Bio::Tools::IUPAC - Generates unique sequence objects or regular expressions from an ambiguous IUPAC sequence


 use Bio::PrimarySeq;
 use Bio::Tools::IUPAC;

 # Get the IUPAC code for proteins
 my %iupac_prot = Bio::Tools::IUPAC->new->iupac_iup;

 # Create a sequence with degenerate residues
 my $ambiseq = Bio::PrimarySeq->new(-seq => 'ARTCGUTGN', -alphabet => 'dna');

 # Create all possible non-degenerate sequences
 my $iupac = Bio::Tools::IUPAC->new(-seq => $ambiseq);
 while ($uniqueseq = $iupac->next_seq()) {
     # process the unique Bio::Seq object.

 # Get a regular expression that matches all possible sequences
 my $regexp = $iupac->regexp();


Bio::Tools::IUPAC is a tool that manipulates sequences with ambiguous residues following the IUPAC conventions. Non-standard characters have the meaning described below:

      Cornish-Bowden (1985) Nucl. Acids Res. 13: 3021-3030

    Symbol       Meaning      Nucleic Acid
     A            A           Adenine
     C            C           Cytosine
     G            G           Guanine
     T            T           Thymine
     U            U           Uracil
     M          A or C        aMino
     R          A or G        puRine
     W          A or T        Weak
     S          C or G        Strong
     Y          C or T        pYrimidine
     K          G or T        Keto
     V        A or C or G     not T (closest unused char after T)
     H        A or C or T     not G (closest unused char after G)
     D        A or G or T     not C (closest unused char after C)
     B        C or G or T     not A (closest unused char after A)
     X      G or A or T or C  Unknown (very rarely used)
     N      G or A or T or C  Unknown (commonly used)

      Biochem J. 1984 Apr 15; 219(2): 345-373
      Eur J Biochem. 1993 Apr 1; 213(1): 2

    Symbol           Meaning
    A        Alanine
    B        Aspartic Acid, Asparagine
    C        Cysteine
    D        Aspartic Acid
    E        Glutamic Acid
    F        Phenylalanine
    G        Glycine
    H        Histidine
    I        Isoleucine
    J        Isoleucine/Leucine
    K        Lysine
    L        Leucine
    M        Methionine
    N        Asparagine
    O        Pyrrolysine
    P        Proline
    Q        Glutamine
    R        Arginine
    S        Serine
    T        Threonine
    U        Selenocysteine
    V        Valine
    W        Tryptophan
    X        Unknown
    Y        Tyrosine
    Z        Glutamic Acid, Glutamine
    *        Terminator

There are a few things Bio::Tools::IUPAC can do for you:

  • report the IUPAC mapping between ambiguous and non-ambiguous residues

  • produce a stream of all possible corresponding unambiguous Bio::Seq objects given an ambiguous sequence object

  • convert an ambiguous sequence object to a corresponding regular expression


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AUTHOR - Aaron Mackey



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


 Title   : new
 Usage   : Bio::Tools::IUPAC->new($seq);
 Function: Create a new IUPAC object, which acts as a sequence stream (akin to
 Args    : an ambiguously coded sequence object that has a specified 'alphabet'
 Returns : a Bio::Tools::IUPAC object.


 Title   : next_seq
 Usage   : $iupac->next_seq();
 Function: returns the next unique sequence object
 Args    : none.
 Returns : a Bio::Seq object


 Title   : iupac
 Usage   : my %symbols = $iupac->iupac;
 Function: Returns a hash of symbols -> symbol components of the right type
           for the given sequence, i.e. it is the same as iupac_iup() if
           Bio::Tools::IUPAC was given a proteic sequence, or iupac_iub() if the 
           sequence was nucleic. For example, the key 'M' has the value ['A', 'C'].
 Args    : none
 Returns : Hash


 Title   : iupac_amb
 Usage   : my %symbols = $iupac->iupac_amb;
 Function: Same as iupac() but only contains a mapping between ambiguous residues
           and the ambiguous residues they map to. For example, the key 'N' has
           the value ['R', 'Y', 'K', 'M', 'S', 'W', 'B', 'D', 'H', 'V', 'N'],
           i.e. it matches all other ambiguous residues.
 Args    : none
 Returns : Hash


 Title   : iupac_iup
 Usage   : my %aasymbols = $iupac->iupac_iup;
 Function: Returns a hash of PROTEIN symbols -> non-ambiguous symbol components
 Args    : none
 Returns : Hash


 Title   : iupac_iup_amb
 Usage   : my %aasymbols = $iupac->iupac_iup_amb;
 Function: Returns a hash of PROTEIN symbols -> ambiguous symbol components
 Args    : none
 Returns : Hash


 Title   : iupac_iub
 Usage   : my %dnasymbols = $iupac->iupac_iub;
 Function: Returns a hash of DNA symbols -> non-ambiguous symbol components
 Args    : none
 Returns : Hash


 Title   : iupac_iub_amb
 Usage   : my %dnasymbols = $iupac->iupac_iub;
 Function: Returns a hash of DNA symbols -> ambiguous symbol components
 Args    : none
 Returns : Hash


 Title   : iupac_rev_iub
 Usage   : my %dnasymbols = $iupac->iupac_rev_iub;
 Function: Returns a hash of nucleotide combinations -> IUPAC code
           (a reverse of the iupac_iub hash).
 Args    : none
 Returns : Hash


 Title   : count
 Usage   : my $total = $iupac->count();
 Function: Calculates the number of unique, unambiguous sequences that
           this ambiguous sequence could generate
 Args    : none
 Return  : int


 Title   : regexp
 Usage   : my $re = $iupac->regexp();
 Function: Converts the ambiguous sequence into a regular expression that
           matches all of the corresponding ambiguous and non-ambiguous sequences.
           You can further manipulate the resulting regular expression with the
           Bio::Tools::SeqPattern module. After you are done building your
           regular expression, you might want to compile it and make it case-
              $re = qr/$re/i;
 Args    : 1 to match RNA: T and U characters will match interchangeably
 Return  : regular expression