Soybean peroxidase, hydrogen peroxide

Isoflavones have been implicated in goiter induction. Soybean extracts inhibit reactions catalyzed by thyroid peroxidase (TPO), essential to the synthesis of thyroid hormones (Divi et al., 1997). Genistein and daidzein (at about 1-10 p,M of IC50) may act as alternative substrates for tyrosine iodination (Divi et al., 1997). Furthermore, genistein and daidzein have also been shown to cause the irreversible inactivation of TPO in the presence of hydrogen peroxide. Genistein also inhibits thyroxine synthesis in the presence of iodinated... 

B. Wang, B. Li, Z. Wang, G. Xu, Q. Wang, and S. Dong, Sol-gel thin-film immobilized soybean peroxidase biosensor for the amperometric determination of hydrogen peroxide in acid medium. Anal. Chem. 71, 1935-1939 (1999). 

The LbL methods have been also used to prepare spatially ordered bienzymatic electrodes, two examples are shown in Figure 2.25. In the first one, glucose is aerobically oxidized by GOx in the outer layers to produce hydrogen peroxide that is thereafter reduced by soybean peroxidase (SBP) wired to the electrode with PAH-Os [182]. This system responds both to H2O2 and to glucose, but in the... 

Figure 4 pH dependence of the catalytic activities of soybean peroxidase (SBP) and HRP. Activities were measured using an assay consisting of 2.0 mM phenol, 2.4 mM 4-aminoantipyrine, and 0.2 mM hydrogen peroxide buffered to the desired pH. (Adapted from Refs. 9 and 90.)... 

Bodalo A, Gomez JL, Gomez E et al (2006) Removal of 4-chlorophenol by soybean peroxidase and hydrogen peroxide in a discontinuous tank reactor. Desalination 195 51-59... 

Gomez JL, Bodalo A, Gomez E et al (2008) A transient design model of a continuous tank reactor for removing phenol with immobilized soybean peroxidase and hydrogen peroxide. Chem Eng J 145 142-148... 

Hydrogen peroxide can be used with molybdenum and tungsten catalysts to provide a convenient source of bromine in situ from bromide ion.226 This mimics the action of haloperoxidase enzymes. It provides a less hazardous way to use bromine. Soybean peroxidase can be used with hydrogen peroxide to oxidize alcohols to aldehydes and ketones.227 The use of hydrogen peroxide with an immobilized lipase has allowed the oxidation of linoleic acid to a monoepoxide in 91% yield. The enzyme could be reused 15 times.228 Indole has been oxidized to oxindole in 95% yield using hydrogen peroxide with a chloroperoxi-dase (4.48a).229... 

Khmelnitsky and coworkers recently reported a rather unusual application of soybean peroxidase. In the presence of nitrite and hydrogen peroxide, phenols are nitrated. The nitration of tyrosine has been reported earlier152, 531. The substrate spectrum was enlarged by various phenolic compounds (Table 16.3-9). Thus, such an enzymatic nitration represents an alternative to chemical nitration (especially for acid-labile phenols, which cannot by nitrated chemically). 

Figure 9 The increase in the catalytic hydrogen peroxide electroreduction current upon adding the soybean peroxidase-labeled target in microelectrodes loaded with different amounts of the probe oligonucleotide. The probe was deposited for (a) 1 minute, (b) 2.5 minutes, (c) 5 minutes, and (d) 10 minutes.

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