Protein-ligand interactions are fundamental in drug discovery, but achieving accurate docking results can be challenging due to the complexity of molecular systems. A frequent challenge faced by molecular modelers is streamlining the docking workflow without compromising accuracy, especially when working with flexible macromolecules and diverse ligands. The FITTED Suite Extension in the SAMSON molecular design platform offers an effective solution to this problem, automating protein-ligand docking workflows for both covalent and non-covalent interactions.
In this post, we will guide you through the process of setting up non-covalent docking using the FITTED Suite. Whether you’re designing selective enzyme inhibitors or studying protein-small molecule interactions, this workflow ensures precision and ease of use.
Why FITTED Suite? Faster and Smarter Docking
The FITTED Suite, developed in collaboration with Molecular Forecaster, brings unique strengths to the docking process. It incorporates molecular flexibility, bridging water molecules, covalent functionalities, and even proton shifts for metalloenzymes. Powered by a genetic algorithm, it balances speed and accuracy to provide robust scoring functions. Let’s dive into the non-covalent docking process using the tutorial example protein (1E2K) and its bound ligand, (N)-methanocarba-thymidine (TMC 500).
Step 1: Preparing Your System
Start by opening the 1E2K-A.sam file in SAMSON. This provides the structure of thymidine kinase protein with the ligand TMC 500 bound. No manual system preparation is needed as the FITTED Suite automates tasks like adjusting bond orders, adding hydrogens, generating tautomers, and optimizing H-bond networks. You can, however, verify alternate atom locations and clean up as necessary using Home > Prepare.
Step 2: Defining Key Components
Once the system is open, define the main elements for docking:
- Receptor: Select the
1E2Kprotein model and click Set Receptor. - Binding Site: Choose the From bound ligand option and set the binding site based on the centroid of the already bound
TMC 500ligand. This ensures precise selection for self-docking workflows. - Ligand: Select the
TMC 500ligand and click Set Ligand. Leave the preparation option checked to add hydrogens and perceive bond orders.
The intuitive interface of the FITTED Suite app allows users to set these parameters effortlessly, as shown below:
Step 3: Running the Docking Process
After setting up the system, configure docking parameters in the FITTED Suite. For the tutorial example:
- Set the number of runs to 2.
- Check the option to import only the best docking pose.
- Select Non-covalent as the docking mode.
You can also specify the output folder for results. Once ready, click the Dock button to start the simulation. The intuitive logs and progress bar will keep you informed during the process.
Step 4: Analyzing Results
Once the docking is complete, results are displayed in a table and loaded into the document. You can interact with the generated poses, visualize the receptor-ligand binding, or export the results as a CSV file. Below is an example of the results table:
To visualize the receptor and ligand more clearly, add a secondary structure model via the Visualization menu. You can also apply advanced analyses like ligand-protein interaction mapping using SAMSON’s visualization tools and Extensions.
Final Insights
The FITTED Suite makes non-covalent protein-ligand docking accessible and reliable while minimizing the need for manual interventions. By automating essential steps and providing useful visualization tools, this workflow optimally supports molecular modelers working on diverse systems.
For a detailed step-by-step guide and video tutorial, visit the original documentation page at FITTED Suite Documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at SAMSON Connect.