Insight into the Supramolecular Architecture of Intact Diatom Biosilica from DNP-Supported Solid-State NMR Spectroscopy

Diatom biosilica is an inorganic/organic hybrid with interesting properties. The molecular architecture of the organic material at the atomic and nanometer scale has so far remained unknown, in particular for intact biosilica. A DNP‐supported ssNMR approach assisted by microscopy, MS, and MD simulations was applied to study the structural organization of intact biosilica. For the first time, the secondary structure elements of tightly biosilica‐associated native proteins in diatom biosilica were characterized in situ. Our data suggest that these proteins are rich in a limited set of amino acids and adopt a mixture of random‐coil and β‐strand conformations. Furthermore, biosilica‐associated long‐chain polyamines and carbohydrates were characterized, thereby leading to a model for the supramolecular organization of intact biosilica. Heart of glass: A DNP‐supported ssNMR approach assisted by microscopy, mass spectrometry, and molecular dynamics simulations was applied to study the structural organization of intact biosilica. First insight into the in situ secondary structure elements of tightly biosilica‐associated native proteins was obtained. Based on the results, a novel model for the location and supramolecular arrangement of intact biosilica is suggested.