Summary: Three-dimensional structures of biological macromolecules form the basis for a detailed understanding of biological processes. Nuclear magnetic resonance (NMR) spectroscopy is one method widely used to obtain structural data. In this project we further develop methods that make the application of NMR more efficient. Background: NMR spectroscopy in solution has found wide spread applications in physical, chemical, biological and medical sciences. A prerequisite for the detailed analysis of the information content of NMR spectra are individual assignments of resonances to specific nuclei (atoms). In biological applications, the necessary data is usually obtained from a number of multi-dimensional NMR experiments which correlate signals of 1H, 13C and 15N nuclei in doubly 13C,15N isotope-labeled macromolecules. Often, the data cannot be completely analyzed by automated computer programs and full resonance assignments can only be obtained interactively by an experienced NMR spectroscopist. Recently, a new technique was introduced: APSY (automated projection spectroscopy). APSY is based on projection NMR spectroscopy and it was shown to provide data that can reliably be analyzed by automated programs. For example, for protein spectra fully automated assignments of resonances of nuclei in the backbone and in aliphatic side chains could be obtained. Goal: Based on the experience gained with the use of APSY with proteins we want to apply the APSY technique to another class of macromolecules: RNA and DNA. The assignment of resonances in RNA (DNA) is often challenging especially for automated routines because of the small dispersion of resonances in RNA (DNA) spectra. The application of APSY with denatured proteins has shown that this method can deal very well with poorly resolved spectra. Based on APSY correlation experiments in the bases, sugar and the oligonucleotide backbone, we will design a suite of APSY experiments for automated sequence-specific assignments of resonances in spectra of 13C,15N-labeled RNA (DNA). Significance: The outcome of this work will provide experimental procedures for automated resonance assignment in spectra of biological macromolecules. The methodology will make the application of NMR spectroscopy with this class of molecules more efficient by alleviating a major bottleneck in the analysis of NMR data.
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