Peroxidases action mechanism

Action mechanisms and kinetic features of catalases, peroxidases and monooxygenases. Catalytic system selection for conjugated dehydrogenation, epoxidation and monooxygenation reactions. 

These studies simulate several of the most important functions of redox enzymes (catalases, peroxidases and monooxygenases) develop their biological simulators and explain some aspects of the action mechanism of these enzymes. 

Critically analyzing the mechanism (6.8)-(6.12), one may note the unsuitability of the currently presented interaction between complexes E-Fe3+—OH and E-Fe3+ OOH and substrates (H202 and H2D), because it is unclear how the substrate is activated. Moreover, intensification of the catalase reaction induces a non-classical peroxidase activity increase in ethanol and formic acid oxidation reactions. This indicates the existence of a unit common to these two processes [82, 83], The alternative action of catalase (catalase of peroxidase reaction) in the biosystem with solidarity of elementary stage mechanisms should be noted [88, 89], Peroxidase action of catalase requires a continuous supply of H202 for ethanol and formic acid oxidation, which can be explained by oxidation according to conjugated mechanism [90],... 

Kawano T, Muto S. Mechanism of peroxidase actions for salicylic acid-induced generation of active oxygen species and an increase in cytosolic calcium in tobacco suspension culture. J Experi Bot2000 51 685-693. 

These experiments suggest that the secondary complexes should no longer be regarded as Michaelis-Menten enzyme substrate complexes but as reaction intermediates in the same sense that free radicals and semi-quinones are reaction intermediates, for all three classes of compounds provide a path for stepwise reactions. As a consequence the accepted mechanism for peroxidase action needs revision. 

This mechanism represents peroxidase action and the peroxidatic activity of catalase. 

Garlic s proven mechanisms of action include (a) inhibition of platelet function, (b) increased levels of two antioxidant enzymes, catalase and glutathione peroxidase, and (c) inhibition of thiol enzymes such as coenzyme A and HMG coenzyme A reductase. Garlic s anti-hyperlipidemic effects are believed to be in part due to the HMG coenzyme A reductase inhibition since prescription medications for hyperlipidemia have that mechanism of action (statins). It is unknown whether garlic would have the same drug interactions, side effects, and need for precautions as the statins. 

Peroxidase activity has long been associated with extracts of plant tissue and the crystalline enzyme from horse radish root has been studied in extenso, particularly in regard to its mechanism of action (11). Plants also contain ferredoxin and various specialized cytochromes, both of which substances play an essential role in photosynthesis (95, 96). Agavain, a crystalline proteolytic enzyme from the leaves of Agave,... 

Anni H, Yonetani T (1992) Mechanism of action of peroxidases. In Sigel H, Sigel (eds) A Metal ions in biological systems degradation of environmental pollutants by microorganisms and their metalloenzymes. Marcel Dekker, New York, p 219 Oritz de Montellano PR (1992) Annu Rev Pharmacol Toxicol 32 89 van Deurzen MP), van Rantwijk F, Sheldon RA (1997) Tetrahedron 53 13,183 Whitaker JR (1972) Principles of enzymology for the food sciences. Marcel Dekker, New York, p 591... 

Larkin injected several peroxidases at 0.1-10 ppm into one-half of a tobacco leaf and found some protection. He suggested that peroxidase, which is often associated with plant stress conditions, may be important in physiologic resistance. It is doubtful that any one mechanism of action exists. It is important that we understand the mechanism of ozone injury and resistance in plants, so that we can determine better what chemicals may play a role in protecting plants against oxidants. 

The available agents with antithyroid activity are the thioamides propylthiouracil, carbimazole and methimazole also known as thiamazole. Their thio-carbamide group is indispensable for antithyroid activity. The mechanism of action is complex. The most important action is the prevention of hormone synthesis by an inhibition of the thyroid peroxidase-catalyzed reactions involved in iodine organification. These agents also block the coupling of the iodoty-rosines. 

Isoniazid (INH) is a synthetic derivative of isonico-tinic acid. It has bactericidal activity against both intra- and extra-cellular mycobacteria. It also displays anti-bacterial activity in caseous lesions, but only in proliferating cells. Losing genes which code for catalase and peroxidase is the major mechanism through which resistance occurs. Single mutations can rapidly result in such resistance if isoniazid is used alone. Its mechanism of action is presumably based on inhibition of the synthesis of mycolic acids, unique and essential components of the mycobacterial cell wall. 

NADH peroxidase (p. 857, Eq. 15-59) does not contain a transition metal ion. Propose a reasonable detailed mechanism for its action and compare it with mechanisms of action of heme peroxidases. 

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