Abstract
In this paper, we use our quantitative (31)P NMR spin trapping methods, already developed for simple oxygen- and carbon-centered radicals, to understand the radical intermediates generated by enzymatic systems and more specifically lipoxygenases. Our methodology rests on the fact that free radicals react with the nitroxide phosphorus compound, 5-diisopropoxy-phosphoryl-5-methyl-1-pyrroline-N-oxide (DIPPMPO), to form stable radical adducts, which are suitably detected and accurately quantified using (31)P NMR in the presence of a phosphorus containing internal standard. This system was thus applied to better understand the mechanism of enzymatic oxidation of linoleic acid by soybean lipoxygenases-1 (LOX). The total amount of radicals trapped by DIPPMPO was detected by (31)P NMR at different experimental conditions. In particular the effect of dioxygen concentration on the amount of radicals being trapped was studied. At low dioxygen concentration, a huge increase of radicals trapped was observed with respect to the amount of radicals being trapped at normal dioxygen concentrations.
Water proton spin saturation affects measured protein backboneN spin relaxation rates
Water proton spin saturation affects measured protein backboneN spin relaxation rates
Publication year: 2011
Source: Journal of Magnetic Resonance, Available online 1 October 2011</br>
Kang*Chen, Nico*Tjandra</br>
Protein backboneN NMR spin relaxation rates are useful in characterizing the protein dynamics and structures. To observe the protein nuclear-spin resonances a pulse sequence has to include a water suppression scheme. There are two commonly employed methods, saturating or dephasing the water spins with pulse field gradients and keeping them unperturbed with flip-back pulses....
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[Question from NMRWiki Q&A forum] Beginner: Help understanding 3D NOESY
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Hi, I am a person with a Computer Science background who is dealing with some NMR dataset. I am concerned with the assignment of NMR peaks from several experiments. For structure determination, I am dealing with 3D-NOESY data. I am finding it a little hard to comprehend what the several peaks mean here. I understand what the peaks in a 2D dataset like 1H-1H NOESY dataset mean but not on higher dimensions.
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Understanding the radical mechanism of lipoxygenases using 31P NMR spin trapping.
Linear Mode
