Metalloproteins table electron transfer

Rate Constants and Reactivity. Electron-transfer reactions of plastocyanin (and other metalloproteins) are so efficient that only a narrow range of redox partners (having small driving force) can be employed. Rates are invariably in the stopped-flow range, Table I. Unless otherwise stated parsley plastocyanin... 

Table 10. A comparison of rate constants for intramolecular electron transfer in Ru(NH3)j-modiiied electron transport metalloproteins, modifications at surface histidine present in native proteins, pH 7. Values of AE° by determined measurements on modified protein except as indicated...

Table 5.12 Intramolecular Electron Transfer Rate Constants in Metalloproteins at 25°C...

Kinetic data for electron transfer between two metalloproteins are presented in Table V. The rate constants and activation parameters for the Ps(II)-Ps(III) and Az(I)-Az(II) exchange reactions were calculated from the kinetic data for the first three reactions (for which K 1, AH° 0, AS° 0 in addition, the rate constant for the Hh(II)-Ps(III) reaction is independent of ionic strength (31)). The calculated exchange data were then used to predict the kinetic parameters for the Ps(II)-Az(II) reaction. As is evident from Table V, the agreement of the observed and predicted parameters is satisfactory, particularly since the Ps( II )-Az( II) reaction has a relatively complex mechanism (57) involving conformational changes on both Ps(III) and Az(I). 

Table III summarizes rate, helicity, and donor-acceptor distance data for the 16-mer bundle. Because of the observable trend in conformation versus rate in the electron transfer studies, it was decided to measure donor-acceptor distances in the 16-mer metalloprotein bundles. In order to study the effects of solution conditions on H, the donor-acceptor distance, Forster energy transfer was used as a spectroscopic ruler, according to...

Table 24 Binding Constants ) and Electron Transfer Rates (k ) for Oxidation of Some Cu Metalloproteins ...

Table 2.3. Intramolecular Electron Transfer Reactions Involving Metalloproteins at 25 °C ... 

In many biological systems electron transfer occurs over large distances between prosthetic groups located in membranes and proteins. The electron transfer takes place over distances of about 1 nm. Electron transfer reactions and their pathways in a metalloprotein are complex in nature. The reactive centres in the protein are surrounded by polypeptide chains which separate redox sites from each other [17]. In many proteins the prosthetic groups usually contain one or more metal ions (Fe, Cu etc) separated by polypeptide chains [18] and the reactions are usually second order. Electron transfer reactions within polypeptides are surprisingly fast even over long distances, as can be seen fom the results given in Table 6.3. 

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