Aligning protein sequences and structures is critical for molecular modelers aiming to understand functional similarities, evolutionary relationships, or to design novel molecules. However, the process can be time-consuming, especially when working with multiple chains or complex models. Fortunately, SAMSON’s Protein Aligner extension streamlines this process into an efficient workflow.
Why Does Protein Alignment Matter?
Protein alignment is more than just a comparison of sequences or structures. It reveals conserved residues, which often hold functional significance (like ligand-binding sites), helps compare conformations across species or mutants, and aids in building accurate homology models. These insights drive meaningful downstream analyses in molecular design workflows.
Simplify Alignment in SAMSON
The Protein Aligner extension in SAMSON provides flexible tools to align sequences by structure or chains, as well as perform region-specific alignments. Here’s how to get started:
Sequence Alignment in Action
Once your proteins are loaded into SAMSON (for example, hemoglobins 1DLW and 1RTX), open the Protein Aligner via Home > Align. The tool provides two modes for sequence alignment:
- Align sequences (by structure): Aligns one model to another based on their structural models.
- Align sequences (by chain): Aligns individual chains, which is particularly useful for oligomeric structures.
Click a corresponding Align sequences button to generate an alignment. Highlight conserved amino acids to understand key similarities. For example, you can toggle the display of amino acid properties (e.g., similarity or polarity) using the Highlight residues feature:
As shown above, the conserved residues across two protein sequences can be clearly identified, enabling modelers to interpret whether functional regions remain unchanged.
Note
If a residue matches multiple selected properties, its color blends the corresponding shades, making it easier to detect overlaps in residue properties.
Region-Specific Alignment
For cases where only specific parts of proteins are of interest, SAMSON allows region-specific alignment. For instance, if two alpha-helices appear similar but are not perfectly superimposed, select the residues corresponding to those helices in the sequence view. This enables precise alignment of only those regions. Here’s an example:
Once regions are selected, click the alignment button (next to the RMSD value) to superimpose just those residues. The results will display improved local alignment:
Next Steps
After alignment, you can export your results for use in homology modeling or molecular design projects. For instance, conserved residues identified in a sequence could be mapped onto ligand-binding sites or used to refine docking workflows. The extensibility of SAMSON also makes it easy to repeat alignments with related proteins or additional chains.
Get Started Today
If you’re tired of wrestling with misaligned sequences or structurally mismatched proteins, the Protein Aligner in SAMSON offers a streamlined solution for both beginners and seasoned molecular modelers. Visit the detailed documentation at SAMSON Protein Aligner Documentation to learn more and dive deeper into all its capabilities.
SAMSON and all SAMSON Extensions are free for non-commercial use. Download SAMSON today at SAMSON Connect.