Cytochrome -c Is A Tunnel Protien

Time (minutes)

FIGURE 26.5 Same conditions as Figures 26.3 and 26.4 except assay done 1 h after Figure 26.4.

FIGURE 26.6 (a) Diagram depicts some of the possible pathways of nuclear factor kappa B, which controls NF-k-B binding sites on promoters belonging to several key inflammatory cytokines and growth factors involved in the inflammatory process.

FIGURE 26.6 (a) Diagram depicts some of the possible pathways of nuclear factor kappa B, which controls NF-k-B binding sites on promoters belonging to several key inflammatory cytokines and growth factors involved in the inflammatory process.

bound in the membrane of phagocytic cells and are gp 91phox and p22-phox. When the enzyme is activated it is believed that various protien such as p40, p67, p47 Rap 1A, and p2/rac1/2 migrate to the membrane and attach in the manner shown in the diagram. An electron from the cofactor NADPH is trasferred to oxygen and NADP+ and H+ are produced. When this electron is transferred to molecular oxygen, it produces the free radical superoxide anion (O-). This avidly reacts with the free radical nitric oxide and produces peroxynitrite. If luminol is added the peroxynitrite or its carbon dioxide derivative reacts to produce blue light at 425 nm. It is known that the free radicals (NO and O-) have a high attraction for each other and, if found in sufficient quantity, they will produce substantial amounts of OONO- (Figure 26.7). This strong oxidant, peroxynitrite, attacks all the major biochemical entities, namely, carbohydrates, lipids, proteins, enzymes, and nucleic acids DNA and RNA.

Some antioxidants are quickly attacked by peroxynitrite such as sulfhydryl-containing compounds and mono-, di-, tri-, and polyphenols.14 These compounds protect against peroxynitrite attack by destroying it, and enhanced luminescence is inhibited, which allows one to measure the effects of these antioxidants easily with fewer cells and in real time. Recently, it has been shown that peroxynitrite reacts with carbon dioxide and the compound that results from this interaction can react with luminol. Whether the luminol reacts directly with peroxynitrite or the carbon dioxide derivative, CL or light results.

plasma membrane plasma membrane

In unstimulated cells, the oxidase is inactive, consisting of membrane-bound p22-phox and gp91-phox. Oxidase function requires translocation of additional proteins to die membrane components to form the NADPH oxidase, and generate superoxide.

Stimulation results in translocation of cytosolicphox proteins, p47, p67 and p40, and the G proteins p21racI/2 and possibly RaplA, which forms the competent NADPH oxidase. The oxidation of NADPH generates an electron which is shuttled through the FAD-containing flavoprotein portion of the oxidase to the cytochrome b to generate superoxide, and a proton is pumped through the associated proton channel.

FIGURE 26.6 (Continued) (b) Diagram of NADPH oxidase (in active and inactive states).

Inducible NO synthase l-Arg l-Arg l-Cit r l-Cit

DNA damage

(deamination, nicks, strandbreaks)

PARS activation

Nitration or oxidation of guanine (DNA)

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