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Three polyphenol oxidase(polyphenol oxidase I , II and III ) were isolated from the crude extract of a Spuriopimginella bracycarpa by(NH₄)₂SO₄precipitation and subsequent Sephadex G-150 chromatography. The final preparation thus obtained showed three peaks of enzyme activity. Optimum pH and temperature for the activity of polyphenol oxidase were 7.5 and 30℃, respectively. The enzyme was completely inactivated when it, was treated a1. 70℃ for 30min and at 80℃ for 5min at pH 6.5. The enzyme was partially inactivated by ascorbic acid, glutathione and potassium cyanide (O.1mM), and was completely inhibited by L-cysteine, ascorbic acid, glutathione and po-tassium cyanide(0.5 and 1.0mM). The enzyme has good activity on catechol and 3,4-dihydroxytoluene but was strongly inactivated on pyrogallol, dopamine and DL-dopa. The Michaelis constant. of the enzyme was 86.5mM with catechol as a substrate(Received February 1, 1991, Accepted March 25, 1991).
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