Protein-ligand docking is a crucial step in molecular modeling, unlocking key insights into drug interactions and molecular mechanisms. For many molecular modelers, the setup and optimization of docking workflows can feel labor-intensive and overwhelming. If you’ve been searching for an easy-to-use tool that simplifies this process while maintaining great accuracy, the FITTED Suite SAMSON Extension might be your solution.
The FITTED Suite, developed in partnership with Molecular Forecaster, brings automation and precision to both covalent and non-covalent protein-ligand docking. With SAMSON’s user-friendly interface and the unique features of the FITTED Suite, you can streamline workflows, save time, and focus on deeper analyses. Below, we’ll guide you through a typical non-covalent docking example to show how this tool works.
Step 1: Preparing Your System
First, launch SAMSON and open the target file. For example, in this tutorial, we use the 1E2K structural model, which represents a thymidine kinase protein with the (N)-methanocarba-thymidine ligand. This ligand (referred to as TMC 500) is already bound to the receptor. You can visualize this in SAMSON’s Document View, which organizes the hierarchy of molecules and nodes. This setup ensures no manual pre-preparation—SAMSON’s automated tools take care of water molecules, H-bond optimizations, and other adjustments.
Step 2: Setting Up the Receptor and Binding Site
Define the receptor by selecting the structural model and specifying it in the FITTED Suite. Key parameters such as water molecules and macromolecules (protein in this case) are pre-set, though you can modify them depending on your system’s unique requirements (for example, docking metalloproteins).
Next, define your binding site. Since this tutorial involves self-docking, the binding site can be directly based on the already bound ligand (TMC 500). Simply find and select the ligand in the Document View, and use the From bound ligand option in the binding site section. This step removes the complexity of manually calculating grid centers or binding box dimensions.
Step 3: Preparing the Ligand
Select the TMC 500 ligand and define it in the FITTED Suite under the Set Ligand section. By default, the ligand will undergo automated preparation steps including bond order perception and hydrogen addition. For new ligands, SAMSON’s companion tools like PREPARE and CONVERT further ensure optimized 3D models.
Step 4: Launching Docking
Now, it’s time to specify docking parameters. For non-covalent docking, set the number of runs (e.g., 2) and decide whether to import only the best pose. Once you’ve selected your output folder, click the Dock button. For the tutorial system, the docking takes just a few minutes, and progress is displayed on the interface.
Step 5: Viewing Results and Performing Analysis
After docking is complete, results appear in a table format and as new entries in the Document View. The receptor file will now show added hydrogens and docked ligand poses. Selecting rows in the result table highlights corresponding poses in the 3D viewport, enabling straightforward validation and visualization.
You might want to visualize these results further by adding secondary structure models (ribbons) and licorice visuals for binding residues. SAMSON allows you to customize these visual aids, making it easier to communicate findings to collaborators.
Conclusion
The FITTED Suite streamlines the protein-ligand docking process and integrates seamlessly with SAMSON’s tools for deeper analyses. Whether you’re scripting workflows or visualizing binding interactions, this extension empowers you to achieve reliable results while saving time. Learn more about the FITTED Suite and additional workflows, such as covalent docking, at the official documentation page.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at https://www.samson-connect.net.