Redox sensor proteins

However, because of the mostly very slow electron transfer rate between the redox active protein and the anode, mediators have to be introduced to shuttle the electrons between the enzyme and the electrode effectively (indirect electrochemical procedure). As published in many papers, the direct electron transfer between the protein and an electrode can be accelerated by the application of promoters which are adsorbed at the electrode surface [27], However, this type of electrode modification, which is quite useful for analytical studies of the enzymes or for sensor applications is in most cases not stable and effective enough for long-term synthetic application. Therefore, soluble redox mediators such as ferrocene derivatives, quinoid compounds or other transition metal complexes are more appropriate for this purpose. 

RegB Histidine protein kinase Redox sensor RegB 37 53 Global regulation... 

Trx and Grx being the key redox sensors, their functions are modulated by ROS. While at a lower dose, ROS can induce their expression, thereby eliciting an adaptive response massive generation of ROS inactivates these proteins by posttranslational modifications (Kondo et al. 2006). In heart failure patients, a significant correlation between the serum concentration of Trx-1 and the severity of the disease has also been documented (Jekell et al. 2004). The increased Trx-1 activity is likely to be due to the adaptive response during the failure to compensate for the increased ROS activities. 

Lillig, C.H., Bemdt, C., Vergnolle, O., Lonn, M.E., Hudemann, C., Bill, E., and Holmgren, A. 2005. Characterization of human glutaredoxin 2 as iron-sulfur protein a possible role as redox sensor. Proc. Natl. Acad. Sci. USA 10 8168-8173. 

Fig. 1. Summary of avaiiabie knowiedge on the phototaxis signaiing pathways in H. sallnarum, R. sphaeroides, and H. halophila in a Che-iike reaction scheme. H. sali-narum contains the photoreceptors SRi and SRii, which are compiexed in the membrane to their signal transducers Htri and Htrii. These transducers modulate the autokinase activity of CheA and thus modulate the phosphorylation status of CheY. Phototaxis of R. sphaeroides proceeds via its photosynthetic reaction center (RC) and electron transfer chain (ETC) via a putative redox sensor. Positive phototaxis in H. halophila occurs via a similar pathway, while its negative phototaxis is triggered by photoactive yellow protein (PYP). The signal transduction pathway for PYP is unknown one candidate is the Che system. Possible adaptation mechanisms have been omitted from this figure.

For example, no cofactor has been found in the voltage sensor HERG (45). Flavin cofactors are boxmd to the NifL and Aer redox sensors (46-48). In plants, it is a flavin-mononucleotide-bound PAS in the NPHl protein that serves as a detector of blue hght, guiding phototropism (49,50). 

The topic of thin films, active coatings, sensor electrodes, and electrode modification for energy storage has been a very active branch of electrochemical research in the past [406 09]. Abundant examples are reported on this subject in the current literature [73], including immobilized redox-active proteins [410]. Therefore, this section cannot give a deep review on this topic, but will mainly emphasize the issues that are related to those addressed so far (Sect. 2.1). This section provides a possible starting point for entering this area of research more deeply. A discussion on thin films made of electrochemical polymerization of active monomers (e.g., aniline) will be only briefly covered here. Most products of these electrochemical... 

CV measurements showed that the reversible eleetrode reaetion of the [Fe(CN)6]" redox eouple was suppressed to some extent by the treatment with the DNA. The addition of the anti-DNA antibody further suppressed the redox reaetion thus decreasing the magnitudes of the CV peak currents. This is most likely caused by a steric hindrance of the bulky protein, which binds to the DNA double strands on the electrode surface, to mainly reduce the effective area of the electrode. The electrostatic repulsive effect may also contribute to the electrode response, since the isoelectric point of mouse IgM is commonly in the range of 4.5 to 7.0. Figure 11 shows the relationship between the decrease in the anodic peak current (A/p ) and the antibody concentration. As seen in this figure, the electrode system responded to the anti-DNA antibody in the concentration range of 1 — 100 nM. For the case of the mouse IgM, which does not interact with double-stranded DNA, the present system gave almost no response. The sensor did not respond to other serum proteins as well (data not shown). 

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