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Polarized proton spin density images the tyrosyl radical locations in bovine liver catalase

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ABSTRACT

A tyrosyl radical, as part of the amino acid chain of bovine liver catalase, supports dynamic proton spin polarization (DNP). Finding the position of the tyrosyl radical within the macromolecule relies on the accumulation of proton polarization close to it, which is readily observed by polarized neutron scattering. The nuclear scattering amplitude due to the polarization of protons less than 10 Å distant from the tyrosyl radical is ten times larger than the amplitude of magnetic neutron scattering from an unpaired polarized electron of the same radical. The direction of DNP was inverted every 5 s, and the initial evolution of the intensity of polarized neutron scattering after each inversion was used to identify those tyrosines which have assumed a radical state. Three radical sites, all of them close to the molecular centre and the haem, appear to be equally possible. Among these is tyr-369, the radical state of which had previously been proven by electron paramagnetic resonance.

No MeSH data available.


The chromium(V) complex anion, (2-hydroxy-2-ethylbutyrato) oxo­chromate(V), abbreviated as EHBA–CrV, C12O7H20Cr. The central Cr atom is surrounded by five O atoms (red). C atoms are shown as small black spheres. Large spheres represent H atoms. The close H atoms of the solute within a spherical R1 (dotted circle) are shown in violet.
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fig17: The chromium(V) complex anion, (2-hydroxy-2-ethylbutyrato) oxo­chromate(V), abbreviated as EHBA–CrV, C12O7H20Cr. The central Cr atom is surrounded by five O atoms (red). C atoms are shown as small black spheres. Large spheres represent H atoms. The close H atoms of the solute within a spherical R1 (dotted circle) are shown in violet.

Mentions: One of the basic assumptions in the analysis of data from polarized neutron scattering from dynamically polarized protons in catalase is the existence of a magnetic nuclear spin diffusion barrier. TPP experiments on a small radical molecule in a protiated solvent would not only substantiate this assumption but also provide information on its role in the build-up of proton polarization. It is for this reason that solutions with different concentrations of a chromium(V) complex, abbreviated as EHBA–CrV (Fig. 17 ▸), in glycerol–water mixtures (1/1 v/v) have been studied by the method of TPP.


Polarized proton spin density images the tyrosyl radical locations in bovine liver catalase
The chromium(V) complex anion, (2-hydroxy-2-ethylbutyrato) oxo­chromate(V), abbreviated as EHBA–CrV, C12O7H20Cr. The central Cr atom is surrounded by five O atoms (red). C atoms are shown as small black spheres. Large spheres represent H atoms. The close H atoms of the solute within a spherical R1 (dotted circle) are shown in violet.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5391855&req=5

fig17: The chromium(V) complex anion, (2-hydroxy-2-ethylbutyrato) oxo­chromate(V), abbreviated as EHBA–CrV, C12O7H20Cr. The central Cr atom is surrounded by five O atoms (red). C atoms are shown as small black spheres. Large spheres represent H atoms. The close H atoms of the solute within a spherical R1 (dotted circle) are shown in violet.
Mentions: One of the basic assumptions in the analysis of data from polarized neutron scattering from dynamically polarized protons in catalase is the existence of a magnetic nuclear spin diffusion barrier. TPP experiments on a small radical molecule in a protiated solvent would not only substantiate this assumption but also provide information on its role in the build-up of proton polarization. It is for this reason that solutions with different concentrations of a chromium(V) complex, abbreviated as EHBA–CrV (Fig. 17 ▸), in glycerol–water mixtures (1/1 v/v) have been studied by the method of TPP.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

A tyrosyl radical, as part of the amino acid chain of bovine liver catalase, supports dynamic proton spin polarization (DNP). Finding the position of the tyrosyl radical within the macromolecule relies on the accumulation of proton polarization close to it, which is readily observed by polarized neutron scattering. The nuclear scattering amplitude due to the polarization of protons less than 10 Å distant from the tyrosyl radical is ten times larger than the amplitude of magnetic neutron scattering from an unpaired polarized electron of the same radical. The direction of DNP was inverted every 5 s, and the initial evolution of the intensity of polarized neutron scattering after each inversion was used to identify those tyrosines which have assumed a radical state. Three radical sites, all of them close to the molecular centre and the haem, appear to be equally possible. Among these is tyr-369, the radical state of which had previously been proven by electron paramagnetic resonance.

No MeSH data available.