Conformational change, redox-induced

The ferro-complex CD spectrum shows that reduction of the heme iron alters the heme environment. Redox-induced protein conformation changes could alter the S5unmetry in the heme pocket or produce two binding modes for the reduced complex whose asymmetries nearly cancel each other. Redox-linked conformational changes are especially interesting in view of recent findings of oxido-reductase activity associated with the heme-hemopexin-receptor interaction (89). 

Nmr methods are also valuable in other areas of protein structure. For example, information about the role and extent of induced conformational changes (caused, for example, by inhibitor-substrate binding, by ionization of side chains, or by redox changes) can be obtained. 

In the X-ray structure of bovine heart cytochrome c oxidase in the fully oxidized state at 2.8 resolution, two hydrogen bond networks connecting the molecular surface on the matrix side to that on the intermembrane surface were identified (Tsukihara et ah, 1996). Both networks contain possible hydrogen bond structures, as defined by the criteria stated above, but do not include elements of structure comprising the O2 reduction site. However, small conformational changes induced by changes in the redox... 

Figure 33. Principle of operation for inducing ring rotation in a nonsymmetrical [2]catenate. Horizontal arrows represent redox processes, vertical arrows represent rearrangements. Cu" is a solid circle, whereas Cu is an open circle. The stable four-coordinate monovalent complex Cu (4) (top left) is oxidized to the intermediate tetrahedral divalent species Cu"(4j (top right) which rearranges to the stable five-coordinate Cu (5) complex, bottom right. Upon reduction, the five-coordinated monovalent Cu (s) is formed (bottom left) which finally undergoes conformational changes to restore the starting Cu (4) (top left).

The direct detection of DNA via conformational changes of ferrocene-conjugated DNA stem-loop (or hair-pin) structure onto electrode surface induced by the hybridization was also proposed (Fig. 11.1c) [4, 20]. The conformational change induces the displacement of ferrocene molecules from the electrode surface, resulting in a drop in peak redox current measured by cyclic voltametry. The detection limits were 115 fM for 24-base oligonucleotide [20] and 10 pM for 17-base oligonucleotide [4], respectively. Furthermore, the difference between... 

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