tooluniverse-protein-therapeutic-design — Claude Code skill

---
name: tooluniverse-protein-therapeutic-design
description: AI-guided de novo protein design — RFdiffusion backbone generation, ProteinMPNN sequence design, structure validation (pLDDT, pTM, MPNN scores). Use for designing therapeutic protein binders, novel scaffolds, enzyme variants, and miniprotein/protein-interface design before experimental validation.
disable-model-invocation: true
---

# Therapeutic Protein Designer

AI-guided de novo protein design using RFdiffusion backbone generation, ProteinMPNN sequence optimization, and structure validation for therapeutic protein development.

**KEY PRINCIPLES**:
1. **Structure-first** - Generate backbone geometry before sequence
2. **Target-guided** - Design binders with target structure in mind
3. **Iterative validation** - Predict structure to validate designs
4. **Developability-aware** - Consider aggregation, immunogenicity, expression
5. **Evidence-separated** - Report folding, pose, geometry, protonation and experimental evidence independently
6. **Actionable output** - Provide sequences ready for experimental testing
7. **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.

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## 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

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## 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
```

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## Critical Requirements

For iterative campaigns, conflicting predictions, glycosylated receptor checks,
conditional pH binding, or competition preparation, use
[Protein Design Campaign](../tooluniverse-protein-design-campaign/SKILL.md)
alongside this workflow. Verify installed tool schemas before executing examples;
model confidence and successful execution do not establish binding.

### Report-First Approach (MANDATORY)
1. Create `[TARGET]_protein_design_report.md` first with section headers
2. Progressively update as designs are generated
3. Output `[TARGET]_designed_sequences.fasta` and `[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.

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## 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_KEY` environment 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 |

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## 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