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arXiv 2602.24007q-bio.BMcs.LG
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推断时间优化用于实验导向的蛋白质集合生成

Inference-time optimization for experiment-grounded protein ensemble generation

Advaith Maddipatla, Anar Rzayev, Marco Pegoraro, Martin Pacesa, Paul Schanda, Ailie Marx, Sanketh Vedula, Alex M. Bronstein

AI总结:

本文提出一种推断时间优化框架,通过优化潜在表示和新型采样方案,提升蛋白质集合生成的多样性、物理能量和与实验数据的一致性。

摘要:

蛋白质功能依赖于动态构象集合,但当前生成模型如AlphaFold3常无法生成与实验数据匹配的集合。近期的实验引导生成器尝试通过引导反扩散过程来解决这一问题,但受限于固定的采样时间跨度和对初始化的敏感性,往往产生热力学不合理的结果。我们引入了一种通用的推断时间优化框架来解决这些挑战。首先,我们通过优化潜在表示来最大化集合的对数似然,而不是事后扰动结构。这种方法消除了对扩散长度的依赖,去除了初始化偏差,并容易整合外部约束。其次,我们提出了新的采样方案来绘制玻尔兹曼加权集合。通过结合AlphaFold3的结构先验和基于力场的先验,我们从它们的乘积分布中采样,同时平衡实验似然。我们的结果表明,该框架在X射线晶体学和NMR中均优于最先进的引导方法,通常比已提交的PDB结构更符合实验数据。最后,推断时间优化实验最大化ipTM分数表明,扰动AlphaFold3嵌入可以人为提高模型置信度。这暴露了当前设计指标的漏洞,其缓解可能为减少结合物工程中的假阳性率提供途径。

英文摘要:

Protein function relies on dynamic conformational ensembles, yet current generative models like AlphaFold3 often fail to produce ensembles that match experimental data. Recent experiment-guided generators attempt to address this by steering the reverse diffusion process. However, these methods are limited by fixed sampling horizons and sensitivity to initialization, often yielding thermodynamically implausible results. We introduce a general inference-time optimization framework to solve these challenges. First, we optimize over latent representations to maximize ensemble log-likelihood, rather than perturbing structures post hoc. This approach eliminates dependence on diffusion length, removes initialization bias, and easily incorporates external constraints. Second, we present novel sampling schemes for drawing Boltzmann-weighted ensembles. By combining structural priors from AlphaFold3 with force-field-based priors, we sample from their product distribution while balancing experimental likelihoods. Our results show that this framework consistently outperforms state-of-the-art guidance, improving diversity, physical energy, and agreement with data in X-ray crystallography and NMR, often fitting the experimental data better than deposited PDB structures. Finally, inference-time optimization experiments maximizing ipTM scores reveal that perturbing AlphaFold3 embeddings can artificially inflate model confidence. This exposes a vulnerability in current design metrics, whose mitigation could offer a pathway to reduce false discovery rates in binder engineering.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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