assoz.-Prof. Dr. Martin Tollinger
NMR Spectroscopy
We investigate time-dependent and dynamic phenomena in complex systems. For this purpose, we experimentally utilise NMR spectroscopy (nuclear magnetic resonance spectroscopy), which enables us to observe and quantify the temporal course of chemical reactions with atomic resolution. This provides us with an in-depth understanding of the factors that determine the efficiency of chemical reactions. We are particularly interested in biological systems, mainly proteins and protein complexes. These biomolecules act as highly specialised and efficient catalysts for a wide range of chemical reactions. They are also characterised by their structural dynamics, an essential property for their function, which can be investigated by NMR spectroscopy. Due to their complexity, biomolecules represent an experimental challenge that requires the use of high-field NMR spectroscopy.
NMR spectroscopy offers the possibility of characterising the chemical conversion of compounds by catalytically active proteins (enzymes). It is possible to observe both the reaction process itself and structural changes in the enzyme during the catalytic reaction. Current examples from our research group concern the degradation of ribonucleic acids by PR-10 proteins, a family of ribonucleases that is widespread in nature. For the first time, we were able to characterise the mechanism of RNA degradation for this protein family in detail. In the first step, single-stranded RNA segments are bound into a cavity of the PR-10 proteins. Only in the second step the RNA chain is hydrolytically cut into fragments on the protein surface and released.
Single-stranded RNA bound to a PR-10 protein. NMR spectroscopic identification of the catalytically active centres on the protein surface.
Biomolecules are characterised by their inherent structural dynamics, which are functionally related to their function. Our research focusses on the structural dynamics of proteins in the millisecond to microsecond range. In this time window, local rearrangements of the three-dimensional structure take place, which enable the binding of bioactive compounds (ligands, enzyme substrates, etc.). NMR spectroscopy allows spatially resolved and quantitative observation of these structural dynamics. The combination with other biophysical methods makes the relationship between structural dynamics and binding affinity experimentally accessible.
NMR relaxation dispersion measurements for the characterisation of functional structural dynamics in biocatalysis.
We are engaged in the development and optimisation of NMR spectroscopic methods, in particular for the quantitative investigation of dynamic phenomena. We are particularly interested in the binding of low molecular weight compounds (ligands) to biological targets. The dynamic process of association and dissociation can be analysed by nuclear spin relaxation measurements on the ligand molecule using a method developed by us. The quantification of the association and dissociation process makes it possible to determine the residence time of the ligand in the complex, a key parameter for optimising the efficiency of bioactive compounds. In addition, thermodynamic data on complex formation can be determined.