Characteristics of polyphenol oxidase from Sargassum fusiforme

Crude polyphenol oxidase (PPO) was obtained from Sargassum fusi forme by lixiviation. and saltingout with (NH_(3))_(2)SO_(4), and the enzyme properties were examined. The results were as follows; the PPO activity increased linearly with the increase of catechol substrate volume if the volume of catechol substrate was 0.3 - 1.2 mL, and decreased when the volume of the substrate was greater than 1.2 mL in the reaction system; the enzymatic activity was the highest when the ratio of the catechol substrate content to PPO content was 2 : l; the suitable temperature for the PPO activity was 35 - 60 ℃ and the optimum temperature was 40-45 ℃. the enzymatic activity declined sharply when the temperature exceeded 60 ℃; in the con-dition of 50 - 100 ℃ hot water treating for 1 h, the activity of enzyme lost 50% - 75% s the PPO could act at alkaline conditions , the best enzymatic activity was detected in the condition of pH 9.1, and the activity remained high even in the condition of pH 11 and pH 12. The result showed that the PPO extracted from 5. fusi forme was different from that extracted from ter-ricolous plants, for example, the latter had normal enzymatic activity in acidic conditions. Isoenzymes in the crude PPO extracted from 5. fusi forme were also found in this study. All the five materials tested showed some degree of inhibition to PPO activity, but the most effective inhibitors were NaHSO_(3) and L-cysteine, which inactivated the PPO completely at the concen-tration of 50 #mu#mol·L~(-1).