Case Study
AI PROTAC Ternary Complex Modeling Service

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AI PROTAC Ternary Complex Modeling Service - CD ComputaBio
AI-enabled ternary complex analysis

AI PROTAC Ternary Complex Modeling Service

Move beyond binary affinity. We build and compare protein–PROTAC–E3 ensembles to identify geometries that are stable, cooperative, linker-feasible, and positioned for productive ubiquitination.

Linker-aware pose generationAI ensemble rankingMD stability analysisLysine accessibility
Service coverage

Model the complex that determines whether binding becomes degradation

TC

Reduce pose uncertainty

Generate ternary-complex ensembles from experimentally solved or modeled protein structures, with restraints that respect both warhead and recruiter binding modes.

  • Protein–protein orientation sampling
  • Linker conformer generation
  • Clash and geometry filtering
AI

Prioritize plausible assemblies

Combine structural descriptors and physics-aware scores to rank poses by interface complementarity, linker strain, contact persistence, and ensemble support.

  • Feature-based pose ranking
  • Cluster consensus analysis
  • Confidence-aware shortlisting
MD

Test dynamic stability

Challenge shortlisted geometries with molecular dynamics instead of relying on one static snapshot.

  • Replicate MD simulations
  • Interface and contact persistence
  • Conformational state analysis
α

Interpret cooperativity drivers

Compare binary and ternary energetic contributions to identify protein–protein contacts that may stabilize—or penalize—the recruited state.

  • Interface energy decomposition
  • Hotspot and frustration mapping
  • Cooperativity hypotheses
Ub

Assess ubiquitination geometry

Evaluate exposed target lysines in the context of modeled ligase assemblies so that pose ranking reflects downstream degradation feasibility.

  • Lysine accessibility mapping
  • E2-to-lysine distance analysis
  • Productive-pose classification
Rx

Choose the next degrader designs

Translate model evidence into linker, attachment-point, and candidate recommendations that your chemistry and biology teams can test.

  • Candidate ranking matrix
  • Design-change rationale
  • Validation experiment plan

A focused answer to a specific degrader decision

Projects can begin with one PROTAC, a linker series, competing E3 recruiters, or an unexplained degradation SAR. The analysis depth is scaled to the decision—not forced into a universal pipeline.

  • 1Which ternary orientations remain feasible across linker conformers?
  • 2Which designs stabilize new protein–protein contacts without excessive linker strain?
  • 3Which poses expose target lysines to a realistic ubiquitin-transfer geometry?
  • 4What should be synthesized or measured next to resolve model uncertainty?
Image placeholderRecommended asset: publication-quality molecular rendering of a target–PROTAC–E3 ensemble with several semi-transparent alternative poses.
Modeling strategy

From structural inputs to a decision-ready ternary ensemble

The workflow preserves conformational diversity early, then spends simulation effort only where it can change candidate selection.

Request a Modeling Scope
  1. Anchor the two binding events

    Review POI and E3 structures, binding-site confidence, ligand poses, attachment vectors, missing regions, protonation states, and any experimental restraints.

    Structure auditBinding-pose QCAttachment vectors
  2. Assemble linker-feasible orientations

    Sample protein–protein approaches together with PROTAC conformers, rejecting assemblies that cannot satisfy bond geometry or introduce severe steric conflict.

    Conformer ensemblesRestrained dockingGeometry filters
  3. Rank the ensemble with AI and physics

    Cluster poses and integrate interface area, contact quality, linker strain, energetic terms, and recurrence across independent sampling runs.

    Pose clusteringFeature scoringUncertainty ranking
  4. Stress-test shortlisted complexes

    Run replicate molecular dynamics, examine interface persistence and conformational transitions, and compare ternary behavior against relevant controls.

    Replicate MDMM/GBSAState analysis
  5. Connect geometry to degradation feasibility

    Map solvent-exposed lysines, assess productive ligase orientation, and deliver a ranked design matrix with proposed validation experiments.

    Lysine mappingUbiquitination geometryDesign memo
AI with mechanistic guardrails

Ranking is useful only when its assumptions stay visible

AI-assisted scoring can compress a large pose space, but ternary-complex data remain sparse and system dependent. We therefore report the evidence behind every rank and keep physics-based checks, ensemble agreement, and applicability limits in the same decision table.

GeometryAttachment vectors, clashes, linker strain
InterfaceBuried area, contacts, electrostatics
DynamicsPose survival and contact persistence
FunctionLysine access and ligase orientation
Candidate prioritization

A ranked matrix—not a single “best” pose

Representative output groups designs by confidence and decision value, separating structurally supported candidates from informative experiments that can test competing hypotheses.

AStable interface + feasible linker + productive lysine geometry
BStrong ternary geometry with one unresolved structural assumption
CMechanistically informative control or linker-boundary design
DPersistent clash, strained linker, or unproductive ligase orientation
Decision-ready deliverables

Outputs your chemistry and biology teams can act on

Structure package

Ternary ensemble files

Ranked 3D complexes, representative clusters, prepared structures, and clear file annotations.

Evidence package

Pose comparison report

Linker geometry, interface contacts, energetic terms, stability descriptors, and confidence notes.

Mechanism package

Ubiquitination feasibility map

Accessible lysines, geometry-based productivity assessment, and competing mechanistic hypotheses.

Action package

Design and assay recommendations

Candidate tiers, linker or attachment-point changes, controls, and the most informative next experiments.

Published data

What peer-reviewed studies teach us about modeling productive ternary complexes

Study [1] · Dynamic rescoring

Three-body energetics and protein–protein contacts improve PROTAC pose evaluation

Li W, Zhang J, Guo L, Wang Q. Journal of Chemical Information and Modeling. 2022;62(3):523–532.

The authors used molecular dynamics and MM/GBSA to address the three-body nature of PROTAC complexes. In BRD4 BD2 systems, the calculated binding energies correlated with experimental affinity data, and the protocol improved reranking of poses generated by an earlier docking workflow.

Service implication: static docking is treated as hypothesis generation. Shortlisted poses are challenged dynamically and evaluated with the induced protein–protein interface included.
Method → evidence → decisionOriginal schematic
Pose ensembleGenerate candidate ternary orientations from binary complexes and PROTAC geometry.
MD + MM/GBSASample three-body dynamics and estimate energetic support including protein–protein contacts.
Reranked posesAdvance assemblies with sustained geometry and better agreement with experimental trends.
Dynamic stabilityInterface contributionCooperativity contextPose discrimination
Study [2] · Predictive structural framework

Ternary affinity and cooperativity connect structural interfaces with degradation behavior

Wurz RP, Rui H, Dellamaggiore K, et al. Nature Communications. 2023;14:4177.

Across VHL-recruiting degraders for SMARCA2 and BRD4, ternary-complex affinity and cooperativity correlated with degradation potency and initial degradation rates. The study also used a structural modeling workflow in which total buried interface area agreed with measured ternary binding affinity.

Service implication: candidate ranking integrates structural interface descriptors with experimental ternary-complex measurements whenever available, rather than treating molecular geometry as an isolated endpoint.
Architecture → interface → degradationOriginal schematic
PROTAC variantsVary warhead, linker, recruiter, and attachment geometry across a matched series.
Ternary attributesMeasure affinity and cooperativity; model interface organization and buried surface area.
Design frameworkRelate structural and biophysical evidence to degradation potency and rate.
Ternary affinityCooperativityBuried interfaceDegradation kinetics

References

  1. Li W, Zhang J, Guo L, Wang Q. Importance of Three-Body Problems and Protein-Protein Interactions in Proteolysis-Targeting Chimera Modeling: Insights from Molecular Dynamics Simulations. J Chem Inf Model. 2022;62(3):523–532. https://doi.org/10.1021/acs.jcim.1c01150
  2. Wurz RP, Rui H, Dellamaggiore K, et al. Affinity and cooperativity modulate ternary complex formation to drive targeted protein degradation. Nat Commun. 2023;14:4177. https://doi.org/10.1038/s41467-023-39904-5
Project questions

Frequently asked questions

A strong modeling project begins by defining which uncertainty must be reduced and what experimental decision follows.

Preferred inputs are structures or reliable models of the protein of interest and E3 ligase, bound poses or chemical structures for both ligands, linker chemistry, attachment atoms, and any known ternary or degradation data. When a structure is missing, we can first assess whether homology modeling or structure prediction is suitable; that additional uncertainty is recorded explicitly.

Yes. Comparative projects can hold the target warhead constant while testing recruiters, attachment vectors, or linker families. The scope should be designed so that sampling depth remains sufficient for each branch and conclusions are not driven by unequal simulation effort.

No. Ternary-complex formation is necessary but not sufficient. Cellular permeability, target and ligase abundance, ubiquitin-transfer geometry, degradation kinetics, proteasome engagement, and compound exposure can all affect outcome. We position modeling as a prioritization and mechanism tool, not a guarantee of cellular degradation.

AI-assisted scores help rank and cluster large pose ensembles. They are interpreted together with linker feasibility, explicit structural checks, molecular dynamics, uncertainty across independent runs, and experimental data. Final reports distinguish model-supported conclusions from testable hypotheses.

Depending on the decision, useful follow-up data may include ternary binding or cooperativity measurements, target engagement, degradation concentration–response and time-course assays, hook-effect characterization, ubiquitination assays, mutagenesis of proposed interface or lysine sites, and structural studies.

Start a project

Bring your ternary-complex question into focus

Share the target, E3 ligase, degrader structures, and the decision your team needs to make. CD ComputaBio will propose a fit-for-purpose modeling scope and identify the minimum additional inputs needed.

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