2019 DOCK tutorial 1 with PDBID 2BXF

This tutorial contains a step by step approach to dock a known ligand to a known receptor.

I. Introduction

DOCK

DOCK is a molecular docking software that was originally developed at UCSF by Dr. Irwin Kuntz, Dr. Brian Shoicket, and colleagues. DOCK is used in drug discovery and molecular modeling. It consists of 2 main components: a search algorithm to explore chemical space for conformations and a scoring function to rank the results.

2BXF

The tutorial will be based on the PDB file 2BXF downloaded from the PDB Database. 2BXF is the crystal structure for human serum albumin complexed with diazepam.

Organization of Directories

We set up the files in our project space as such. It will be helpful to have these folders ready ahead of time.

             0.files
             1.dockprep
             2.surface_spheres
             3.gridbox
             4.dock
             6.footprint
             7.virtual_screen
             8.virtual_screen_mpi
             9.cartesianmin
             10.rescore

II. Preparation of the ligand and receptor

Download the pdb file 2BXF from Protein Data Bank and save the file in the 0.files folder.

Checking the structure

- Open Chimera, open the downloaded pdb file, and check the structure for missing residues, gaps, heme groups, missing loops, and size. We recommend using proteins with no heme groups and proteins of a relatively smaller size. 2BXF did not have any of the preceding potential problems. 

Preparation of receptor

 - Open 2BXF.pdb through Chimera
 - Isolate the receptor by deleting the ligand. Click on the ligand and delete it (Actions -> Atoms/Bonds -> Delete). 
 - Save the isolated receptor as a mol2 file (File -> Save mol2 -> 2BXF_rec_noH_mol2)

This receptor has been prepared without Hydrogens (hence the noH)

- Open 2BXF_rec_noH.mol2 file again using Chimera and use the following instructions to prepare the receptor file to be used in DOCK.
          Tools -> Structure Editing -> Add H (To add Hydrogen atoms)
          Tools -> Structure Editing -> Add Charge (To add the charge use the latest AMBER force filed available for standard residues. Here we used AMBER ff14SB)
          Save as a mol2 file. (2nnq_rec_withH.mol2)

 - If you follow the step below all the above stated steps will automatically appear one after the other to prepare the receptor. 
          Tools -> Structure/Binding Analysis -> DockPrep

Preparation of ligand

 - Open the PDB file via Chimera.
 - Using Chimera, isolate the ligand, add H atoms, add charge and save it as a mol2 file by following the same steps followed for the receptor.

Once all the files are prepared make sure to save the files in 1.dockprep folder.