[NMR paper] Solid state deuterium NMR study of LK?14 peptide aggregation in biosilica.

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Solid state deuterium NMR study of LK?14 peptide aggregation in biosilica.

Related Articles Solid state deuterium NMR study of LK?14 peptide aggregation in biosilica.

Biointerphases. 2017 Jun 27;12(2):02D418

Authors: Ferreira HE, Drobny GP

Abstract
In nature, organisms including diatoms, radiolaria, and marine sponges use proteins, long chain polyamines, and other organic molecules to regulate the assembly of complex silica-based structures. Here, the authors investigate structural features of small peptides, designed to mimic the silicifying activities of larger proteins found in natural systems. LK?14 (Ac-LKKLLKLLKKLLKL-C), an amphiphilic lysine/leucine repeat peptide with an ?-helical secondary structure at polar/apolar interfaces, coprecipitates with silica to form nanospheres. Previous (13)C magic angle spinning studies suggest that the tetrameric peptide bundles that LK?14 is known to form in solution may persist in the silica-complexed form, and may also function as catalysts and templates for silica formation. To further investigate LK?14 aggregation in silica, deuterium solid-state nuclear magnetic resonance ((2)H ssNMR) was used to establish how leucine side-chain dynamics differ in solid LK?14 peptides isolated from aqueous solution, from phosphate-buffered solution, and in the silica-precipitated states. Modeling the (2)H ssNMR line shapes probed the mechanisms of peptide preaggregation and silica coprecipitation. The resulting NMR data indicates that the peptide bundles in silica preserve the hydrophobic interior that they display in the hydrated solid state. However, NMR data also indicate free motion of the leucine residues in silica, a condition that may result from structural deformation of the aggregates arising from interactions between the surface lysine side chains and the surrounding silica matrix.


PMID: 28655279 [PubMed - in process]



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