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Christopher Fields
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Bio::Tools::Analysis::Protein::HNN - a wrapper around the HNN protein secondary structure prediction server


  use   Bio::Tools::Analysis::Protein::HNN;
  #get a Bio::Seq or Bio::PrimarySeq
  use Bio::PrimarySeq;
  my $seq = Bio::PrimarySeq->new
       -primary_id=>'test'); # a Bio::PrimarySeqI object

  my $hnn = Bio::Tools::Analysis::Protein::HNN->new (-seq=>$seq);
  print $hnn->result;# #raw text to standard error


A module to remotely retrieve predictions of protein secondary structure. Each residue in the protein receives a score representing the likelihood of existing in each of three different states (helix, coil or sheet), e.g.:

  my $analysis_object = Bio::Tools::SimpleAnalysis::Protein::HNN->new
     (-seq => $seq);

creates a new object


submits the query to the server and obtains raw text output.

Given an amino acid sequence the results can be obtained in 4 formats, determined by the argument to the result method:

  1. The raw text of the program output.

      my $rawdata = $analysis_object->result;                               
  2. A reference to an array of hashes of scores for each state and the assigned state.

      my $data_ref = $analysis_object->result('parsed');                                    
      print "score for helix at residue 2 is $data_ref->[1]{'helix'}\n";    
      print "predicted struc  at residue 2 is $data_ref->[1]{'struc}\n";
  3. An array of Bio::SeqFeature::Generic objects where each feature is a predicted unit of secondary structure. Only stretches of helix/sheet predictions for longer than 4 residues are defined as helices.

      my @fts = $analysis_object->result(Bio::SeqFeatureI);
      for my $ft (@fts) {           
          print " From ",  $ft->start, " to  ",$ft->end, " struc: " ,
                 ($ft->each_tag_value('type'))[0]  ,"\n";
  4. A Bio::Seq::Meta::Array implementing sequence.

    This is a Bio::Seq object that can also hold data about each residue in the sequence In this case, the sequence can be associated with a single array of HNN prediction scores. e.g.,

      my $meta_sequence = $analysis_object->result('meta');
      print "helix scores from residues 10-20 are ",
          $meta_sequence->named_submeta_text("HNN_helix",10,20), "\n";

    Meta sequence default names are : HNN_helix, HNN_sheet, HNN_coil, HNN_struc, representing the scores for each residue.

    Many methods common to all analyses are inherited from Bio::Tools::Analysis::SimpleAnalysisBase.


Bio::SimpleAnalysisI, Bio::Tools::Analysis::SimpleAnalysisBase, Bio::Seq::Meta::Array, Bio::WebAgent


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  bioperl-l@bioperl.org                  - General discussion
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Reporting Bugs

Report bugs to the Bioperl bug tracking system to help us keep track the bugs and their resolution. Bug reports can be submitted via the web:



Richard Adams, Richard.Adams@ed.ac.uk,


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


 NAme    : result
 Usage   : $job->result (...)
 Returns : a result created by running an analysis
 Args    : see keys of $INPUT_SPEC

The method returns a result of an executed job. If the job was terminated by an error the result may contain an error message instead of the real data.

This implementation returns differently processed data depending on argument:


Returns the raw ASCII data stream but without HTML tags.


The argument string defines the type of bioperl objects returned in an array. The objects are Bio::SeqFeature::Generic. Feature primary tag is "2ary". Feature tags are "type" (which can be helix, sheet or coil) "method" (HNN).


Array of hash references of scores/structure assignations { helix =>, sheet => , coil => , struc=>}.


A Bio::Seq::Meta::Array object. Scores can be accessed using methods from this class. Meta sequence names are HNN_helix, HNN_sheet, HNN_coil, HNN_struc.