Understanding Molecule Attributes in SAMSON: A Guide for Molecular Modelers

For molecular modelers, quickly identifying and manipulating molecular properties is essential. The integrative molecular design platform SAMSON offers a powerful way to address this challenge through the use of molecular attributes, accessible via the Node Specification Language (NSL). In this post, we’ll explore the key molecule attributes available in SAMSON and how they can simplify molecular modeling tasks.

What Are Molecule Attributes?

Molecule attributes are properties or traits specific to molecular nodes in SAMSON. By leveraging NSL, modelers can filter, classify, and manipulate molecules based on these attributes. This functionality is particularly useful for tasks such as filtering molecules by size, visualizing charged residues, or identifying structural groups efficiently without resorting to manual inspection. Let’s dive into some of these key attributes.

Key Attributes at a Glance

The molecule attribute space (short name: mol) provides access to various attributes. Below, we summarize the three types of molecule attributes and their utility:

Inherited from the Node Attribute Space: Attributes like hasMaterial (hm, e.g., mol.hm), hidden (h, e.g., mol.h), and name (n, e.g., mol.n "A") help manage visibility, categorization, and metadata for nodes.
Inherited from the Structural Group Attribute Space: Attributes such as numberOfAtoms (nat, e.g., mol.nat < 1000), numberOfCarbons (nC), and formalCharge (fc, e.g., mol.fc > 1) allow detailed control over the structural characteristics of molecules.
Specific to Molecules: Unique attributes like numberOfChains (mol.nc), numberOfResidues (mol.nr), and numberOfSegments (mol.ns) let you explore molecules at a higher level of granularity.

Practical Applications

Here are some practical examples of common tasks you can accomplish using molecule attributes in SAMSON:

1. Identifying Large Molecules

If you’re working with a dataset of molecules and want to identify larger structures, the numberOfAtoms parameter can be your go-to. For instance, to filter molecules with fewer than 1000 atoms, use:

mol.nat &lt; 1000

1	mol.nat < 1000

2. Classifying Proteins by Chains

For protein modeling, the numberOfChains attribute helps you classify molecules based on their chain count. To find molecules with fewer than three chains, write:

mol.nc &lt; 3

1	mol.nc < 3

Alternatively, for molecules with 2 to 4 chains:

mol.nc 2:4

1	mol.nc 2:4

3. Analyzing Residues

Residue count plays a significant role in understanding molecule complexity. Use the numberOfResidues attribute to identify molecules exceeding 100 residues:

mol.nr &gt; 100

1	mol.nr > 100

Or select molecules within the range of 100 to 120 residues:

mol.nr 100:120

1	mol.nr 100:120

Streamlining Your Workflow

The true power of SAMSON’s molecule attributes lies in their ability to combine attributes into logical statements to customize your workflow. For example, you can search for visible molecules (mol.v) with a formal charge greater than 1 (mol.fc > 1) in just a few lines of code. Additionally, structural biologists can quickly isolate proteins with specific residue counts or specific chain thresholds.

Pro Tip: Make use of the short names (hm, n, nc, etc.) for faster queries and compact expressions.

Wrapping Up

SAMSON’s molecule attributes allow molecular modelers to efficiently explore and categorize complex structures without manual effort. By leveraging the Node Specification Language’s attribute space, modelers save time, reduce errors, and enable greater focus on their scientific goals.

To learn more about molecule attributes and NSL, visit the official documentation.

Note: SAMSON and all SAMSON Extensions are free for non-commercial use. Get SAMSON here.