Introduction: Peroxidase (POD) is an important antioxidant enzyme that catalyzes oxidation of a number of organic and non-organic substrates using hydrogen peroxide as the electron acceptor. At physiological low levels, reactive oxygen species (ROS) can act as redox messengers in the regulation of intracellular signaling. However, in excess amounts they can suppress the immune system and cause oxidative stress. Considering the high consumption of tea and coffee as the most common drink in the world, in the present study the effect of caffeine and theophylline on the activity of POD has been investigated. Materials and Methods: The activity of POD was measured by following absorption at 510 nm due to the oxidation of 4-aminoantipyrine in the absence and presence of caffeine and theophylline. The enzyme kinetic parameters were then measured and compared in each case. Results: It was shown that both methylxanthines acted as inhibitors with IC50, the amount of inhibitor to reduce the enzyme activity by 50%, of 0. 6 and mM 0. 55 mM for caffeine and theophylline respectively. The kinetic constants, Km and Vmax, indicated that both inhibitors worked by an un-competitive mechanism on POD activity. The values of Ki were calculated as 0. 08 and 0. 045 mM for caffeine and theophylline respectively. Conclusions: Lower values of IC50 and Ki for theophylline compared to caffeine, led us to a final conclusion that theophylline is a stronger inhibitor of POD than caffeine.

Horseradish Peroxidase was successfully encapsulated in calcium alginate for phenol removal. The optimum gelation condition was found to be 0.75%w/v of sodium alginate solution and 4.5% w/v of calcium chloride hexahydrate. Upon immobilization, the pH profile of enzyme activity changed as it showed a higher relative value in basic and acidic solutions. It was also observed that enzyme activity retention of encapsulated HRP was independent of enzyme concentration. Besides, for each phenol concentration, there would be an enzyme concentration beyond which it had no significant effect on phenol removal. Investigation of phenol removal with time for both encapsulated and free enzymes showed that the encapsulated enzyme had a lower efficiency compared to the same concentration of the free enzyme; however, the capsules were reusable up to four cycles without any changes in their retention activity. The optimum ratio of hydrogen peroxide/phenol was found to depend on phenol concentration and that it varied from 0.94 to 1.15 for phenol concentrations between 2-10 mM.

Introduction: Monoclonal antibody has many applications against Peroxidase among which Peroxidase-anti Peroxidase (PAP) complex formation is of great importance. This complex is used in many immunohistochemical and immunocytochemical staining techniques. The aim of this study was the production of a mouse antiPeroxidase of hybridoma cell line to be used in Peroxidase - anti Peroxidase immunostaining.Materials & Methods: The Balblc mice were first immunized by repeated injections of horseradish Peroxidase (HRP). After the confirmation of their immunization by ELISA, the spleen lymphocytes and SP2/0 myeloma cells were hybridized by using PEG. The hybridoma cells were then selected through the selective HAT medium. From seven rounds of cell fusion, 224 hybridoma clones were obtained, from which six clones produced monoclonal antibody against HRP. Once again from these six clones, two clones were selected and developed. Limiting dilution was performed twice and monospecific clones were developed.Results: Using the Isostrip kit revealed that both monoclonal anti Peroxidase antibodies (P1F11D2, P2F6F3) were from lgG1 isotype class. In addition, ELISA test showed that the monoclonal antibodies don't affect the active site of the enzyme. Therefore it seems that the produced antibodies are suitable for formation of PAP immune complex.Conclusion: At present, this study is being carried out farther to produce PAP complex and investigate its practical usage in immunohistochemical and immunocyto chemical techniques.

Objective: To cease the increasing damage to the brain neurons following epileptic seizures, natural anti-oxidative systems play the main role. One of the most important detoxifying systems is composed of the trace element selenium and its dependent detoxifying enzyme, glutathione Peroxidase. The object of this study was to evaluate serum selenium and red blood cell glutathione Peroxidase activity in pediatric epileptics and compare it with that of healthy children. Material & Methods: Patients suffering from various types of epilepsy were studied during a 15-month period. Control group consisted of healthy children with no history of any neurologic disease. Serum selenium level and RBC Glutathione Peroxidase activity was evaluated and the results compared. Findings: Fifty three epileptic patients with a mean age of 5.5 years and 57 healthy children with a mean age of 5.6 years were enrolled in this study. Statistically significant differences in the mean values for serum selenium level (72.9 vs. 86.0 ng/ml, P=0.017) and also RBC glutathione Peroxidase activity (440.6 vs. 801.0 nmol/min/ml, P=0.000) between the two groups were observed. On the other hand, after analyzing the study results, trying to introduce a value for GPx activity, which could be accepted as a reliable indicator for serum selenium deficiency in patients, was not successful.Conclusion: Findings of the present study strongly support the proposed crucial role for the trace element selenium and deficiency of its dependent enzyme, glutathione Peroxidase, in epilepsy pathogenesis.