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Code:
TOC
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Time Slot/Poster Number:
10:45-11:10
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Session:
Liquids II Biomolecules
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Experience with Detection of 13C and 15N in Triple Resonance Experiments of Proteins
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| Gerhard Wagner; Sven Hyberts; Dominique Frueh; Zhen-Yu Sun; Koh Takeuchi
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Dept. Biol. Chem. & Mol. Pharmacologie, Boston, MA
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| Abstract |
Performance of triple-resonance experiments on large proteins depends crucially on the transverse relaxation of the involved coherences. For large systems, slow transverse relaxation may be more important than signal intensity. We report 2D and 3D triple resonance experiments that use 13Cα- and 15N detection. For some of the experiments we use alternate 13C labeling to eliminate complications from one-bond carbon-carbon coupling. Experiments have been tested on small model proteins in viscous media to simulate large molecular weight, and on the 52 kDa GST dimer. We use a cryogenic probe optimized for carbon and nitrogen detection.
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Code:
TOC
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Time Slot/Poster Number:
11:10-11:25
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Session:
Liquids II Biomolecules
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Long-lived coherences for homogeneous line-narrowing in spectroscopy
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| Paul Vasos1; Riddhiman Sarkar1; Puneet Ahuja1; Geoffrey Bodenhausen1, 2
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1Swiss Federal Institute of Technology (ISIC, EPFL), Lausanne, Switzerland; 2Ecole Normale Supérieure (ENS), Paris, France
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| Abstract |
Line-broadening, which arises either from inhomogeneous samples or from incoherent homogeneous relaxation effects, is the Achilles’ heel of NMR spectroscopy. It turns out that coherent broadening may be considerably reduced by exploiting long life-times associated with superpositions of quantum states with different symmetry, termed long-lived coherences (LLCs). Very highly-resolved spectra can thus be obtained, with homogeneous line-widths that are much narrower than in conventional spectroscopy. The effect is illustrated by proton nuclear magnetic resonance spectroscopy of proteins in isotropic solution, where the slow oscillatory decays of LLCs yield spectra with considerably improved resolution. The enhancement in resolution may open the way to structural and dynamic NMR studies of macromolecules with a molecular mass significantly beyond the current threshold.
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Code:
TOC
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Time Slot/Poster Number:
11:25-11:50
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Session:
Liquids II Biomolecules
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Modelling symmetric structures from (sparse) distance data
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| Michael Nilges1, 2; Benjamin Bardiaux3; Manuel Campos1; Olivera Francetic1
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1Institut Pasteur, Paris, France; 2CNRS URA 2185, Paris, France; 3Leibniz Institute for Molecular Pharmacology, Berlin, Germany
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| Abstract |
We present new methods for the calculation of symmetric structures displaying symmetries of any kind (point symmetries, general non-crystallographic symmetries, and crystallographic symmetries), based on a combination of specific assignment rules, network anchoring, and adapted structure calculation protocols. The methods are applicable to the calculation of large symmetric aggregates based on structural knowledge of the individual components, low resolution electron microscopy data, and few distance restraints. The method is applied to the determination of models of bacterial pili from type II and type IV secretion systems.
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Code:
TOC
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Time Slot/Poster Number:
11:50-12:05
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Session:
Liquids II Biomolecules
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Measurement of Protein Dynamics by Using Different Modulation Functions of Adiabatic Pulses
in T1rho and T2rho Experiments
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| Silvia Mangia1; Nathaniel Traaseth2; Michael Garwood1; Gianluigi Veglia2, 3; Shalom Michaeli1
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1CMRR - Univ. of Minnesota, Minneapolis, MN; 2Dept. of Mol. Biol. and Bioph., Univ. of Minnesota, Minneapolis, MN; 3Dept. of Chem. and Biochem., Univ. of Minnesota, Minneapolis, MN
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| Abstract |
The aim of the present work was to characterize protein dynamics by measuring rotating frame relaxation time constants, T1rho and T2rho, using adiabatic full passage (AFP) pulses with various modulation functions. While the effects of adiabatic pulse parameters have been rationalized and applied to in-vivo experiments, this is the first application for biomolecular NMR in proteins. We demonstrate the usefulness of this approach in 15N-ubiquitin by solution NMR spectroscopy. The results show that adiabatic T1rho and T2rho are significantly affected by the pulse modulation functions, leading to the possibility of estimating intrinsic dynamic properties. These relaxation measurements provide an alternative approach that may be advantageous compared to other methods for characterizing protein dynamics and for applications with cryoprobes.
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