AI-guided de novo protein design using RFdiffusion backbone generation, ProteinMPNN sequence optimization, and structure validation for therapeutic protein development.
KEY PRINCIPLES:
- Structure-first - Generate backbone geometry before sequence
- Target-guided - Design binders with target structure in mind
- Iterative validation - Predict structure to validate designs
- Developability-aware - Consider aggregation, immunogenicity, expression
- Evidence-separated - Report folding, pose, geometry, protonation and experimental evidence independently
- Actionable output - Provide sequences ready for experimental testing
- English-first queries - Always use English terms in tool calls
Therapeutic protein design starts with the target interaction. What binding surface do you need to cover? A small pocket = nanobody or peptide. A large flat surface = designed protein. Stability, immunogenicity, and manufacturability constrain the design space.
LOOK UP, DON'T GUESS
When uncertain about any scientific fact, SEARCH databases first rather than reasoning from memory. A database-verified answer is always more reliable than a guess.
COMPUTE, DON'T DESCRIBE
When analysis requires computation (statistics, data processing, scoring, enrichment), write and run Python code via Bash. Don't describe what you would do — execute it and report actual results. Use ToolUniverse tools to retrieve data, then Python (pandas, scipy, statsmodels, matplotlib) to analyze it.
When to Use
Apply when user asks to:
- Design a protein binder, therapeutic protein, or scaffold
- Optimize a protein sequence for function
- Design a de novo enzyme
- Generate protein variants for target binding
Workflow Overview
Phase 1: Target Characterization
Get structure (PDB, EMDB cryo-EM, AlphaFold), identify binding epitope
Phase 2: Backbone Generation (RFdiffusion)
Define constraints, generate >= 5 backbones, filter by geometry
Phase 3: Sequence Design (ProteinMPNN)
Design >= 8 sequences per backbone, sample with temperature control
Phase 4: Structure Validation (ESMFold/AlphaFold2)
Predict structure, compare to backbone, assess pLDDT/pTM
Phase 5: Developability Assessment
Aggregation, pI, expression prediction
Phase 6: Report Synthesis
Ranked candidates, FASTA, experimental recommendations
Critical Requirements
For iterative campaigns, conflicting predictions, glycosylated receptor checks, conditional pH binding, or competition preparation, use Protein Design Campaign alongside this workflow. Verify installed tool schemas before executing examples; model confidence and successful execution do not establish binding.
Report-First Approach (MANDATORY)
- Create
[TARGET]_protein_design_report.mdfirst with section headers - Progressively update as designs are generated
- Output
[TARGET]_designed_sequences.fastaand[TARGET]_top_candidates.csv
Design Documentation (MANDATORY)
Every design MUST include: Sequence, Length, Target, Method, and available Quality Metrics (pLDDT, pTM, MPNN score, binding prediction). Mark unavailable metrics unmeasured or uncomputed; do not fabricate binding predictions or experimental values.
NVIDIA NIM Tools
| Tool | Purpose | Key Parameter |
|---|---|---|
NvidiaNIM_rfdiffusion (requires NVIDIA_API_KEY env var; free key at build.nvidia.com) |
Backbone generation | contigs + input_pdb (both required), diffusion_steps (NOT num_steps; default 15) |
NvidiaNIM_proteinmpnn (requires NVIDIA_API_KEY env var; free key at build.nvidia.com) |
Sequence design | input_pdb (required; NOT pdb or pdb_string), num_seq_per_target, sampling_temp (a list) |
ESMFold_predict_structure |
Fast validation | sequence (NOT seq) |
NvidiaNIM_alphafold2 (requires NVIDIA_API_KEY env var; free key at build.nvidia.com) |
High-accuracy structure inference from sequence | sequence, algorithm |
NvidiaNIM_esm2_650m (requires NVIDIA_API_KEY env var; free key at build.nvidia.com) |
Sequence embeddings | sequences, format |
Common Parameter Mistakes
| Tool | Wrong | Correct |
|---|---|---|
NvidiaNIM_rfdiffusion (requires NVIDIA_API_KEY) |
num_steps=50 |
diffusion_steps=50 (plus required contigs and input_pdb) |
NvidiaNIM_proteinmpnn (requires NVIDIA_API_KEY) |
pdb=content or pdb_string=content |
input_pdb=content |
ESMFold_predict_structure |
seq="MVLS..." |
sequence="MVLS..." |
NvidiaNIM_alphafold2 (requires NVIDIA_API_KEY) |
seq="MVLS..." |
sequence="MVLS..." |
NVIDIA NIM Requirements
- API Key:
NVIDIA_API_KEYenvironment variable required - Rate limits: 40 RPM (1.5 second minimum between calls)
- AlphaFold2 may return 202 (polling required); RFdiffusion and ESMFold are synchronous
Supporting Tools
| Tool | Purpose | Key Parameters |
|---|---|---|
PDBe_get_uniprot_mappings |
Find PDB structures | uniprot_id |
RCSBData_get_entry |
Download PDB file | pdb_id |
alphafold_get_prediction |
Get AlphaFold DB structure | accession |
EMDB_search_structures |
Search cryo-EM maps | query |
EMDB_get_structure |
Get entry details | entry_id |
UniProt_get_entry_by_accession |
Get target sequence | accession |
InterPro_get_protein_domains |
Get domains | accession |
Folding and Developability Screening
These are illustrative computational screening tiers, not binding-evidence grades or calibrated success probabilities. Benchmark screening with appropriate controls. Monomer pLDDT/pTM cannot establish a complex pose, affinity, cross-species binding or pH selectivity. Report those dimensions separately, including missing evidence.
| Tier | Criteria |
|---|---|
| T1 (strongest in this screen) | pLDDT >85, pTM >0.8, low aggregation, neutral pI |
| T2 | pLDDT >75, pTM >0.7, acceptable developability |
| T3 | pLDDT >70, pTM >0.65, developability concerns |
| T4 | Failed validation or major developability issues |
Completeness Checklist
- Target structure obtained (PDB or predicted)
- Binding epitope identified
- >= 5 backbones generated, top 3-5 selected
- >= 8 sequences per backbone, MPNN scores reported
- All sequences validated (ESMFold), pLDDT/pTM reported, >= 3 passing
- Developability assessed (aggregation, pI, expression)
- Ranked candidate list, FASTA file, experimental recommendations
Reference Files
- DESIGN_PROCEDURES.md - Phase-by-phase code examples, sampling parameters, fallback chains
- TOOLS_REFERENCE.md - Complete tool documentation with code examples
- EXAMPLES.md - Sample design workflows and outputs
- CHECKLIST.md - Detailed phase checklists and quality metrics
- design_templates.md - Report templates and output format examples