Intramolecular Electron Transfer in Azurin: Difference between revisions
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The studies discussed here involve the intramolecular ET between a one electron reduced disulfide anion radical and the oxidized copper ion. In order to measure the rate constant for this process, the disulfide radical must be produced rapidly by a strong reductant in a bimolecular reaction. This bimolecular reaction must reduce the disulfide preferentially over the Cu<sup>2+</sup> site. Azurin shows this preferential reactivity due to the lack of exposure of the copper site, with only part of the edge of the <scene name='70/703985/Az_cu_site_expsoure/1'>His 117exposed</scene> coupled with high exposure of the disulfide | The studies discussed here involve the intramolecular ET between a one electron reduced disulfide anion radical and the oxidized copper ion. In order to measure the rate constant for this process, the disulfide radical must be produced rapidly by a strong reductant in a bimolecular reaction. This bimolecular reaction must reduce the disulfide preferentially over the Cu<sup>2+</sup> site. Azurin shows this preferential reactivity due to the lack of exposure of the copper site, with only part of the edge of the <scene name='70/703985/Az_cu_site_expsoure/1'>His 117exposed</scene> coupled with high exposure of the disulfide | ||
<scene name='70/ | <scene name='70/706737/Az_ss_site_exposure/2'>Cys 3-Cys 26</scene>. | ||
The reducing agent typically used is the CO<sub>2</sub><sup>-</sup> anion radical, an especially strong reducing agent produced by pulse radiolysis of formate containing solutions. Thus the electrostatic interaction with the sites is also relevant. The <scene name='70/703985/Az_cu_site_expsoure_charges/1'>copper site</scene> has no charges near the exposed His46 but the disulfide site <scene name='70/703985/Az_ss_site_expsoure_charges/1'>disulfide site</scene> has both a positive residue (Lys 27) and a negative one (Glu 2)nearby. | The reducing agent typically used is the CO<sub>2</sub><sup>-</sup> anion radical, an especially strong reducing agent produced by pulse radiolysis of formate containing solutions. Thus the electrostatic interaction with the sites is also relevant. The <scene name='70/703985/Az_cu_site_expsoure_charges/1'>copper site</scene> has no charges near the exposed His46 but the disulfide site <scene name='70/703985/Az_ss_site_expsoure_charges/1'>disulfide site</scene> has both a positive residue (Lys 27) and a negative one (Glu 2) nearby. | ||
== Electron transfer path == | == Electron transfer path == | ||
