Nuclear Magnetic Resonance (NMR) at CIC bioGUNE

Áreas de investigación
  • Physical Sciences

Tammo Diercks Email: Teléfono: 946.572.513

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The NMR paltform at CIC bioGUNE features two modern BRUKER AVANCE III spectrometers that are highly complementary and ideally suited for a double-track strategy: The 600 MHz medium-field spectrometer with flexible configuration and ample accessory (including 7 probeheads, dedicated 19F and HR-MAS equipment, automatic sample changer) enables the largest range of NMR experiments beyond standard biomolecular applications The 800 MHz high-field spectrometer with TCI cryo-probe is set up for protein NMR experiments (using 1H, 2H, 13C and 15N nuclei) at highest sensitivity To complement the modern NMR hardware we continuously optimise and further develop NMR experiments for maximal user friendliness, robustness, sensitivity and spectral purity. The two latter aspects often entail new NMR methods development – a core mission and research interest at the NMR platform. Our principal approach to optimise sensitivity and efficiency is the design and implementation of broadband flip-back techniques for unused 1H polarisation. The recovered polarisation is then exploited either unspecifically as a general "cold bath" to accelerate the reequilibration of the sub-polarisation of interest, allowing for faster pulsing with enhanced sensitivity. Alternatively, the recovered polarisation can be exploited specifically, for instance in an immediately appended second scan (experiment). As an example, the qTROSY scheme recovers the 50% anti-TROSY polarisation wasted in conventional TROSY experiments, and exploits it in a second queued TROSY scan: To enhance the spectral purity and clarity, artifact signal pathways are conventionally eliminated by means of pulse phase cycling and pulsed field gradients. Yet, certain undesired magnetisation pathways require explicit and sophisticated filter schemes. For instance, the most important NOESY spectra for structure elucidation are fraught with intense, uninformative diagonal signals that cause spectral overlap, baseline distortions and a plethora of artifacts (e.g., t1 noise, decoupling sidebands). Thus, a main line of methods development at our NMR platform deals with diagonal signal suppression in NOESY spectra. Thus, we have devised single scan suppression schemes by orthogonal spin state selection (oS3), as in the HN,NH TROSY-NOESY-TROSY and HC,CH HSQC-NOESY-HSQC. Diagonal signal suppression can be so complete as to allow observation of superimposed degenerate NOE signals, for instance from ipso contacts between same nuclei across dimer interfaces. We furthermore develop novel experiments, mainly in the field of biomolecular NMR. For example, we have devised a generalised scheme for including indirect 1H dimensions into TROSY type experiments that avoids the deleterious scrambling of HN spin states without the use of selective 1H pulses. As shown by the novel HN[CA]HA and HN[COCA]HA TROSY it is now possible to record all classic triple resonance experiments for sequential assignment as TROSY instead of HSQC versions. Finally, an important and vast research topic pursued at the NMR platform in close collaboration with inhouse and external partners is the introduction of 19F into biomolecular NMR studies on protein-ligand interactions. While our partners deal with the often difficult and demanding task of synthesising the required fluorinated compounds, we develop appropriate 19F NMR experiments. Thus we have devised the powerful STDreF (1H,1H STD relayed to 19F) experiment to study, e.g., the interaction between proteins and fluorinated carbohydrates with superior specificity and spectral resolution (allowing straightforward distinction of anomers), and free from the ubiquitous and problematic 1H background.


CIC bioGUNE Bizkaia Technology Park Structural Unit Building 800 48160 Derio (Bizkaia)