Abstract

The solvent proton longitudinal (spin-lattice) relaxation time (1/T1M) of a paramagnetic contrast agent is directly related to the image contrast in medical magnetic resonance imaging (MRI). There are two contributors to proton relaxation, known as inner sphere and outer sphere. Solomon and Bloembergen have shown that the inner sphere proton longitudinal relaxation time is dependent upon three factors, namely the rotational correlation time (gR), the electronic spin-lattice relaxation time (gS), and the lifetime of the water protons in the paramagnetic metal site (gM). Outer-sphere relaxation has been found to depend on the correlation time of the solute and the solvent to diffuse apart (g) and again the electronic spin-lattice relaxation time. However, direct measurements of these components have not been easy to obtain. Nuclear magnetic relaxation dispersion (NMRD) can only provide estimates to the parameters mentioned above. In this study we report the successful employment of electron paramagnetic resonance (EPR), using vanadyl complexed to two different chelates (EDTA and DTPA) as spin probes, in direct measurements of the rotational correlation time. Furthermore, estimates derived from fitting nuclear magnetic relaxation dispersion (NMRD) profiles corroborate the EPR results obtained.

  Funding Agency

Agency
National Institute of Health (NIH)
Institute
National Center for Research Resources (NCRR)
Type
Biotechnology Resource Grants (P41)
Project #
2P41RR001811-11
Application #
5223628
Study Section
Project Start
Project End
Budget Start
Budget End
Support Year
11
Fiscal Year
1996
Total Cost
Indirect Cost

  Publications

Hurth, Kyle M; Nilges, Mark J; Carlson, Kathryn E et al. (2004) Ligand-induced changes in estrogen receptor conformation as measured by site-directed spin labeling. Biochemistry 43:1891-907
Woodmansee, Anh N; Imlay, James A (2002) Reduced flavins promote oxidative DNA damage in non-respiring Escherichia coli by delivering electrons to intracellular free iron. J Biol Chem 277:34055-66
Denisov, Ilia G; Makris, Thomas M; Sligar, Stephen G (2002) Formation and decay of hydroperoxo-ferric heme complex in horseradish peroxidase studied by cryoradiolysis. J Biol Chem 277:42706-10
Atsarkin, V A; Demidov, V V; Vasneva, G A et al. (2001) Mechanism of oxygen response in carbon-based sensors. J Magn Reson 149:85-9
Mangels, M L; Harper, A C; Smirnov, A I et al. (2001) Investigating magnetically aligned phospholipid bilayers with EPR spectroscopy at 94 GHz. J Magn Reson 151:253-9
Breitzer, J G; Smirnov, A I; Szczepura, L F et al. (2001) Redox properties of C6S8(n-) and C3S5(n-) (n = 0, 1, 2): stable radicals and unusual structural properties for C-S-S-C bonds. Inorg Chem 40:1421-9
Denisov, I G; Hung, S C; Weiss, K E et al. (2001) Characterization of the oxygenated intermediate of the thermophilic cytochrome P450 CYP119. J Inorg Biochem 87:215-26
Kirkor, E S; Scheeline, A (2000) Nicotinamide adenine dinucleotide species in the horseradish peroxidase-oxidase oscillator. Eur J Biochem 267:5014-22
Rapoport, N; Smirnov, A I; Pitt, W G et al. (1999) Bioreduction of Tempone and spin-labeled gentamicin by gram-negative bacteria: kinetics and effect of ultrasound. Arch Biochem Biophys 362:233-41
Maringanti, S; Imlay, J A (1999) An intracellular iron chelator pleiotropically suppresses enzymatic and growth defects of superoxide dismutase-deficient Escherichia coli. J Bacteriol 181:3792-802

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