When creating molecular animations, it’s common to want certain parts of a molecule to stay still while others move—for example, when simulating flexible protein loops or visualizing ligand docking steps. Without a way to hold parts of a structure fixed, animations can easily become confusing or misleading.
This is precisely where the Hold atoms animation effect in SAMSON can help. It allows you to prevent selected atoms from moving during a part of the animation between two keyframes, making your presentations clearer and your molecular stories more compelling.
What does ‘Hold atoms’ do?
The Hold atoms animation fixes the position of selected atoms between two animation keyframes. In other words, from the perspective of the viewer, these atoms will appear stationary while other parts of the system evolve. It’s like saying, “freeze here” to any portion of your model.
Why is this useful?
Keeping parts of a molecule fixed is useful for many reasons:
- 🔬 Emphasize conformational changes that occur only in specific regions.
- 🧱 Simulate ligand binding while keeping a protein backbone static.
- 🎓 Create clear, educational animations by reducing unnecessary motion.
- 📽 Blend multiple effects such as move and hold to tell dynamic molecular stories.
How to add the ‘Hold atoms’ animation
- First, go to the selection tool and select the group of atoms you want to keep fixed.
- Then, open the Animation panel of the Animator.
- Double-click on the “Hold atoms” effect. SAMSON will automatically insert this effect between the current two animation keyframes, if present.
- Adjust the keyframes as needed. You can always move them to alter when atoms begin or stop being held in place.
Visual example
In the example below, atoms are held in place while others move, creating a structured, digestible animation:
Note: While the example above uses a menu that is no longer available in the latest version of SAMSON, all animations are now accessible via the Animation panel in the Animator.
Where to see this in action
Want to see real-world examples? These presentations on SAMSON Connect include the ‘Hold atoms’ animation:
Whether you’re building educational videos, pitching molecular designs, or communicating your findings, a precise animation can make all the difference. Holding key atoms in place gives you control, clarity, and better storytelling potential for your molecular system.
For more details, visit the full documentation page: Hold atoms – SAMSON documentation.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can download SAMSON at https://www.samson-connect.net.