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Reorganization energy protein

Table 5-6. Comparison of ADEs and VDEs, and inner sphere reorganization energies (A.oxi) (eV) for iron-sulfur protein, Rd... Table 5-6. Comparison of ADEs and VDEs, and inner sphere reorganization energies (A.oxi) (eV) for iron-sulfur protein, Rd...
Basu, G. Kitao, A. Kuki, A. Go, N., Protein electron transfer reorganization energy from normal mode analysis. 1. Theory, J. Phys. Chem. B 1998,102, 2076-2084... [Pg.459]

In the high temperature limit where all the nuclear motions coupled to the process can be described classically, the nuclear factor is expressed in terms of only two parameters the driving force of the reaction AG°, and the whole reorganization energy X (expressions (13) and (14)). Detailed calculations carried out in the case of cytochrome c have demonstrated that AG° is a complex quantity, which depends not only on the electronic properties of the redox centers but also on those of the protein and of the surrounding solvent [100]. Usually, AG can be evaluated from measurements of redox potentials and of eventual interaction energies between the different parts of the systems (Appendix). [Pg.23]

Another important result that was obtained recently concerns the evaluation of the contribution to the reorganization energy arising from the polarization of the medium, protein and solvent from a microscopic model including the residual charges and induced dipoles of the protein as well as bound water molecules, a value of about 0.2 eV was calculated for different eleetron transfer processes [97], This weak value results from the apolar character of the medium, and is compatible with the kinetic data which indicate that reorganization energies are small in the reaction center (Sect. 3.2.2)... [Pg.39]

Electron transfer from Fe(II)cytc to ccp(ES) proceeds with a rate of 800 s at — AG° = 0.90 eV [73]. From measurements of ET rates at other driving forces, the cyt c/ccp reorganization energy was estimated to be 1.5 eV the relatively large X value may be a result of redox-dependent fluctuations of the protein-protein orientation, since the primary binding mode is electrostatic (salt bridges) [73]. [Pg.127]

In all protein-protein complexes studied to date in which cytochrome c has been a partner, it has been shown that the ET rates depend strongly on the reaction driving force. It follows that variations in the reorganization energy could control ET rates in these cases [12]. In redox enzymes with two or more active centers, ET between two centers could be turned on by lowering X at roughly constant — AG [1]. Indeed, a proposal has been advanced that this type of mechanism would be an efficient way to gate the electron flow in a redox-linked proton pump such as cytochrome oxidase [75]. [Pg.127]

A second point of interest is that the A values inferred for high spin Fe(III) complexes (eg Hb) are much larger than those seen for low spin systems (eg cytc). The slow reactions seen for high spin Fe heme proteins likely reflect a large internal reorganization energy associated with the reaction from 5 coordinate Fe(II) to 6 coordinate Fe(III). [Pg.161]

Perhaps two key points are emerging from the frenzied activity in protein electron transfer. First, it is clear that rapid electron transfer can occur over long distances in proteins. Furthermore, the rates of these reactions are generally consistent with expectations based on simple small molecule reactions. In particular it appears that proteins, like other polymers, may provide relatively high reorganization energies for electron transfer. [Pg.163]


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See also in sourсe #XX -- [ Pg.218 , Pg.219 , Pg.220 ]

See also in sourсe #XX -- [ Pg.218 , Pg.219 , Pg.220 ]




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