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Oral 08
Abstract
Relaxometry for solution DNP <strong>and</strong> protein dynamics
Giacomo Parigi
Magnetic Resonance Center (CERM), University of Florence,
Via Luigi Sacconi 6, 50019 Sesto Fiorentino, Italy
The analysis of the relaxation profiles of paramagnetic complexes in solution
represents a valuable way for the characterization of polarizing agents for solution DNP
experiments. The relaxation profiles of solvent water protons in the presence of nitroxide
radicals or paramagnetic metal complexes have been analyzed to obtain the structural <strong>and</strong>
dynamic parameters needed for determining the coupling factor, on which the solvent DNP
enhancement mainly depends [1-5]. 1 H relaxometry thus represents an easy way to estimate
the DNP enhancement achievable at full electron saturation as a function of the applied
magnetic field.
Relaxivity profiles can provide reorientation times of solute molecules up to the
microsecond range, so that the tumbling time of proteins as large as hundreds kDa can be
accessed [6]. In sedimented proteins [7], they can provide information on the intervening
motions [8].
Recent applications of relaxometry also comprise the analysis of the spectral density
of water protons for the characterization of contrast agents [9], <strong>and</strong> for acquiring information
on protein aggregation <strong>and</strong> dynamics in folded <strong>and</strong> intrinsically disordered proteins. The
analysis of the collective spectral density of protein protons in D 2 O solutions is also feasible
[10] to obtain information on protein dynamics in terms of reorientation time <strong>and</strong> generalized
order parameter.
[1] P. Höfer, G. Parigi, C. Luchinat, P. Carl, G. Guthausen, M. Reese, T. Carlomagno, C. Griesinger, M.
Bennati, “Field Dependent Dynamic Nuclear Polarization with Radicals in Aqueous Solution”, J. Am. Chem.
Soc. (2008) 130, 3254-3255.
[2] M. Bennati, C. Luchinat, G. Parigi, M.-T. Türke, “Water proton relaxation dispersion analysis on a nitroxide
radical provides information on the maximal signal enhancement in Overhauser Dynamic Nuclear Polarization
experiments”, Phys.Chem.Chem.Phys. (2010) 12, 5902-5910.
[3] M.-T. Türke, G. Parigi, C. Luchinat, M. Bennati, “Overhauser DNP with 15 N labelled Frémy’s salt at 0.35
Tesla”, Phys. Chem. Chem. Phys. (2012) 14, 502-510.
[4] P. Neugebauer, J.G. Krummenacker, V.P. Denysenkov, G. Parigi, C. Luchinat, T.F. Prisner, “Liquid State
DNP of Water at 9.2 T: An Experimental Access to Saturation” Phys. Chem. Chem. Phys (2013) in press.
[5] C. Luchinat, G. Parigi, E. Ravera, “Can metal ion complexes be used as polarizing agents for solution DNP?
A theoretical discussion” J. Biomol. NMR (2013) in press.
[6] E. Ravera, G. Parigi, A. Mainz, T.L. Religa, B. Reif, C. Luchinat, “Experimental determination of
microsecond reorientation correlation times in protein solutions”, J. Phys. Chem. B (2013) in press.
[7] I. Bertini, C. Luchinat, G. Parigi, E. Ravera, B. Reif, P. Turano, “Solid State NMR of proteins sedimented by
ultracentrifugation”, Proc. Natl. Acad. Sci. USA (2011) 108, 10396-10399.
[8] C. Luchinat, G. Parigi, E. Ravera, “Water <strong>and</strong> protein dynamics in sedimented systems: a relaxometric
investigation”, ChemPhysChem (2013) in press
[9] D.J. Mastarone, V.S.R. Harrison, A.L. Eckermann, G. Parigi, C. Luchinat, T.J. Meade, “A Modular System
for the Synthesis of Multiplexed Magnetic Resonance Probes”, J. Am. Chem. Soc. (2011) 133, 5329-5337.
[10] C. Luchinat, G. Parigi, “Collective relaxation of protein protons at very low magnetic field: a new window
on protein dynamics <strong>and</strong> aggregation”, J. Am. Chem. Soc. (2007) 129, 1055-1064.
<strong>8th</strong> <strong>Conference</strong> on Fast Field Cycling NMR Relaxometry, Turin 23-25 May 2013