|
|||||
![]() |
![]() |
![]() |
![]() |
![]() |
![]() |
Carbons in cycles can be tested for aromaticity. If the angle between the
normals to adjacent atoms in the cycle is less than 7.5 Degrees, the
cycle is considered aromatic: its carbons are renamed "A.." and their
element type set to 'A'. (This is for the force-field calculations done
in AutoDock.) This Module does this conversion reversibly. Also, the user
is able to select a carbon to convert (reversibly).
Non-polar hydrogens can be merged which means that the charge of each is
added to its carbon and the hydrogen atoms themselves are not written in
the output file, thus in some sense 'removing' them from the molecule.
'Fewer' atoms simplifies the AutoDock run.
The last function of this Module is to write a file which contains the
correctly formatted ligand atoms. The ROOT section of the molecule
expands from the selected ROOT atom out to include all atoms adjacent to
it up to the first active torsion. The active torsions set the position
of BRANCH and TORS key words in the output pdbq file (and their
corresponding ENDBRANCH and ENDTORS key words). These keywords are nested
to set up a Depth-First Order Traversal. Autotors also calculates the
torsional degrees of freedom (TORSDOF) which is the number of possible
torsions less the number of symmetry-equivalent torsions (such as a bond
to a NH3). This key word is the last line of the pdbq file.
The user can select the macromolecule for autogpf in three ways:
The user can set the types of maps to be generated by AutoGrid :
At the same time the user sets the types of maps to be calculated, he
decides which types of hydrogen bonding he wishes to model. For
instance, if hydrogens are present AND nitrogens, oxygens and /or
sulfurs, the user can decide to model N-H bonds, O-H bonds and/or S-H
bonds. (Obviously, if there are no hydrogens present in the ligand, no
hydrogen bonding should be modeled.)
The grid:
The user positions the grid and sets its dimensions by:
The results of the previous steps are written to a file. The user selects a
filename via a filebrowser. By convention, the file should have a .gpf
extension. If no macromolecule has been selected, it is not possible to write
a grid parameter file and the user gets a warning message to that effect.
Likewise, the types of the maps to be calculated must be set before the grid
parameter file is written and a warning message to this effect appears if the
types have not been set. (A checkbutton, "DONE", allows the user to withdraw
the autoTools menuBar and geometries used by this module or the autotors such
as the box and spheres used to mark center of box if desired.)
Selecting the macromolecule filename:
The user can select the macromolecule for autodpf in three ways:
The user sets the parameters pertaining to the small molecule by :
The user sets parameters pertaining to docking algorithm(s) he wishes to use : o Setting Simulated Annealing parameters.
The results of the previous steps are written to a file. The user selects a
filename via a filebrowser. By convention, the file should have a .dpf
extension. If no macromolecule has been selected, it is not possible to write
a grid parameter file and the user gets a warning message to that effect.
Likewise, the types of the maps to be calculated must be set before the grid
parameter file is written and a warning message to this effect appears if the
types have not been set. (A checkbutton, "DONE", allows the user to withdraw
the autoTools menuBar)
The first step is the selection of the log file generated by an autodock job.
This module parses that file setting values in a dictionary 'docked' which is
an attribute of the molecular viewer.
The AutoTools suite provides a GUI for setting up and running docking
calculations using AutoDock
Autotors Commands:
This Module facilitates selecting and formatting a ligand for a subsequent
AutoDock run.
The steps in this process are:
The user selects the small molecule from a list of molecules already in
the moleculeViewer OR as a PDBQ file or as a MOL2 file from a fileBrowser
.
The user selects the ROOT atom of the ligand either:
by picking it
Next the user decides which possible and active torsions he wants to
disallow, changing them from active to inactive. This is done by picking
an active 'green' bond which turns it inactive or 'purple'. This is
reversible. The user can also disallow all peptide backbone torsions and/
or all torsions of amide bonds.
by autoroot which sets the root to be the atom in the molecule which
has the smallest 'largest sub-tree.'
Autogpf Commands:
This Module facilitates producing a grid parameter file for AutoGrid. The
steps in this process are:
Selecting the macromolecule:
it can be chosen from molecules previously added to the moleculeViewer
using the Choose Macromol... option
Selecting the types of maps to generate:
it can be read in from a PDB file using the Read PDB Macromolecule
option
it can be read in from a MOL2 file using the Read MOL2
Macromolecule option
by entering the types directly
If a ligand is chosen or read in from a file, the types of atoms in it
are then determined. If he wishes, the user can modify the set of atom
types found. (NB: entries are activated by clicking the 'Return' key)
by choosing a ligand
Set Map Types Directly
Setting the types of maps to be calculated:
Via Choosing Ligand
Via Reading PDBQ Ligand
Via Reading MOL2 Ligand
Setting the center of the grid maps:
Additional parameters that the user could adjust:
- by picking an atom
Setting the number of grid points in each direction (which has to be an
even number) and the spacing between the points. This is done by using
the corresponding scale widgets.
- by entering the full-name of an atom
- by entering the desired coordinates in entries 'x center', 'y
center', 'z center' (NB: ALL entries must be 'activated' by a
'Return')
- by choosing the 'autocenter' option which sets the center of the
grid to the geometric center of the macromolecule (obtained by
averaging all its coordinates)
Adjusting the position of the grid using scales for x-offset, y-offset
and z-offset. These scales allow the user to move the grid box up to 10
angstroms in any direction along any of the three axes. (NOTE that the
units of these scales are tenths of Angstroms and the new coordinates
of the center are reflected in the x-center, y-center, z-center entries)
The smoothing factor can be changed from its default 0.5 Angstrom value. This changes the radius of the area within which the minimum energy is stored.
The grid parameters file:
Electrostatic potential map may or may not be generated by AutoGrid.
Floating point potential map may or may not be generated
The user may decide whether or not to use the default distance dependent
dielectric constant. If not, he can enter his desired dielectric constant or
use the default value, 40. It should be noted that this entered value is
multiplied by 0.1146 by the program for input to AutoGrid.
Autodpf Commands:
This Module facilitates producing a docking parameter file for AutoDock. The steps in this process are:
It can be chosen from molecules previously added to the moleculeViewer using
the Choose Macromol... option
Selecting the small molecule which has been previously formatted by AutoTors:
It can be picked as a PDB file using the Select PDB Macromolecule
option
It can be picked as a MOL2 file using the Select MOL2 Macromolecule
option
Via Reading a PDBQ-File which adds the ligand to the viewer.
Setting parameters pertaining to the small molecule:
Checking that a grid map exists for each of the ligand atom types
It is important to remember that any of these may be used alone but only GA
and LS may be used together.
Indicating whether a floating grid map exists
Setting the initial translation of the small molecule by:
- choosing the 'random' option which sets a random starting position for the \ligand
Setting the initial quaternion of the small molecule by:
- entering the desired coordinates in the entry
- Choosing the 'random' option which sets a random starting quaternion.
Setting the coefficient of the torsional DOF.
- Entering the desired initial quaternion -Qx,Qy,Qz,Qw in the entry. Qx, Qy,
Qz define the unit vector in the direction of rigid body rotation and Qw the
angle of rotation about this unit vector.
Choosing to set the initial dihedrals for the small molecule or not: If not,
AutoDock assumes that the chi1, chi2, chi3 etc are all zero and does not
change the initial ligand torsion angles. If the user chooses to set the
initial dihedrals, he further chooses:
- for them to be randomly assigned
The user can specify two types of torsion constraints for the ligand:
- an initial relative dihedral angle for each active torsion in the ligand.
- Gaussian constraints which use an inverted Gaussian bell curve to calculate
the energy function input of the constraint. This type of constraint is
specified by two floating point numbers: the perferred angle in the range
-180-+180decreeds and the half-width which is the difference between two
angles at which the energy is half the barrier PLUS an integer which
identifies the torsion according to the list at the top of the AutoTors-
generated input ligand PDBQ file. More than one constraint of this type may be
specified for a single torsion.
If the user specifies torsion constraints, he may also specify the height of
the energy barrier to be applied to these constraints.
- Hard torsion constraints may also be specified. These differ from the
previous type in that the torsion is never allowed to take values bewond the
range defined and in that the second parameter is the full width of the
allowed range of torsion angles.
Moreover, only one constraint of this type is allowed per torsion.
If the user specifies Gaussian torsion constraints, he may also specify
whether to store and output the torsion energies.
The user adjusts these additional parameters:
Saving the results to a file:
- the step sizes of translation, quaternion rotation and dihedral torsion
change.
The user selects which kind of docking parameter file to write :
- energy parameters including energy assigned to atoms outside the grid
volume, the maximum allowable initial energy and the maximum number of
retries.
- output format parameters including the level of detail for the output, the
rms cluster tolerance, the reference file for rms calculations and whether to
do symmetry checking in the rms calculations.
- Simulated Annealing
- GA
- LS
- GALS
AutoStart Commands:
This Module facilitates starting autogrid and autodock jobs and managing them.
Autoanalyze Commands:
This Module facilitates analyzing results of autodock jobs.
These keys are set:
'macroFile' : the Macromolecule file used
After the selected docking log file is parsed, the user can:
'ligand' : the original ligand
'types' : the kinds of grid files used
'runs' : the number of docking runs
'clusterNum' : the number of clusters produced
'clusterList': a list of ADClusters which have members of ADDocked instances.
select a displayed docked conformation using the 'Choose A Docking'
menubutton. This opens a DockingChooser widget which is a ListChooser allowing
selection either in the widget or in the viewer of any of the displayed
docking. Information about each docked conformation is displayed in the
information window of the DockingChooser as different entries are high-lighted
.
display the macromolecule via the "Show Macromolecule" menubutton.
display the original input ligand via the "Show Original Ligand" menubutton.
Both of these menubuttons are linked to file browsers in case the molecule
parsed from the docking log file is not in the current directory.
Finally, the user is able to visualize a grid map using the "Show Grid"
button. This will be linked to an isocontour utility. (currently not
implemented)
| Sophie Coon, February 2001, (sophiec@scripps.edu) |