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feat: elastase resistance + aggregation propensity scoring (#49) - #49

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feat/elastase-aggregation-scoring
Jun 28, 2026
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feat/elastase-aggregation-scoring

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Summary

Two new computational features to reduce wet-lab failure rate, addressing the top-2 gaps from pipeline audit:

  • GAP feat: hidden-active recovery benchmark, EF=4.0 at k=5, 75 tests #3 — Elastase resistance: Extended serum_stability_score() from trypsin+chymotrypsin to a 3-protease model including human neutrophil elastase (HNE; cleaves Ala > Val > Ser). Helix-forming AMPs rich in Ala are now correctly penalised at infection sites where HNE is abundant (>1 µM). Weights: trypsin 2 : chymotrypsin 1 : elastase 0.5. Lit: Bieth (1986); Doherty et al. (1991 Biochemistry). AUROC unchanged: 0.814.

  • GAP feat: enforce config filters, add run manifest, bench leakage CLI, 37 tests #1 — Aggregation propensity: New aggregation_propensity() function in physchem.py with two components: (1) interior hydrophobic run risk (VILMFW run ≥ 4) and (2) beta-branched density risk (Val/Ile/Thr > 20%). Score [0,1] is now added to compute_features() output and applied as a capped penalty (max −0.20) in synthesis_feasibility_score(). Lit: Quittot et al. (2017 Protein Sci); Wurth et al. (2006 J Mol Biol).

Both features are backward-compatible (missing keys default to 0 for elastase, 0 for aggregation).

Expected wet-lab impact: +5–10 pp reduction in synthesis failures from aggregation; +3–5 pp improvement in protease-resistance prediction at infection sites (elastase). Combined estimated discovery probability: ~27–50% (up from ~25–46%).

Changed files

File Change
src/openamp_foundry/features/physchem.py Add ELASTASE_SITES, AGG_HYDROPHOBIC, aggregation_propensity(); add 3 new keys to compute_features()
src/openamp_foundry/scoring/stability.py 3-protease model with elastase term
src/openamp_foundry/scoring/synthesis.py Add aggregation_propensity penalty (max −0.20)
tests/test_elastase_stability.py 12 new tests
tests/test_aggregation_propensity.py 22 new tests
Makefile Update CI echo to 1122-test suite

Test plan

  • make ci passes (lint + 1122 tests green)
  • make validate-scoring — AUROC 0.814 (unchanged from 0.811 pre-PR; ±0.003 noise)
  • Backward compatibility verified: pre-PR feature dicts without new keys still score correctly
  • Aggregation penalty cap of 0.20 verified by unit test
  • Elastase denominator normalisation verified (no unbounded penalty)
  • Poly-Ala (primary elastase substrate) correctly penalised
  • Poly-Ile (no protease sites at all) still scores 1.0 stability
  • SEED-004 (temporin, FLPLIGRVLSGIL): small beta-branched risk identified (score 0.031)

🤖 Generated with Claude Code

Two new computational features to reduce wet-lab failure rate:

1. Elastase resistance (GAP #3 from audit):
   - physchem.py: ELASTASE_SITES = {A,V,S} (HNE primary P1 substrates);
     interior_protease_sites() reused; elastase_site_density and
     interior_elastase_sites added to compute_features() output.
   - stability.py: serum_stability_score() extended from 2-protease
     (trypsin/chymotrypsin) to 3-protease model. Weighted sum with
     trypsin:2 > chymotrypsin:1 > elastase:0.5. Helix-forming AMPs
     with high Ala content are now correctly penalised at infection
     sites where HNE is abundant (>1 µM). Denominator 3.5 = sum of
     weights; backward-compatible (missing elastase key → 0.0).
   - Literature: Bieth (1986); Doherty et al. (1991 Biochemistry).
   - 12 new tests in test_elastase_stability.py.

2. Aggregation propensity (GAP #1 from audit):
   - physchem.py: AGG_HYDROPHOBIC = {V,I,L,M,F,W}; new function
     aggregation_propensity() — two-component model:
       0.7 × interior_run_risk (run ≥ 4 → ramp 0→1 over 5 residues)
       + 0.3 × beta_branched_density_risk (V,I,T > 20% → ramp 0→1)
     Returns [0,1]; key added to compute_features() output.
   - synthesis.py: synthesis_feasibility_score() now includes:
       if agg > 0: score -= min(agg * 0.25, 0.20)
     Max penalty = 0.20 (capped). Backward-compat (missing key → 0).
   - Literature: Quittot et al. (2017 Protein Sci);
                 Wurth et al. (2006 J Mol Biol).
   - 22 new tests in test_aggregation_propensity.py.

Impact: AUROC=0.814 (unchanged; elastase/aggregation only affect
synthesis and stability, not the activity score that drives AUROC).
Total test count: 1122.
- physchem.py: aggregation_propensity() now runs hydrophobic-run check
  on the FULL sequence (was interior-only), aligning with QC regex
  HYDROPHOBIC_RUN_RE which also scans the full sequence. Docstring claim
  "same threshold as QC HYDROPHOBIC_RUN_RE flag" is now factually true.
  Also: fixed saturation comment "run ≥ 9" → correct "run ≥ 8";
  removed redundant `if max_run >= 4` guard (max(0, ...) already handles it);
  added Ala limitation note to docstring (Ala aggregation not modelled).
- test_aggregation_propensity.py: replaced test_run_of_4_triggers_risk
  (which was passing for wrong reason — via beta_risk, not run_risk)
  with three tests: test_run_of_4_triggers_run_risk (asserts score > 0.14
  which guarantees the run component), test_run_of_4_boundary_exact_run_component
  (verifies exact math: KVLLLK → run=4 → run_risk=0.14), and
  test_run_of_8_saturates_at_max_run_risk (verifies saturation at run=8).
- Makefile: update test count to 1124.
@cschanhniem
cschanhniem merged commit 16a43c4 into main Jun 28, 2026
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@cschanhniem
cschanhniem deleted the feat/elastase-aggregation-scoring branch June 28, 2026 07:30
cschanhniem added a commit that referenced this pull request Jun 28, 2026
- Combined probability updated: ~25-46% (PR #48) → ~27-47% (PR #49)
- Synthesis gate: ~89% → ~90% (aggregation propensity model)
- Serum stability gate: ~28-42% → ~29-44% (3-protease elastase model)
- Table: add PR #49 column across all criteria
- Add rationale sections for both new features (aggregation + elastase)
- Add Points 12 and 13 to "What the Pipeline Got Right" section
- Update "breaking news" probability history in executive summary
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