Cambs. CB10 1SD, United Kingdom


The rest of the documentation details each of the object methods. Internal methods are usually preceded with a _


 Title   : seq3
 Usage   : $string = Bio::SeqUtils->seq3($seq)

           Read only method that returns the amino acid sequence as a
           string of three letter codes. alphabet has to be
           'protein'. Output follows the IUPAC standard plus 'Ter' for
           terminator. Any unknown character, including the default
           unknown character 'X', is changed into 'Xaa'. A noncoded
           aminoacid selenocystein is recognized (Sel, U).

 Returns : A scalar
 Args    : character used for stop in the protein sequence optional,
           defaults to '*' string used to separate the output amino
           acid codes, optional, defaults to ''


 Title   : seq3in
 Usage   : $string = Bio::SeqUtils->seq3in($seq, 'MetGlyTer')

           Method for in-place changing of the sequence of a
           Bio::PrimarySeqI sequence object. The three letter amino
           acid input string is converted into one letter code.  Any
           unknown character triplet, including the default 'Xaa', is
           converted into 'X'.

 Returns : Bio::PrimarySeq object;
 Args    : character to be used for stop in the protein seqence,
              optional, defaults to '*'
           character to be used for unknown in the protein seqence,
              optional, defaults to 'X'


 Title   : translate_3frames
 Usage   : @prots = Bio::SeqUtils->translate_3frames($seq)
 Function: Translate a nucleotide sequence in three forward frames.
           The IDs of the sequences are appended with '-0F', '-1F', '-2F'.
 Returns : An array of seq objects
 Args    : sequence object
           same arguments as to Bio::PrimarySeqI::translate


 Title   : translate_6frames
 Usage   : @prots = Bio::SeqUtils->translate_6frames($seq)
 Function: translate a nucleotide sequence in all six frames
           The IDs of the sequences are appended with '-0F', '-1F', '-2F',
           '-0R', '-1R', '-2R'.
 Returns : An array of seq objects
 Args    : sequence object
           same arguments as to Bio::PrimarySeqI::translate


 Title   : valid_aa
 Usage   : my @aa = $table->valid_aa
 Function: Retrieves a list of the valid amino acid codes
 Returns : array of all the valid amino acid codes
 Args    : [optional] $code => [0 -> return list of 1 letter aa codes,
                                1 -> return list of 3 letter aa codes,
                                2 -> return associative array of both ]