Understanding Segment Attributes for Efficient Molecular Modeling

Molecular modelers are often faced with the challenge of efficiently analyzing and manipulating segment attributes in complex models. SAMSON’s Node Specification Language (NSL) provides a powerful way to query and define these attributes, improving workflow efficiency. This post focuses on segment attributes, offering insights into their inheritance, possible values, and practical examples to ease your modeling tasks.

What Are Segment Attributes?

Segment attributes in SAMSON belong to the segment attribute space (short name: s) and apply specifically to segment nodes. These attributes help modelers query and refine molecular structures by targeting specific segments based on shared properties.

Key segment attributes are inherited from the node and structuralGroup attribute spaces. Additionally, a few attributes are unique to segment, offering functionality tailored to segment-level analysis.

Inherited and Specific Segment Attributes

By defining attributes such as visibility, material ownership, or the number of atoms, you can easily manipulate or focus on specific molecular segments. Here are a few highlights:

Inherited Attributes

  • hasMaterial (hm): Use s.hm to check whether a segment has associated material (true or false).
  • name (n): Query segments by their names, e.g., s.n "A" to match segments named “A” or s.n "L*" to match names starting with “L”.
  • numberOfAtoms (nat): Query the total number of atoms in segments with s.nat. For instance, s.nat > 100 identifies segments containing more than 100 atoms.

Segment-Specific Attributes

  • numberOfResidues (nr): Matches segments based on the number of residues they possess, such as s.nr > 130 for segments with more than 130 residues.
  • numberOfStructuralGroups (nsg): Determines the number of structural groups in segments, like s.nsg 10:20 for segments with 10 to 20 structural groups.

Practical Benefits

Incorporating segment attributes into your modeling workflows can save time and reduce manual effort. For instance, leveraging attributes like s.visible or s.selected aids in rendering decisions, while s.nr can streamline residue identification in protein structures.

The ability to combine attributes using logical operators (e.g., and, or, not) further enhances flexibility, allowing you to build complex queries. For example, s.nat > 100 and s.hm identifies segments with more than 100 atoms that include material.

Learn More

For a comprehensive overview of segment attributes and examples of their use, visit the official documentation at https://documentation.samson-connect.net/users/latest/nsl/segment/.

SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON at https://www.samson-connect.net.

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