User:Mary Mendoza/Notebook/CHEM572 Exp. Biological Chemistry II/2013/01/30

Molecular Fingerprinting and Docking of Compounds to the ADA active site

A. Opening Maestro

• From the assigned computer, a new terminal was created from either of the following steps:

1. Finder > Services > New terminal at folder

-or-

2. press the provided shortcut key F5

• Then enter $maestro to open the suite.
• Draw the molecule on the workspace area. Modifications can be made through the Edit panel > build > fragments > atom properties. Sponge the drawn molecule for clarity.
• To save the molecule, create this entry on the project table -or- from the workspace option > project entry > name and create the project and then save.
• The next step is to put the molecule under energy minimization to find a stable energetically conformation.

B. Energy Minimization

• To initiate energy minimization, go to the Applications option > Impact > Minimization.
• Minimization analyzes the molecule using Classical Physics.
• A dialog box appears with the force field set on OPLS 2005.
• Then click the Minimization tab. On the maximum cycles, this was changed to 10,000. The other standard parameters such as gradient criterion (0.01) and energy change criterion (1e-07) were kept. The pH was changed to the desired pH level of 7.4.
• Knowing there are amino acids present, by changing the pH of the parameters, the structure must also be converted to its alkoxide form at pH 7.4. As a result, through atom types O3 was changed to OM.
• After all the parameters were set for minimization, the host zorro was chosen and the minimization was started.
• Double-click the finished minimization on the monitor jobs (from applications option), then label the partial charges of the molecule.
• Save the project entry.

C. Calculation of Fingerprint

• Opened Canvas from the Finder by typing $Canvas
• Created a new project and named it as Aspirin_fingerprint.
• Imported the energy minimized aspirin saved earlier from maestro.
• Under applications option, click binary fingerprints > molprint2D
• Click on the imported molecule and incorporate.
• Export the molecule by saving it with an extension of .fp
• A dialog box will appear, choose remove all properties and click ok.
• Close the project.

D. Screen Fingerprint

• After closing the previous aspirin project, open the zinc database.
• Imported the aspirin.fp molecule and allow duplicate mappings.
• Go to the Applications > similar/distance screen > select aspirin.
  • Tanimoto similarity
• Selected the fingerprint column and choose the fingerprint (aspirin)
• Screened the molecules and then incorporate ~ 15,001
• Clicked the fingerprint screen column and sort in descending order to show molecules closest to aspirin.
• On the panel, select rows 1-15,001
• Saved the selection by exporting the project as aspirin_15001.mae along with its properties and click OK.
• Closed Canvas

E. Docking

• Opened the protein databank (PDB) website, www.rcsb.org, and acquired two ADA Bovine structures. The two following structures were chosen by desirable resolutions:
  • 1KRM (resolution 2.5 angstroms)
  • 2Z7G (resolution 2.52 angstroms)
• The pdb.txt of these structures were downloaded.
• On Maestro, opened the aspirin.prj and imported the downloaded structures of ADA.

Protein Preparation Wizard

• The structures of ADA were protonated according to the pH of 7.4. This was executed from:
  • Workflows > Protein preparation > add H⁺ (see image on the side of the protein preparation wizard dialog box)
  • Uncheck the delete waters on the dialog box and click preprocess.