When working on molecular modeling, filtering, and fine-tuning your selection of molecular structures is a necessity. One important aspect of this is using segment-related attributes effectively. In SAMSON’s Node Specification Language (NSL), you can define and refine your queries by leveraging segment attributes to precisely select parts of your molecular model.
What Are Segment Attributes?
In SAMSON, a segment represents a logical grouping of atoms. Segment attributes are powerful tools for selecting and interrogating these groups based on specific properties. These attributes allow you to evaluate parameters like the number of residues, the presence of a structural group, visibility, or even whether material data is associated with a given segment.
Precise selection means accelerated workflows and better insights, especially when analyzing large datasets or complex molecular models. Let’s dive into the attributes you can use, how they are structured, and practical examples that could save you time in your daily modeling activities.
Understanding the Structure of Segment Attributes
Segment attributes in NSL fall under three main groups:
- Inherited from Nodes: Common attributes such as visibility (
s.v) or material ownership (s.om). - Inherited from Structural Groups: Attributes tied to specific counts, such as numberOfAtoms (
s.nat) and numberOfCarbons (s.nC). - Specific to Segments: Unique attributes like numberOfResidues (
s.nr) and numberOfStructuralGroups (s.nsg).
Each attribute has a short name. For example, visibility is shortened to v, so querying visible segments can be as simple as writing s.v in your NSL queries.
Practical Examples: Segment Attribute Usage
To help you maximize productivity, here are some examples of common queries and their applications:
1. Filtering by Residue Count
This is especially useful for managing and isolating protein or DNA segments:
- To find segments with more than 100 residues:
s.nr > 100. - To narrow down residue ranges, such as between 100 and 120:
s.nr 100:120.
With this level of control, you can focus only on the biologically relevant portions of complex structures.
2. Refining Visibility in Complex Models
If you’re dealing with populated visualizations or renderings, you may want to focus on visible segments:
s.v: Matches segments that are currently visible.not s.v: Matches all invisible segments.
This functionality enhances clarity during presentations or debugging simulations.
3. Filtering Chemical Composition
You can also refine queries based on chemical composition, which is crucial for structural chemists:
- Looking for segments with fewer than 10 carbons:
s.nC < 10. - Targeting segments with specific sulfur ranges:
s.nS 10:20.
Resources to Explore Further
The versatility of NSL’s segment attributes helps streamline complex molecular modeling operations. For detailed reference on specific attributes and additional examples, visit the official documentation page for Segment Attributes in SAMSON.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. You can get SAMSON from SAMSON Connect.