Molecular modeling often involves navigating complex datasets of molecular structures. One recurring challenge is isolating or identifying specific molecular conformations, like particular paths or chains. Did you know that SAMSON’s Node Specification Language (NSL) provides a highly convenient way to define and query attributes of conformations using path attributes? In this blog post, we’ll break down how you can efficiently leverage these attributes to streamline your modeling workflows.
What Are Path Attributes?
Path attributes in SAMSON are part of the path attribute space (short name: p). They work exclusively with conformation nodes, allowing users to specify properties of molecular paths in their structural models. This means you can filter conformations based on their names, selection status, or even the number of atoms present in the path.
Inherited Attributes You Can Use
Some of the most commonly used attributes for paths aren’t unique to the path attribute space but are inherited from the general node space. Here are the key ones:
- Name (short name:
n): You can match paths by their names using string values. For instance:p.n "A": matches paths named “A”.p.n "L*": matches paths with names starting with “L”.
- Selected: Indicates whether a path is selected. You can use it as a filter:
p.selected: matches selected paths.not p.selected: matches paths that are not selected.
- SelectionFlag (short name:
sf): Another boolean attribute to query selection state. For example:p.sf: matches paths with the selection flag enabled.p.sf false: matches paths with the selection flag disabled.
An Attribute Unique to Paths: Number of Atoms
Molecular modelers often need to work with the size of paths, and the numberOfAtoms attribute (short name: nat) is tailor-made for this purpose. It allows you to filter paths by their atom count. For example:
p.nat > 100: matches paths with more than 100 atoms.p.nat 100:200: matches paths with 100 to 200 atoms.
This is particularly handy for analyzing large complexes or isolating specific regions of a structure.
Putting It All Together
Using these attributes, you can craft powerful NSL queries to zoom into specific conformations in your models effortlessly. For instance, suppose you’re working on a large protein and need to isolate paths named “HelixA” with a selection flag enabled and atom count between 50 and 150. You could write the query:
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p.n "HelixA" and p.sf and p.nat 50:150 |
Such a query enables precision, saving you valuable time during modeling and analysis.
To explore all the details about path attributes and more examples, check out the full documentation at this link.
Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get started today and accelerate your molecular modeling workflows!