AlphaFold-era protein modeling · Validation · Refinement for downstream

Protein Modeling Service

AlphaFold2 and open-source alternatives have commoditized single-chain prediction. But a raw model is not a decision-ready structure. We answer the real question: Is this model reliable for docking, MD, or drug design? Our protein modeling service focuses on model quality assessment, refinement of hard targets (GPCRs, membrane proteins, loops, non-natural modifications), and integration into structure-based discovery workflows — so you don't waste cycles on a misleading fold.

AlphaFold2 validation & refinement GPCR & membrane protein homology Loop refinement & model repair Docking/MD-ready structures
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We validate — not just predictPAE, pLDDT, MolProbity, Ramachandran, and active-site geometry checks. We tell you if the model is fit for purpose.
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Hard targets are our nicheGPCRs, ion channels, transporters, and antigens with missing loops or non-standard residues — where AlphaFold3 still underperforms.
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Built for downstream decisionsRefined structures for molecular docking, MD simulation, or epitope mapping. We deliver models that survive the next step.

Beyond commodity prediction: what we actually do

Quality assessment

AlphaFold model audit

We benchmark your model against expected geometry, PAE/pLDDT confidence, and known experimental constraints. You get a clear fit-for-purpose verdict.

  • PAE / pLDDT interpretation
  • MolProbity & stereochemistry
  • Active-site integrity checks
Refinement

Loop & side-chain repair

Missing loops, clashes, or wrong rotamers? We rebuild and refine using MODELLER, Rosetta, or MD-based relaxation to produce a physically realistic model.

  • Loop modeling & ab initio insertion
  • Side-chain repacking
  • Energy minimization & MD refinement
Hard targets

GPCR & membrane protein modeling

We specialize in receptors, channels, and transporters — targets where AlphaFold3 still struggles with conformational states and ligand-ready pockets.

  • Homology modeling with low identity templates
  • Membrane insertion & orientation
  • Ensemble generation for docking
Hybrid methods

Integrative modeling with experimental data

We incorporate crosslinking, HDX, or mutagenesis data to steer modeling and validate the final ensemble.

  • Distance restraints from XL-MS
  • Solvent accessibility from HDX
  • Mutagenesis-guided docking
Downstream

Structures ready for docking & MD

We deliver models with protonation states, missing hydrogens, and force-field-consistent geometry — ready for your simulation pipeline.

  • Protonation & tautomer assignment
  • Force field preparation (AMBER/GROMACS)
  • Binding-site druggability analysis
Decision support

Benchmarking & candidate ranking

When multiple models exist, we compare and rank them using consensus metrics and downstream test cases.

  • Ensemble clustering & scoring
  • Docking enrichment tests
  • MD stability screening

Core computational techniques

Prediction & validation

AlphaFold2 & deep-learning folding

We run state-of-the-art predictors, then rigorously assess model quality with orthogonal metrics.

  • AlphaFold2 pipelines
  • PAE / pLDDT / PAE-weighted scoring
  • Model comparison & consensus
Classical modeling

Homology & threading

When templates exist but are remote, we use MODELLER, SWISS-MODEL, and threading to build reliable models.

  • Template search & alignment
  • MODELLER / SWISS-MODEL
  • Loop & side-chain optimization
Refinement & dynamics

MD-based model refinement

We relax models in explicit solvent to remove clashes and capture conformational flexibility for downstream use.

  • AMBER / GROMACS refinement
  • Ensemble generation for docking
  • Stability assessment

Protein modeling & validation workflow

Target intake & fit-for-purpose definition

We discuss your downstream goal — docking, MD, epitope mapping, or publication — and define what “good enough” means for your target.

Sequence analysis & template/predictor selection

We run AlphaFold2 or homology modeling based on target difficulty, then assess initial model quality.

Model quality audit & confidence mapping

PAE, pLDDT, MolProbity, Ramachandran, and active-site geometry checks. We identify unreliable regions.

Refinement of problematic regions

Loop rebuilding, side-chain repacking, and MD-based relaxation for hard targets (GPCRs, membrane proteins, antibodies).

Validation against experimental data (if available)

We cross-check with mutagenesis, crosslinking, or HDX data. When no data exists, we use ensemble consistency and energy metrics.

Delivery: decision-ready structure & report

Final models with validation metrics, confidence maps, and recommendations for downstream use (docking, MD, or experimental design).

Integration with downstream workflows

We prepare the structure for docking or MD — protonation, force field parameters, and binding-site analysis.

Which protein modeling challenge can we address?

ChallengeComputational approachKey deliverablesWet-lab validation (optional)
Is my AlphaFold model good enough for docking?PAE/pLDDT audit + active-site geometry + docking testFit-for-purpose report, confidence mapSPR / ITC (binding validation)
GPCR or membrane protein with low homologyHomology modeling + MD refinement + ensemble generationRefined model, conformational ensembleHDX / crosslinking
Missing loops or non-natural residuesLoop modeling, Rosetta design, MD relaxationRepaired structure, energy scoresCircular dichroism
Need a structure for publicationMulti-method validation + experimental cross-checkPublication-ready figures, methodsMutagenesis validation

What we need from you

  • Protein sequence (FASTA) or PDB file if available
  • Downstream application: docking, MD, epitope mapping, etc.
  • Any experimental data (mutagenesis, crosslinking, HDX)
  • Known ligands or binding partners
  • Target family information (GPCR, kinase, protease, etc.)
  • Preferred force field or simulation parameters

What you receive

  • Validated 3D model with confidence metrics (PAE, pLDDT, MolProbity)
  • Fit-for-purpose report and reliability map
  • Refined structures for docking/MD
  • Conformational ensemble if applicable
  • Recommendations for experimental validation
  • Publication-ready figures and methods

Why choose CD ComputaBio for protein modeling?

We are not a prediction shop. We are a structure intelligence partner that helps you decide when a model is reliable, when it needs refinement, and how to use it for downstream discovery.

AlphaFold-awareWe validate and refine AI models — not just run them
Hard-target focusGPCRs, membrane proteins, and low-homology targets are our specialty
Decision-readyStructures prepared for docking, MD, and experimental design

References

  1. Jumper J, Evans R, Pritzel A, et al. Highly accurate protein structure prediction with AlphaFold. Nature 2021, 596: 583–589.
  2. Chen J, Siu S W I. Machine learning approaches for quality assessment of protein structures. Biomolecules 2020, 10(4): 626.
  3. Liu X, Xue Z, Luo M, et al. Anesthetic drug discovery with computer-aided drug design and machine learning. Anesthesiology and Perioperative Science 2024, 2(1): 7.

Frequently Asked Questions

Can't I just use AlphaFold2 or ColabFold for free?

Yes — and for many easy targets, that's sufficient. But raw predictions often have unreliable loops, wrong side-chain rotamers, or poor active-site geometry. If you need the structure for docking, MD, or publication, validation and refinement are essential. We provide that layer.

How do you validate a model without an experimental structure?

We use orthogonal metrics: PAE/pLDDT confidence, MolProbity stereochemistry, Ramachandran analysis, active-site geometry, and ensemble consistency from MD. When experimental data exists (mutagenesis, crosslinking), we incorporate it as restraints.

What makes a target “hard” for AlphaFold?

GPCRs, membrane proteins, targets with missing loops, non-natural modifications, and low-homology sequences. AlphaFold3 has improved but still struggles with conformational states, ligand-ready pockets, and multi-domain assemblies.

Do you provide models ready for docking or MD?

Yes. We deliver structures with correct protonation, missing hydrogens added, and force-field-consistent geometry — ready for AMBER, GROMACS, or docking pipelines. We also offer downstream integration.

What is the turnaround time?

A standard model audit and refinement takes 1–2 weeks. Hard targets with extensive loop rebuilding or MD refinement may take 3–4 weeks. Please contact us with your target details.

Ready to turn a model into a decision?

Share your sequence and downstream goal. We'll tell you if your current model is good enough — and if not, we'll refine it until it is.

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