Residue-Resolved Liquid-State Hyperpolarized NMR of Peptide Condensate Surfaces

Understanding how biomolecular condensates interact with their environment requires atomic-level insights into their surface composition. However, conventional Nuclear Magnetic Resonance (NMR) spectroscopy lacks the sensitivity to probe solvent-exposed regions in large, phase-separated peptide systems, where surface moieties are sparse relative to bulk residues. Here, we introduce hyperpolarized liquid-state surface-specific NMR spectroscopy, a technique that visualizes solvent-accessible residues in large biomolecular condensates. In combination with unconventional sample handling instrumentation and hyperpolarization-specific data processing, we report high-resolution hyperpolarized surface NMR spectra with spectral qualities that do not fall short of cutting-edge high-field methods yet have substantially boosted sensitivity. Targeting the biotechnologically widely used elastin-like polypeptide (ELP) nanoscale complexes, we demonstrate residue-resolved detection of the water interface of mega Dalton-sized peptide condensates with sensitivity enhancements reaching 2 orders of magnitude. Our method reveals glycine residues at the coacervate surface while hydrophobic core residues remain suppressed, providing direct evidence for glycine-rich surface segregation in these biomaterials. These findings resolve long-standing questions about ELP surface architecture and open an avenue for a solution-state analog to surface-enhanced solid-state NMR. The presented advance might thus foster detailed investigations of soft-matter interfaces in protein condensates, synthetic coacervates, and bioengineered materials.