NAME

Bio::PDB::Structure - Perl module for parsing and manipulating Protein Databank (PDB) files

SYNOPSIS

use Bio::PDB::Structure;

$mol1= Bio::PDB::Structure::Molecule -> new;
$mol2= Bio::PDB::Structure::Molecule -> new;
$mol1 -> read("molecule.pdb",0);         #read the first model
$mol2 -> read("molecule.pdb",1);         #read the second model
$mol1b = $mol1 -> backbone;              #create a list with the backbone of mol1
$mol2b = $mol2 -> backbone;              #create a list with the backbone of mol2
@transform = $mol2b ->superpose($mol1b); #compute alignment of mol2 to mol1
$mol2 ->rotate_translate(@transform);    #rotate and translate mol2
$rmsd = $mol2 -> rmsd($mol1);            #compute the rmsd between mol2 and mol1
$mol2 -> print("new.pdb");               #save the molecule to a file

DESCRIPTION

This module combines tools that are commonly used to analyze proteins and nucleic acids from a pdb file stuctures. The main benefits of using the module are its ability to parse and print out a pdb structure with minimum effort. However in addition to that it is possible to do structural alignments, RMSD calculations, atom editons, center of mass calculations, molecule editions and so forth. Both Atom objects and Molecule objects are defined within this module.

Methods for Atom objects

• $object->type

• $object->type("ATOM")

  Get/set the atom's type

• $object->number

• $object->number(50)

  Get/set the atom's number

• $object->name

• $object->name("CA")

  Get/set the atom's name

• $object->chain

• $object->chaini("X")

  Get/set the atom's chain 

• $object->chain

• $object->residue_number(100)

  Get/set the atom's residue number 

• $object->residue_name

• $object->residue_name("ALA")

  Get/set the atom's residue name 

• $object->x

• $object->x(5.5)

  Get/set the atom's x coordinate 

• $object->y

• $object->y(5.5)

  Get/set the atom's y coordinate 

• $object->z

• $object->z(5.5)

  Get/set the atom's z coordinate 

• $object->occupancy

• $object->occupancy(1.0)

  Get/set the atom's occupancy

• $object->beta

• $object->beta(0.3)

  Get/set the atom's temperature factor

• $object->alt

• $object->alt("I")

  Get/set the atom's alternate location field

• $object->insertion_code

• $object->insertion_code("K")

  Get/set the atom's insertion code

• distance Bio::PDB::Structure::Atom($atom1,$atom2)

  Compute the distance between atom1 and atom2

• distance Bio::PDB::Structure::Atom($atom1,$atom2,$atom3)

  Compute the angle in degrees sustended by  atom1--atom2--atom3

• dihedral Bio::PDB::Structure::Atom($atom1,$atom2,$atom3,$atom4)

  Compute the dihedral in degrees sustended by atom1--atom2--atom3--atom4

Methods for Molecule objects

• models Bio::PDB::Structure::Molecule "file.pdb"

  Return the number of models in a pdb file

• $object->read("file.pdb")

• $object->read("file.pdb",i)

  Read the contents of file.pdb into a molecule. If a second numeric argument is
  specified it will read  model (i+1) from the file  (counting from zero).

• $object->print

• $object->print("file.pdb")

  Write the molecule to STDOUT when no argument is provided or to a file when an
  argument is provided.

• $object->size

  Return the number of atoms contained in the molecule.

• $object->atom(5)

  Return the atom located at position five (starting from zero).

• $object->push(atom)

  Push atom object at the end of the molecule.

• $object->proten

  Return a molecule that only contains atoms with type ATOM

• $object->hetatoms

  Retruns a molecule that only contains HETATM records

• $object->alpha

  Returns a molecule with the alpha carbons

• $object->backbone

  Returns a molecule with the backbone of a protein

• $object->sidechains

  Returns a molecule with the sidechains of a protein

• $object->list_atoms('logical expression')

  Creates a molecule with a custom atom selection. The logical expression must use
  Perl's logical operators and the properties of atoms. For example to select all
  atoms from residue 50 onwards and only belonging to ALA residues on would use
  the logical expression: 'residue_number >= 50 && residue_name eq "ALA"'

• $object->center

  Return an atom object that respresents the centroid for the given molecule.

• $object->cm

  Return an atom object that sits at the center of mass for the given molecule.

• $object->translate(x,y,z)

  Translate the molecule as a rigid object by x,y,z.

• $object->rotate(u11,u12,u13,u21,u22,u23,u31,u32,u33)

  Do a rigid rotation of the molecule using matrix u.

• $object->rotate_translate(@matrix,@vector)

  Apply a rotation matrix followed by a translation. To facilitate structural
  supperpositions.

• $object->superpose($reference)

  Find the transformation that overlaps $object on to $reference. The resulting
  transformation is in the format @transformation= (@matrix,@vector). Molecules
  must have the same number of atoms.

• $object->rmsd($reference)

  Compute the RMSD between two molecules. The molecules must have the same number
  of atoms

SEE ALSO

http://www.pdb.org

AUTHOR

Raul Alcantara Aragon, <rulix@hotmail.com>

COPYRIGHT AND LICENSE

Copyright (C) 2012 by Raul Alcantara

This library is free software; you can redistribute it and/or modify it under the same terms as Perl itself, either Perl version 5.12.3 or, at your option, any later version of Perl 5 you may have available.