How they fit together

Most work starts by converting a PDB entry into typed MOL2 files, then follows one of two paths: encode the interactions of a known complex, or go looking for a pocket in the first place.

pdbconv VolSite IFP INTS GRIM Realign

IFP is binding-site dependent, so its fingerprints compare poses within one site. INTS drops that constraint by storing interactions as pseudoatoms, which is what lets GRIM compare complexes that share nothing at all.

Realign

Align proteins, cavities or ligands. Computes the transformation that superposes one molecule onto another and applies it to as many other files as you like — the step that turns a GRIM match into a structure you can look at.

Matches by atom order, MOL2 type, atom name or Cα. Writes rot_*.mol2.
Tutorial
IFP

Converts the 3D structure of a protein (or nucleic acid) – ligand complex into a residue-based interaction fingerprint, and computes pairwise similarities between fingerprints. The standard way to rank docking poses on the interactions they reproduce.

11 bits per binding-site residue, or 7 in legacy mode. Tanimoto scoring built in.
Tutorial
INTS

Lists in a table the non-covalent interactions of a 3D structure — hydrophobic, aromatic, hydrogen bonds, ionic bonds, halogen bonds and more — and encodes each as a pseudoatom, giving a representation that no longer depends on the binding site.

Pseudoatoms placed on the protein, the ligand, between them, or all three. Optional triplet fingerprints.
Tutorial
GRIM

Converts complexes into generic 3D graphs and computes pairwise similarities by finding their largest common subgraph. Detects that two unrelated proteins bind their ligands the same way, and returns the alignment that proves it.

Clique detection over interaction graphs. Also screens a full pose file against a reference binding mode.
Tutorial
VolSite

Detects cavities at the surface of a protein and estimates their druggability, with or without a bound ligand to point at. Can also emit the cavity as a pharmacophore ready to screen with.

Pharmacophore-annotated grid points, five buriedness cut-offs, druggability score. Exports .chm, .pml, .mol2.
Tutorial
Utils

Various goodies: computes buried surface areas, and fragments a protein-bound ligand according to RECAP rules while keeping its protein context.

Subcommands bsa and frag.
Tutorial

Companion tools

Three more commands ship in the same executable and support the modules above: pdbconv converts PDB entries into typed MOL2 files and is the usual entry point, sims compares fingerprints with a choice of six metrics, and AtomProps reports how every atom was typed — the first place to look when an expected interaction fails to show up.