The primary input for LigPlot is a standard PDB (Protein Data Bank) file containing the 3D coordinates of the protein and the bound ligand.
When comparing wild-type and mutant proteins, LigPlot can visually demonstrate how a mutation (e.g., changing a Threonine to an Alanine) might remove a critical hydrogen bond, explaining a loss in binding affinity or catalytic activity. ligplot
Medicinal chemists use LigPlot diagrams to identify "hot spots" in a binding pocket. By visualizing which residues form specific hydrogen bonds, chemists can modify functional groups on a lead compound to enhance affinity (e.g., adding a hydroxyl group to target an unsatisfied hydrogen bond donor). The primary input for LigPlot is a standard
Hydrophobic interactions are identified by calculating the proximity of non-polar atoms (carbon atoms in aromatic rings or aliphatic chains) of the ligand to non-polar atoms of the protein side chains. By visualizing which residues form specific hydrogen bonds,
Figure 1 (conceptual): A LIGPLOT of the HIV-1 protease inhibitor indinavir. Hydrogen bonds are green dashed lines; hydrophobic contacts are red arcs; the ligand is in thick black bonds.
LigPlot represents a critical intersection between computational geometry and visual communication in biology. By translating complex 3D coordinate data into standardized 2D interaction maps, it democratizes access to structural insights, allowing chemists and biologists to intuitively grasp the mechanics of molecular recognition. While newer tools with 3D-hybrid views exist, the clarity and simplicity of the LigPlot schematic ensure its continued relevance as a staple tool in the structural biologist's arsenal.
(and its successor LigPlot+ ) is a software suite used to generate schematic 2D representations of 3D protein-ligand and protein-protein complexes. It facilitates drug discovery and structural biology by clearly visualizing the intermolecular forces that stabilize these complexes. Core Visualization Features