Biominerals are hybrid materials consisting of organic and inorganic constituents. Understanding the molecular structure of the interface between organic and inorganic constituents of biominerals is a main goal in biomineralization research. The interactions between organic and inorganic components are assumed to be of key importance for the formation of the remarkable structures of biominerals as well as their outstanding materials properties. Solid-state NMR spectroscopy is very well suited to investigate the organic-inorganic interface in biominerals as it allows for the detection of local interactions such as the magnetic dipole-dipole interaction which are strongly distance-dependent. This project aims to study of the structure and formation of the organic-inorganic interface as well as the characterization of the intermolecular interactions at this interface. The investigations will be performed following two routes: (i) Spectroscopic investigations of the intact, extracted diatom cell walls (isotope-labeled with ¹³C, ¹⁵N and ²⁹Si) to identify the biomolecules that are located at the interface, and determine their types of interaction (Covalent bonding or not?). (ii) In vitro studies of organic matrices, their interactions with long-chain polyamines (LCPA) and their mineralization activities using ²⁹Si-labeled silicic acid under physiologically relevant conditions. These studies are expected to answer a variety of key questions in silica biomineralization research including a molecular understanding of the interaction between insoluble organic matrices and soluble biomolecules, and the molecular mechanism through which they influence the silica polycondensation process. Analysis of such reconstituted in vitro systems is indispensable for elucidating the interactions and mechanism that are in operation during silica biomineralization in the living diatom cell.

In the last years, Solid-state NMR (ssNMR) has made important progress in studying complex biomolecules. For example a revolution has taken place in reference to ssNMR sensitivity due to wide-spread use of Dynamic Nuclear Polarization (DNP) that reduces measurement times by several orders of magnitude. Likewise, multidimensional ssNMR in combination with ultra-high field and proton detection provides unprecedented opportunities to study complex biomaterials.
In our project we will make use of such methods to elucidate the native structure of silica-associated proteins by conducting High-field solid-state NMR (ssNMR) and DNP measurements on labelled (¹³C,¹⁵N,²⁹Si-)
T. pseudonana-Biosilicates. In addition, we want to elucidate the structure of the novel membrane protein Sin1 by such methods.

For further information see also:
Jantschke A, et al., Angew Chem Int Ed Engl. 2015 Dec 7;54(50):15069-73
Kaplan M, et al. , Q Rev Biophys. 2016 Jan;49:e15
Kaplan et al., Cell. 2016 Nov 17;167(5):1241-1251