For molecular modelers, working with complex molecular structures often requires precise filtering and selection criteria to streamline workflows. This is where backbone attributes in the Node Specification Language (NSL) within the SAMSON platform can help. These attributes provide a systematic way to specify and manipulate molecular backbones. Let’s explore what backbone attributes offer and how they can make your modeling process more efficient.
What Are Backbone Attributes?
Backbone attributes are defined in the backbone attribute space (short name: s) within NSL. These attributes are specialized for backbone nodes, allowing users to apply specific characteristics and filters to selected molecular backbones.
These attributes can be creatively leveraged for tasks such as highlighting groups of atoms, assessing visibility, specifying material properties, or analyzing atomic compositions in backbones. They are organized into two inheritance categories:
- Attributes inherited from the node attribute space.
- Attributes inherited from the structuralGroup attribute space.
Useful Examples
Let’s go over some practical examples to show how these attributes can be applied to real scenarios:
1. Visibility and Selection
The visible attribute (v) and its related visibilityFlag (vf) allow you to check and manipulate the visibility of backbones. This can be incredibly helpful in decluttering your workspace when managing large biomolecules. For example:
- To select visible backbones:
bb.v - To hide them:
not bb.v
Alternatively, you can use the selected attribute to work with currently selected backbones. For example:
- To filter by selected backbones:
bb.selected
2. Material Properties
The hasMaterial (hm) and ownsMaterial (om) attributes allow you to detect if a backbone has—or owns—material. Examples include:
- Orchestrating queries such as
bb.hm(backbones with material). - Or
not bb.hm(backbones without material).
These are particularly useful for tasks such as analyzing material presence in molecular assemblies.
3. Analyzing Atomic Composition
Inherited from the structuralGroup attribute space, several attributes allow for quantifying the composition of atoms in backbones. For instance:
- Specify backbones containing more than 10 carbons:
bb.nC > 10. - Target backbones with a specific range of hydrogens:
bb.nH 10:20.
Such atomic analysis can aid in highlighting specific structural features or filtering based on molecular constraints.
Advanced Searches with Backbone Attributes
The name attribute (n) is a particularly powerful filtering tool for assigning or identifying specific backbones based on string matching. For example:
- To isolate backbones named “A”:
bb.n "A". - To use partial string matching with a wildcard:
bb.n "L*".
This flexibility in naming can make it significantly easier to manage molecular entities in intricate models.
Conclusion
By utilizing backbone attributes in NSL, molecular modelers can simplify their workflows, improve search precision, and better organize their molecular data. These attributes open up powerful filtering and customization options to fine-tune your modeling approach. To dive deeper and explore a comprehensive list of backbone attributes, visit the official documentation page.
SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON at samson-connect.net.