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Prointeract · Contacts Analysis

See the Residue Contacts Behind Molecular Interfaces

Identify spatially close residue pairs in a protein structure, characterize their contact types and generate structured interaction data.

Close-up of the interface between a nanobody (navy) and green fluorescent protein (gold): interface residues as ball-and-stick, backbones as soft tubes, and three polar contacts labelled with their distances in angstroms

A real interface: PDB 3OGO, a nanobody on green fluorescent protein, with three polar contacts and their distances computed from the coordinates. Proximity, not proven hydrogen bonds, and an example of the output rather than a project result.

What it is

A bioinformatics platform for analyzing and visualizing inter-chain and intra-chain interactions in proteins and antibodies — identifying and characterizing hydrogen bonds, hydrophobic and electrostatic interactions and other structural contacts.

Supporting work on protein stability, structural organization and binding mechanisms in antibody engineering, protein design and drug discovery.

  1. A · Structure input

    Single file or a batch

    Analyse one structure, or switch to multiple files to run several structures, or a whole folder, in one go.

    • Single-structure analysis
    • Batch analysis of many files
    Single file or a batch
  2. A · Structure input

    Attach a structure

    Attach a PDB or mmCIF structure file, or type a server path.

    • PDB, ENT, CIF and mmCIF files
    Attach a structure
  3. B · Contact settings

    Interchain or intrachain

    Look for contacts between different chains, such as an antibody and its antigen, or within a single chain.

    • Interchain (between chains)
    • Intrachain (within a chain)
    Interchain or intrachain
  4. B · Contact settings

    Set the distance cutoff

    Atom pairs within the cutoff are considered. The default is 5.0 Å.

    • Default cutoff 5.0 Å
    • Adjustable per run
    Set the distance cutoff
  5. B · Contact settings

    Keep antigen contacts only

    Optionally exclude heavy–light contacts to keep the antigen contacts. This applies to interchain analysis.

    • Optional filter
    • Interchain mode only
    Keep antigen contacts only
  6. B · Contact settings

    Run many structures together

    In batch mode, select several files or a folder. Each structure is analysed with the same settings.

    • Select files or a whole folder
    • Same settings for every structure
    Run many structures together
D · Next step

From a structure to residue-level contacts

The analysis returns residue-pair contact tables with minimum distances, contact-type labels and CSV export. Labels are geometric assessments, not binding energies or confirmed hydrogen bonds. Try the example below to see how atom contacts roll up into residue pairs.

Run it

Analyze a structure

The analysis itself runs in the Prointeract application, not on this page. You provide a PDB, ENT, CIF or mmCIF file (or a batch), choose interchain or intrachain, optionally change the 5.0 Å cutoff, and receive a summary and CSV output.