Horseradish peroxidase reactivity

Rodrfguez-Lopez, J.N., Gilabert, M.A., Tudela, J., Thorneley, R.N.R, and Garcfa-Canovas, R, Reactivity of horseradish peroxidase compound II toward substrates kinetic evidence for a two-step mechanism,... 

The rate constants of kn and kx obtained using Eq. (24) reveal that (i) the activity of Fem-TAMLs in bleaching Safranine O (k ) increases more than 10-fold when the tail ethyl groups of la are replaced by fluorine atoms in lk. The rate constant kn for lk equals l(rM 1s 1 at 25°C, a value that corresponds to those found for the reactivity of horseradish peroxidase Compound II... 

The reactivity of compounds such as 28 was clearly demonstrated by the peroxidase-catalyzed covalent binding of A -methyW-hydroxyellipticine (27) to proteins (756). Using horseradish peroxidase and hydrogen peroxide, tritiated-27 was converted to the 9-oxoellipticine derivative in the presence of bovine serum albumin (BSA) and human antibovine IgG in vitro. Covalent binding to these proteins was confirmed by gel electrophoresis, combustion, and liquid scintillation analysis. Dissolution of the BSA-ellipticinium derivative with pronase and... 

Figure 5.11. Reactive oxidant production by human neutrophils. In (a), neutrophils (5 x lOVml) were suspended in buffer containing 10 pM luminol in the presence and absence of a mixture of the extracellular oxidants scavengers SOD (1 /ig/ml), catalase (2 pg/ml) and methionine (0.25 mg/ml, to scavenge HOC1). In (b), neutrophils (1 x 106/ml) were suspended in buffer containing 75 jUM cytochrome c (to measure Of production) or 4 jUM scopoletin plus 5 /ig/ml horseradish peroxidase (to measure H202 production). In (c), neutrophils (2 x lOfyml) were placed in the chamber of a Clark-type 02 electrode. All measurements were made at 37 °C cell suspensions were stimulated by the addition of 1 /

Poulsen AK, Scharff-Poulsen AM, Olsen LF (2007) Horseradish peroxidase embedded in polyacrylamide nanoparticles enables optical detection of reactive oxygen species. Anal Biochem 366 29-36... 

A number of NO-derived reactive species can initiate lipid peroxidation, including nitrogen dioxide and, most notably, ONOO , which displays unique properties as a mediator of lipid oxidation. On a molecular basis, ONOO is a more potent lipid oxidant than hydrogen peroxide and, unlike H2O2, it does not require metal catalysis. The one-electron oxidants such as metals, as well as heme proteins and peroxynitrite, are assumed to play an important role in many diseases associated with oxidative stress. Heme proteins such as horseradish peroxidase (HRP) can produce alkylperoxyl radicals through two sequential... 

The present volume is a non-thematic issue and includes seven contributions. The first chapter byAndreja Bakac presents a detailed account of the activation of dioxygen by transition metal complexes and the important role of atom transfer and free radical chemistry in aqueous solution. The second contribution comes from Jose Olabe, an expert in the field of pentacyanoferrate complexes, in which he describes the redox reactivity of coordinated ligands in such complexes. The third chapter deals with the activation of carbon dioxide and carbonato complexes as models for carbonic anhydrase, and comes from Anadi Dash and collaborators. This is followed by a contribution from Sasha Ryabov on the transition metal chemistry of glucose oxidase, horseradish peroxidase and related enzymes. In chapter five Alexandra Masarwa and Dan Meyerstein present a detailed report on the properties of transition metal complexes containing metal-carbon bonds in aqueous solution. Ivana Ivanovic and Katarina Andjelkovic describe the importance of hepta-coordination in complexes of 3d transition metals in the subsequent contribution. The final chapter by Sally Brooker and co-workers is devoted to the application of lanthanide complexes as luminescent biolabels, an exciting new area of development. 

The rates of asymmetric sulfoxidation of thioanisole in nearly anhydrous (99.7%) isopropyl alcohol and methanol catalyzed by horseradish peroxidase (HRP) were determined to be tens to hundreds of times faster than in water under otherwise identical conditions (Dai, 2000). Similar effects were observed with other hemo-proteins. This dramatic activation is due to a much higher substrate solubility in organic solvents than in water and occurs even though the intrinsic reactivity of HRP in isopropyl alcohol and in methanol is hundreds of times lower than in water. In addition, the rates of spontaneous oxidation of the model prochiral substrate thioanisole in several organic solvents was observed to be some 100- to 1000-fold slower than in water. This renders peroxidase-catalyzed asymmetric sulf-oxidations synthetically attractive. 

Kubow S, Wells P. In vitro bioactivation of phenytoin to a reactive free radical intermediate by prostaglandin synthase, horseradish peroxidase and thyroid peroxidase. Mol Pharmacol 1989 35 1-8. 

Ator MA, Ortiz de Montellano PR. Protein control of prosthetic heme reactivity reaction of substrates with the heme edge of horseradish peroxidase. J Biol Chem 1987 262(4) 1542-1551. 

Matsuo T, Murata D, Hisaeda Y, Hori H, Hayashi T (2007) Porphyrinoid chemistry in hemoprotein matrix detection and reactivities of iron(IV)-oxo species of porphycene incorporated into horseradish peroxidase. J Am Chem Soc 129 12906-12907... 

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