Molecular modeling often involves managing complex structures, and molecular modelers frequently encounter challenges when identifying and categorizing specific chains within their models. This is especially true when working with large biomolecular systems. To alleviate this pain, SAMSON’s Node Specification Language (NSL) introduces chain attributes: a powerful system to assist molecular modelers in filtering, querying, and working with chain-level details efficiently.
What Are Chain Attributes?
Chain attributes in NSL provide a categorized space (known as the chain attribute space, or c) for working specifically with chain nodes in molecular models. This space includes both generic attributes inherited from broader categories like the node or structuralGroup attribute spaces, and attributes unique to the chain level.
These attributes allow you to query and manipulate chains based on detailed properties, ranging from visibility and material ownership to residue counts and atomic compositions.
Simplifying Your Molecular Workflow
Let’s explore how chain attributes can make your workflow more intuitive and help you focus on what matters:
1. Selection Attributes: Easily determine or filter chains based on selection and visibility properties. For instance, you can determine if a chain is visible (c.v) or hidden (c.h). This helps in rendering and visualization tasks.
2. Composition Analysis: Chain attributes simplify the analysis of molecular composition. For example, you can query the number of atoms, hydrogens, or sulfurs in a specific chain using the attributes c.nat, c.nH, or c.nS.
3. Chain IDs and Residues: Specify and query chains based on a chain ID (c.id) or select chains with a given range of residues (c.nr). This makes it easier to categorize chains in complex systems, such as proteins or polymers.
Examples: Practical Chain Queries
The following examples exemplify how you can directly apply chain attributes in NSL for precision filtering:
c.id 2:4: Matches chains with chain IDs between 2 and 4.c.nr > 100: Matches chains with more than 100 residues.c.nat < 300: Matches chains with fewer than 300 atoms.c.vf false: Matches chains that are explicitly flagged as invisible.
Even intricate queries combining these attributes become manageable, saving you significant time and effort.
A Closer Look at the Attribute Table
The documentation breaks down the available attributes into inherited and specific ones, providing clarity over how each attribute can be used. Here’s an example table snippet for reference:
| Attribute Name | Short Name | Possible Values | Examples |
|---|---|---|---|
| chainID | id |
integers | c.id 1c.id <= 3 |
| numberOfResidues | nr |
integers | c.nr 100:120 |
For a full breakdown of all available attributes, refer to the SAMSON documentation.
Conclusion
Chain attributes within SAMSON’s NSL empower modelers by simplifying chain-specific queries and operations. Whether you’re refining visualization workflows or performing chain-level structural analysis, this toolkit provides the precision and ease of use you need.
To dive deeper into the details, visit the full documentation page here.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can start using SAMSON today by visiting SAMSON Connect.