For molecular modelers, setting up ligands for simulations can often be a tedious and error-prone step. SAMSON’s Ligand Path Finder app simplifies this process with an intuitive workflow that ensures precision while setting up your system for ligand unbinding pathway exploration. In this post, let’s walk through how to properly define and set up ligands and atoms using the Ligand Path Finder app.
Why Is Setting Up Ligands Crucial?
Accurately defining ligand atoms, active atoms, and fixed atoms is critical when modeling molecular dynamics or ligand unbinding pathways. A well-prepared setup ensures reliable simulation results and reduces computation overhead. Moreover, with tools like SAMSON, you can facilitate the definition of these parameters efficiently without manual guesswork.
Step 1: Define the Ligand Atoms
In the Document view, select your ligand. In the case of this tutorial, the ligand is TDG. By selecting TDG, all atoms belonging to the ligand will be highlighted, as shown below:
Once the ligand is selected, click the Set button in the Ligand Path Finder app to confirm the ligand atoms. After this step, the rest of the system will automatically be categorized as protein atoms.
Step 2: Choose Active Ligand Atoms
Among the ligand atoms, select the “active” atoms that will serve as controllers for influencing ligand motion during simulations. For example, in the tutorial system, the active ligand atom is the sulfur atom (S1) from TDG. A pre-configured group in the document simplifies this step. Double-click on the group, or manually select the sulfur atom in the Document view:
Next, click the Add button in the Ligand Path Finder app to include this atom in the active group. The app confirms this selection in the Advanced Information box.
Step 3: Assign Fixed Protein Atoms
To prevent the protein from drifting during simulations, assign certain protein atoms as “fixed”. The tutorial suggests selecting the CA atom of residue HIS 205. Like before, a pre-defined group simplifies selection. Double-click the corresponding group or manually locate the atom:
Add this atom to the fixed group by clicking the Add button. The app shows the total number of active and fixed atoms selected in the Advanced Information box for quick verification.
Review Your Selections
You can confirm the setup at any time by using the Select buttons associated with ligand atoms, active atoms, or fixed atoms. The selections will be shown visually. If needed, reset specific groups by clicking the Reset button (
) to start over.
Conclusion
Following this streamlined setup process ensures that your ligand atoms and system configuration are correctly defined for efficient and accurate pathway exploration. By reducing the margin for error and including intuitive tools for adjustments, SAMSON makes it easier to set up molecular systems for simulations.
To dive deeper into this process or explore related features, check out the full Ligand Path Finder documentation.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get started today by downloading SAMSON from SAMSON Connect.