2010
DOI: 10.1007/978-1-59745-364-6_6
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Peroxidase Active Site Activity Assay

Abstract: Cyclooxygenase enzymes house spatially distinct cyclooxygenase- and peroxidase-active sites. The two-electron reduction of peroxides to their corresponding alcohols by the heme bound in the peroxidase-active site converts the heme to a ferryloxoprotoporyphrin cation radical, with a reductant providing the two electrons necessary to bring the heme back to its resting state. The ferryloxoprotoporyphrin cation radical can abstract a hydrogen atom from a tyrosine residue in the cyclooxygenase-active site, activati… Show more

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Cited by 5 publications
(6 citation statements)
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“…Table 10 shows that the 1% rice hull extract also induced a decrease in the enzyme myeloperoxidase, a representative neutrophil biomarker, in the mouse ear tissues from 270.81 U to 95.32 U, or a 65.62% reduction. The extent of decrease in this inflammation-associated enzyme 38 is similar to the above-mentioned three biomarkers. It is, therefore, likely that the inhibitory effect against myeloperoxidase is mechanistically related to the corresponding effects on the biomarkers.…”
Section: ' Results and Discussionsupporting
confidence: 75%
“…Table 10 shows that the 1% rice hull extract also induced a decrease in the enzyme myeloperoxidase, a representative neutrophil biomarker, in the mouse ear tissues from 270.81 U to 95.32 U, or a 65.62% reduction. The extent of decrease in this inflammation-associated enzyme 38 is similar to the above-mentioned three biomarkers. It is, therefore, likely that the inhibitory effect against myeloperoxidase is mechanistically related to the corresponding effects on the biomarkers.…”
Section: ' Results and Discussionsupporting
confidence: 75%
“…Values for the peroxidase activity of Fg-cat are directly comparable to the reported peroxidase activity of mammalian cyclooxygenase enzymes in oxidation of ABTS [29]: with COX-1 and COX-2 using 15 S -HPETE as the oxidizing co-substrate, the enzymes exhibit turnover numbers of 51 – 120 s −1 , a Km for 15-HPETE of 8.5 – 9.9 μM, and kcat/Km values of 6 – 12 μM −1 .s −1 [29]. In comparison, the kcat/Km for Fg-cat in oxidizing ABTS using 13-HPOTE as co-substrate gave the slightly higher value of 22 μM −1 .s −1 (Figure 8).…”
Section: Discussionsupporting
confidence: 70%
“…This reduction occurs at the expense of oxidation of one of endogenous amino-acid residues (eg, tyrosine residues of cyt c) [13]. Compound II drives the oxygenase half-reaction of the cycle leading to a protein radical-driven hydrogen abstraction from a substrate, formation of a carbon-centered lipid radical and, upon addition of molecular oxygen, a peroxyl radical and an oxygenated product [14]. Our previous work indicates that tyrosyl radicals (Tyr•) are likely candidates for this role in cyt c/CL catalyzed peroxidation of polyunsaturated CLs [15] and abstraction of hydrogen from hydroxy-groups of phenolic compounds (eg, etoposide) [11].…”
Section: Introductionmentioning
confidence: 99%