Firstly, polyphenol oxidase (PPO) was purified from the fruits of Opuntia ficus-indica using Sepharose 4B–L-tyrosine–p-aminobenzoic acid affinity chromatography, and the enzyme was characterized. The PPO was purified 20.59-fold. Thereafter, PPO was performed on sodium dodecyl sulfate–polyacrylamide gel electrophoresis (SDS-PAGE). The kinetic parameters, optimum pHs, and optimum temperatures were investigated for three substrates. Opuntia ficus-indica PPO’s optimum pH and optimum temperature were 9.0 and 20 °C; 7.5 and 20 °C; and 7.5 and 30 °C, respectively, when using pyrogallol, catechol, and 4-methyl catechol as substrates. For the pyrogallol, catechol, and 4-methyl catechol, the Km, Vmax, and Vmax/Km values were determined as 16.67 mM, 833.33 U/mLmin, and 50 U/mLminmM; 6.33 mM, 126.58 U/mLmin, and 20 U/mLminmM; and 5.38 mM, 107.53 U/mLmin, and 20 U/mLminmM, respectively. As a result, pyrogallol was a more appropriate substrate than catechol and 4-methyl catechol for the PPO from Opuntia ficus-indica.

Polyphenol oxidase (PPO) was purified and characterized from a dried wild edible and medicinal mushroom (V. bombycina). Using Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography, PPO was purified from the dried V. bombycina. The purification was completed with a 33.85-fold purification. On sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE), the purified enzyme migrated as a single band. The molecular weight of the purified enzyme was estimated by SDS-PAGE to be about 25 kDa. Catechol, 4-methyl catechol, and pyrogallol were used as substrates to determine the enzyme activity and its kinetic parameters (Km and Vmax). At the optimum pH and temperature, dried V. bombycina PPO’s Km and Vmax values for catechol, 4-methyl catechol, and pyrogallol were found to be 1.67 mM–833.33 U/mL, 3.17 mM–158.73 U/mL, and 2.67 mM–3333.33 U/mL, respectively. Also investigated were the effects of pH and temperature on the enzymatic properties of PPO in dried V. bombycina. The optimum pH and temperature values for dried V. bombycina PPO obtained by using catechol, 4-methyl catechol, and pyrogallol as substrates were 6.5, 15 °C; 9.0, 20 °C; and 8.0, 15°C, respectively. This is the first study on the purification and characterization of PPO from dried V. bombycina.

Comparison of Serum Paraoxonase 1 (PON1) Activities Among Different Sheep Breeds in Turkey

PPO was purified from immature and mature Japanese pears (Pyrus pyrifolia) fruits through the Sepharose-4B-L-tyrosine-p-aminobenzoic acid affinity column. PPOs were purified 5.21 fold and 9.77 fold from immature and mature Japanese pears, respectively. SDS-PAGE of PPOs from there was performed. Using catechol, 4-methyl catechol, and pyrogallol as substrates, the K_m and V_max values for immature Japanese pear PPO were calculated to be 7.14 mM, 1428.57 U/(mL min); 3.33 mM, 3333.33 U/(mL min); and 6.00 mM, 10 000.00 U/(mL min), respectively. Using catechol, 4-methyl catechol, and pyrogallol as substrates, the K_m and V_max values for mature Japanese pear PPO were calculated to be 1.31 mM, 163.93 U/(mL min); 3.57 mM, 357.14 U/(mL min); 2.50 mM, 5000.00 U/(mL min), respectively. Using catechol, 4-methyl catechol, and pyrogallol as substrates, the optimum pH and temperature values for immature Japanese pear PPO were determined to be 6.5, 15°C; 6.0, 40°C; and 8.0, 15°C, respectively. Using catechol, 4-methyl catechol, and pyrogallol as substrates, the optimum pH and temperature values for mature Japanese pear PPO were determined to be 9.0, 40°C; 7.0, 15°C; and 7.5, 30°C, respectively.

A comparative study of the properties of healthy and apple scar skin viroid (ASSVd) infected apple fruit polyphenol oxidase (PPO) from apple cultivar Starking Delicious was carried out for the first time. PPOs from apple fruits were purified with a Sepharose 4B-L-tyrosine-p-aminobenzoic acid affinity chromatography. The activity of PPO in healthy and ASSVd infected apples was evaluated using the spectrophotometric method. PPO activity was determined using catechol as a substrate. Higher PPO activity was observed in ASSVd infected fruits as compared to healthy ones. Both healthy and ASSVd infected apples PPO produced two bands of approximately 66 and 40 kDa on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The pure enzymes were used to characterize enzyme at different pHs (from 4.5 to 9) and temperatures (from 15 to 45°C). For PPO from ASSVd-infected and healthy apples, the optimum pHs were 7.5 and 8.0, and the optimum temperatures were 15°C and 20°C, respectively. The Michaelis–Menten constant (K_m) and the maximum reaction rate (V_max) for healthy apple PPO were 10 mM and 3333.33 U/(mL min), whereas those for ASSVd infected apple PPO were 30 mM and 5000.00 U/(mL min), respectively.