Mastering Backbone Filters for Molecular Modeling

When working in molecular modeling, sorting and filtering data efficiently can be a game-changer. Whether you’re visualizing complex molecular backbones or performing targeted investigations, having a nuanced control over backbone attributes can simplify your workflow. Fortunately, SAMSON’s Node Specification Language (NSL) offers a powerful way to query and filter backbone attributes effectively.

What are Backbone Attributes?

The backbone attribute space in NSL is designed specifically to describe and query properties of backbone nodes. It provides a set of attributes, such as visibility, material ownership, atomic composition, charges, and more, that help molecular modelers refine their selections dynamically.

Attributes are easily referenced with both full names (e.g., numberOfCarbons) and short names (e.g., nC), making them flexible and convenient. For example, if you’re targeting visible backbones, you can use bb.v, where v stands for visible.

Key Features of the Backbone Attribute Space

Here are some of the most commonly used attributes in the backbone attribute space:

Atomic Composition: You can query the number of specific atoms, such as carbon (bb.nC), hydrogen (bb.nH), oxygen (bb.nO), and more. For example, use bb.nC < 10 to find backbones with fewer than 10 carbon atoms or bb.nO 10:20 to select backbones containing 10 to 20 oxygen atoms.
Visibility: The visible (v) and hidden (h) attributes help you filter backbones based on their visibility state. For instance, not bb.v lets you work with hidden backbones.
Material Ownership: Use ownsMaterial (om) and hasMaterial (hm) to check material-specific properties. For example, bb.om returns backbones owning material, while not bb.hm identifies those without associated materials.
Selection: Attributes such as selected and selectionFlag (sf) allow you to focus on previously selected or flagged backbones. For instance, bb.selected retrieves all backbones marked as selected.
Charge Properties: The formalCharge (fc) and partialCharge (pc) attributes help modelers filter backbones by charges. For instance, use bb.pc > 1.5 to locate backbones with partial charges greater than 1.5.

Practical Example

Let’s say you’re working on a molecule where you only want to focus on visible backbones with more than 5 carbon atoms and a formal charge greater than 0.

Here’s how you would write your query using NSL:

bb.v and bb.nC &gt; 5 and bb.fc &gt; 0

1	bb.v and bb.nC > 5 and bb.fc > 0

This query enables targeted exploration and workflow organization, saving you time and helping you stay productive.

Streamlining Molecular Design

By leveraging backbone attributes inherited from node and structuralGroup attribute spaces, molecular modelers can efficiently query both structural details and general configurations using simple yet powerful expressions. The clear syntax offered by NSL ensures that everyone, from novices to seasoned professionals, can take advantage of these filters in SAMSON.

To learn more about how to use backbone attributes in SAMSON’s NSL, explore the official documentation.

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