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Papain (EC2.22.4.3) is a thiol protease with high level of activity that has widespread industrial applications. The use of immobilized papain provides many advantages over its free form. In many applications, cysteine must be added as an activator. On the other hand, certain bivalent metal ions including Ca²⁺ behave as the inhibitors of papaein. In the present study, after preparation of Sepharose 6B with CNBr, a 5 mg/ml-protein solution was added to activate the gel for covalent attachment of enzyme and, subsequently, 2M glycine solution was added to block the remaining active groups on the gel.  The immobilization process brought about significant enhancement of storage, thermal stability, stability at extreme pHs, and resistance against the inhibitory effect of bivalent metal ions with respect to papain. The optimum temperature of papain was increased by 20 °C (from 60 to 80 °C) and its optimum pH was shifted from 7 to 8.0 upon immobilization. Also k_m and k_cat of the enzyme altered due to the immobilization process.These results are important in particular if one considers that the major problem in enzyme immobilization is the loss of enzyme activity and catalytic efficiency.

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Aims: Peroxidases are used in a wide range of biotechnological processes, most of which are carried out at high temperatures and high pH levels. Since most of the commonly used peroxidases are unstable and inactive in alkaline conditions and high temprature, it is necessary to find thermoalkalophilic peroxidases for practical purposes.
Materials and Methods: In this study, extracellular production of peroxidase in the native strain Bacillus tequilensis was studied. for this purpose, Enzyme activity was evaluated using two substrates 2,4-DCP and pyrogallol in bacterial liquid culture and the effect of culture time on enzyme production, as well as the effect of parameters such as pH and temperature on enzyme activity investigated. The relative purification of the enzyme was performed using ion exchange chromatography with sephadex DEAE A50 and the kinetic parameters of enzyme activity were evaluated. In this study, kinetic parameters such as Km and Vmax were calculated.
Results: Measurement of enzyme activity at different times of culture indicated that the highest amount of peroxidase production was obtained 72 h after bacterial culture.

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Application of chemical pesticides has increased significantly worldwide and has raised serious concerns about environmental pollutions. One of the encouraging trends to minimize pesticide risk is production of resistant plants containing toxic proteins against insect pests. Considering the importance of purification and characterization of digestive enzymes in the production of resistant plants, in this study an α-glucosidase from the Naranga aenescens Moore's midgut was purified by ammonium sulfate precipitation, ion exchange chromatography on DEAE-sepharose, and concentrating through ultrafiltration. The apparent molecular mass of the enzyme was 48 kDa determined by SDS-PAGE. The optimum pH and temperature of the enzyme were 6.0 and 45°C, respectively. The irreversible thermoinactivation of the enzyme showed that it was highly stable at 35ºC but moderately stable at 40 and 45ºC. Zn²⁺, Hg²⁺, Co²⁺ at 10 and 20 mM, and Ba⁺²only in 20 mM strongly inhibited the α-glucosidase activity. Ba²⁺ and Ca²⁺ only at 10 mM, EDTA and Hg₂²⁺ only at 20 mM and Mg²⁺ at 10 and 20 mM significantly increased the enzyme activity. The K_m and K_cat values for the α-glucosidase were 0.54 mM and 3.62 min^-1, respectively, when p-Nitrophenyl-α-D-glucopyranoside (pNαG) was used as a substrate.