Redox sensitivity

NifA proteins are of one of two types. One group consists of 02-sensitive NifA proteins, which are found in the rhizobia Bhodobacter and Ae spirillum. These proteins have a proposed iron-binding motif on a linker between the central and C-terminal domains that may form a redox-sensitive... 

Coleman, A. S. and Holland, H. D. (in press, January 2000). The global diagenetic flux of phosphorus from marine sediments to the oceans redox sensitivity and the control of atmospheric oxygen levels. In "Marine Authigenesis from Microbial to Global" (C. R. Glenn, L. Prevot-Lucas and J. Lucas, eds), SEPM Publication No. 66. 

It is possible that dietary flavonoids participate in the regulation of cellular function independent of their antioxidant properties. Other non-antioxidant direct effects reported include inhibition of prooxidant enzymes (xanthine oxidase, NAD(P)H oxidase, lipoxygenases), induction of antioxidant enzymes (superoxide dismutase, gluthathione peroxidase, glutathione S-transferase), and inhibition of redox-sensitive transcription factors. 

Redox-sensitive resin 24 designed for solid-phase peptide synthesis (SPPS) [29] was prepared from commercially available 2,5-dimethylben-zoquinone in seven steps [30] and loaded to a support via a Wittig reaction. Release of the peptide occurs using two sequential mild conditions, reduction with NaBH4 followed by TBAF-catalyzed cyclic ether formation (Scheme 8) which provide orthogonality to acid sensitive reactions. 

OH redox-sensitive resin linker W (29) 0 x COOH NaBH , then TBAF COOH... 

Zheng A, Shan D, Wang B. A redox-sensitive resin linker for the solid... 

As already mentioned, van Kuijk and colleagues (Kalariya et al., 2008) tested the effects of oxidation products of [i-carotcnc, lutein, and zeaxanthin on the activation of redox-sensitive transcription factors, NF-kB, and AP-1 in cultured ARPE-19 cells. Degradation products of all three carotenoids induced activation of NF-kB and AP-1, and these effects were ameliorated by pretreatment of cells with 1 mM NAC. NF-kB is a major transcription factor that binds to promoter sites of many pro-inflammatory cytokines such as IL-1, IL-6, TNF-a, and iNOS. These results indicate that the degradation products of carotenoids can stimulate a pro-inflammatory pathway. 

In summary, the apparent redox modulation of lycopene certainly affects two important redox sensitive transcription factors at higher concentrations of lycopene. However, electrophilic lycopene oxidation products cannot be ruled out as the major activators and the activation may be due to specific molecular interactions. 

Hanson GT, Aggeler R, Oglesbee D, Cannon M, Capaldi RA, Tsien RY, Remington SJ (2004) Investigating mitochondrial redox potential with redox-sensitive green fluorescent protein indicators. I Biol Chem 279 13044—13053... 

A. Lewenstam, J. Bobacka, and A. Ivaska, Mechanism of ionic and redox sensitivity of p-type conducting polymers. 1. Theory. J. Electroanal. Chem. 368, 23—31 (1994). 

Intracellular and extracellular ROS activate tyrosine and serine-threonine kinases (i.e., the MAPK family members). Following TNF-a, TGF-f5 or EGF stimulation, intracellular ROS are generated which stimulate various signaling pathways [73], Tyrosine kinase receptors (e.g., EGF, PDGF and TGF-a) may be activated by ROS directly via protein sulfhydryl group modifications, or inhibition of phosphotyrosine phosphatases (PTPases) and subsequent receptor activation. The latter is possible as PTPases contain a redox-sensitive cysteine at their active site [78], and oxidation of protein sulfhydryl groups results in the inactivation of PTPases. 

Fig. 3. Sample collection deeper into the saturated zone results in more reducing conditions (a) and increase in redox sensitive elements such as Fe (b).

The isotope geochemistry of two redox-sensitive elements, Cr and Se, are compared in Chapter 9 by Johnson and Sullen (2004). Because Cr(VI) is quite soluble in natural waters, and is highly toxic, the signiflcant fractionation in ratios that occurs during redox... 

Morford JL, Emerson S (1999) The geochemistry of redox sensitive trace metals in sediments. Geochim Cosmochim Acta 63 1735-1750... 

Yarincik KM, Murray RW, Lyons TW, Peterson LC, Haug GH (2000) Oxygenation history of bottom waters in the Cariaco Basin, Venezuela, over the past 578,000 years Results from redox-sensitive metals (Mo, V, Mn, and Fe). Paleoceanogr 15 593-604... 

Micromolar quantities of RNS are generated primarily by nitric oxide synthase 2 (NOS2), an enzyme that is up-regulated during colon-cancer progression. As discussed below, deoxycholate (DOC), a hydrophobic secondary bile acid, activates the redox-sensitive transcription factor NF-kB, resulting in increased levels of NOS2 and enhanced S-nitrosylation of proteins. Additional sources of bile-acid-induced ROS and RNS are also likely. ... 

Uranium is a redox sensitive element, with most naturaiiy occurring uranium either as or Theory wouid indicate that U shouid be preferentiaiiy retained in oxidized phases, such as dissoived whereas shouid be preferentiaiiy... 

FIGURE 2.11 Example of biplot. The scores (filled symbols) are replicates of analyses of wine samples of three vintages (2004, 2005, and 2006, respectively), while the loadings (stars) represent the potentiometric sensors used for the measurements (A = anion-sensitive sensors, C = cation-sensitive sensors, G = redox-sensitive sensors, pH = pH sensor) (reproduced from Rudnitskaya etal. 2009b, with permission). 

An interesting synthetic approach was introduced by Ito et al. [99], They covalently bound an azoinitiator, 4,4 -azobis(4-cyanovaleric acid) to trypsin. In the presence of the monomers, 3-carbamoyl-1 -(p-vinylbenzyl)pyridinium chloride, or a mixture of methacrylic acid and methyl methacrylate, trypsin-polymer conjugates were synthesized (Fig. 3) which were sensitive to external signals, i.e., redox sensitive and pH sensitive, respectively. 

Runde, W., Conradson, S. D. Efurd, D. W., Lu, N VanPelt, C. E. Tait, C. D. 2002. Solubility and soiption of redox sensitive radionuclides (Np,Pu) in J-13 water from the Yucca Mountain site comparison between experiment and theory. Applied Geochemistry, 17, 837-853. 

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