Redox enzymes and

MEmganese Redox Enzymes and Model Systems Properties, Structures, and Reactivity... 

Heering HA, Wiertz FGM, Dekker C, de Vries S. 2004. Direct immobilization of native yeast Iso-1 cytochrome c on bare gold Fast electron relay to redox enzymes and zeptomole protein-film voltammetry. J Am Chem Soc 126 11103-11112. 

Leger C, Elliott SJ, Hoke KR, Jeuken LJC, Jones AK, Armstrong FA. 2003. Enzyme electrokinetics Using protein film voltammetry to investigate redox enzymes and their mechanisms. Biochemistry 42 8653-8662. 

It has been said above that cyt c was one of the most important and extensively studied electron-transfer proteins with active heme centers. Thus, cyt c was widely used in enzyme-based biosensors and to study the mechanism of the catalytic process between redox enzyme and substrate. 

In most cases the electronic connection between an immobilized redox enzyme and the electrode requires a mediator to shuttle the electrons to the prosthetic group or some type of wiring that plays the same role. There are cases, however, especially those involving relatively small enzymes, where direct electron transfer takes place between the electrode and the prosthetic group or some electronic relay in the enzyme. Analysis of the catalysis responses then follows the principles described and illustrated in Section 4.3.2. Somewhat more complicated schemes are treated in references7, where illustrative experimental examples can also be found. 

Manganese Redox Enzymes and Model Systems Properties, Structures, and Reactivity Neil A. Law, M. Tyler Caudle, and Vincent L. Pecoraro... 

An excellent example of an innovative labeling strategy is provided by Willner and coworkers,94 who used Fc-conjugated uridine (dUTP) as electron transfer mediators between the redox enzymes and the electrode for the amplified bioelec -trocatalytic detection of viral DNA. 

The reconstitution of apo-enzymes on relay-cofactor monolayer-functionalized electrodes was used to align redox enzymes and to establish electrical contact... 

Copper Essential to all organisms constituent of redox enzymes and hemocyanin." Very toxic to most plants highly toxic to Invertebrates, moderately so to mammals. Pollution from industrial smoke and possibly from agricultural use. Wilson s disease, genetic recessive, results in toxic increase in copper storage. 

In principle, glucose oxidase could be oxidized directly at the electrode, which would be the ultimate electron acceptor. However, direct electron transfer between redox enzymes and electrodes is not possible because the FADH2/FAD redox centers are buried inside insulating protein chains (Heller, 1990). If it were not the case, various membrane redox enzymes with different standard potentials would equalize their potentials on contact, thus effectively shorting out the biological redox chains. The electron transfer rate is strongly dependent on the distance x between the electron donor and the electron acceptor. 

Biological and Biomimetic Catalysis of Manganese Redox Enzymes and Their Inorganic Models... 

A further approach to controlling electrical communication between redox proteins and their electrode support through a photo-command interface includes photo stimulated electrostatic control over the electrical contact between the redox enzyme and the electrode in the presence of a diffusional electron mediator (Scheme 12).[58] A mixed monolayer, consisting of the photoisomerizable thiolated nitrospiropyran units 30 and the semi-synthetic FAD cofactor 25, was assembled on an Au electrode. Apo-glucose oxidase was reconstituted onto the surface FAD sites to yield an aligned enzyme-layered electrode. The surface-reconstituted enzyme (2 x 10-12 mole cm-2) by itself lacked electrical communication with the electrode. In the presence of the positively charged, protonated diffusional electron mediator l-[l-(dimethylamino)ethyl]ferrocene 29, however, the bioelectrocatalytic functions of the enzyme-layered electrode could be activated and controlled by the photoisomerizable component co-immobilized in the monolayer assembly (Figure 12). In the... 

Likhtenstein, G.I., Redox Enzymes and Their Models, Pt. 1, Chemogolovka Nauka, Russia, 1982, p. 7 (in Russian). 

Artificial electron carriers are recognizable by the active sites of different redox enzymes and specifically biocatalysts containing Fe of Mo sulfur clusters as active sites. Bipyridinium radical cations, i.e. methyl viologen radical, MV+, exhibit proper electrical and size properties to penetrate into protein structures and to mediate reduction processes at the enzymes active sites. 

Inorganic NPs can be conjugated with important biomolecules such as redox enzymes and further act as nano-connectors that activate redox enzymes or electrical labels for biorecognition events. 

Potentiometric. Not all analytes can be readily assayed via a redox enzyme and in these instances the assay schemes suggest parameters other than electron transfer which may be probed. Indeed, even where a redox enzyme is available for the analyte in question, it is not always desirable to deploy an amperometric technique. 

During the last decade, immobilization of oxidase type enzymes by physical entrapment in conducting or ionic polymers has gained in interest, particularly in the biosensor field. This was related to the possibility for direct electron tranfer between the redox enzyme and the electroconducting polymers such as polypyrrole (1,2), poly-N-methyl pyrrole (3), polyindole (4) and polyaniline (5) or by the possibility to incorporate by ion-exchange in polymer such as Nafion (6) soluble redox mediators that can act as electron shuttle between the enzyme and the electrode. 

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