The study included partially purified of polyamine oxidase (PAO) from sheep's brain tissue by dialysis and ion exchange chromatography using DEAEcellulose techniques. Tow isoenzymes (I،II) were obtained with specific activities 3.876 and 2.856 units/ mg of protein and purification folds 11, 8 times respectively compared with crude enzyme. The specific activity of PAO I was better than PAO II, thus we considered it for following studying. The optimal condition showed 100 μL volume of enzyme, pH=9, 40ͦ C, at incubation time 10 min. Some of properties of partially purified PAO enzyme were studied and the specificity was found to be superior to the base material, where it was given the highest activity when using spermidine. Using lineweaver_ Burk plot, the values of maximum velocity (Vmax) and Michaelis constant (Km) were found to be 0.145 Unit/ ml and 43.4 mM respectively, and potassium ion was the most activator ion to the enzyme arrived to 233.8%. The compounds (ammonium chloride, sodium fluoride, phenyl hydrazine, sodium azide and EDTA) showed a significant inhibitory effect on the activity of the enzyme (56.1%, 49.9%, 49.9%, 37.3% and 25%) respectively.

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No abstract

Background: Because it tends to cause deterioration in the quality of food and appearance, food browning is unacceptable. Tyrosinase, which catalyzes the transformation of mono phenolic compounds into oquinones, has been associated with this phenomenon. Natural anti-browning agents were used to help avoid the enzymatic browning that occurs in many foods. Methods: Tyrosinase of Jerusalem Artichoke tubers was purified through (NH4)2SO4 sedimentation, dialysis, chromatography, and finally gel electrophoresis. The purified enzyme was characterized and inhibited by rosemary extracts. Results: Purification of tyrosinase from Jerusalem Artichoke tuber were accomplished. The specific activity at the final step of purification increased to 14115.76 U/mg protein with purification fold 32.89 using CM-Cellulose chromatography. The molecular mass was evaluated by electrophoresis and found to be 62 KDa. Maximum tyrosinase activity was found at 30 °C, pH 7.2, and higher affinity towards Ltyrosine. Inhibition percentage of heated extracts for leaves and flowers on tyrosinase activity was better than nonheated with 29.65% and 23.75%, respectively. The kinetic analysis exposed uncompetitive inhibition by leaves and flowers heated extracts. Conclusions: In this study, we concluded the usage of natural anti-browning inhibitors like rosemary extract be able to be castoff to substitute the chemical agents which might be dangerous to social healthiness. Natural anti-browning agents can be used to prevent the browning of many foods.