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On fine-tuning Boltz-2 for protein-protein affinity prediction

Published: December 6, 2025 | arXiv ID: 2512.06592v1

By: James King , Lewis Cornwall , Andrei Cristian Nica and more

Potential Business Impact:

Helps predict how proteins stick together.

Business Areas:
A/B Testing Data and Analytics

Accurate prediction of protein-protein binding affinity is vital for understanding molecular interactions and designing therapeutics. We adapt Boltz-2, a state-of-the-art structure-based protein-ligand affinity predictor, for protein-protein affinity regression and evaluate it on two datasets, TCR3d and PPB-affinity. Despite high structural accuracy, Boltz-2-PPI underperforms relative to sequence-based alternatives in both small- and larger-scale data regimes. Combining embeddings from Boltz-2-PPI with sequence-based embeddings yields complementary improvements, particularly for weaker sequence models, suggesting different signals are learned by sequence- and structure-based models. Our results echo known biases associated with training with structural data and suggest that current structure-based representations are not primed for performant affinity prediction.

Page Count
6 pages

Category
Computer Science:
Machine Learning (CS)