| Abstract: | Polyphenoloxidase (EC 1.10.3.1) in eggplant (Solatium melongena L) was purified by ammonium sulphate fractionation, DEAE-Cellulofine and DEAE-Toyopearl chromatography and Sephadex G-100 gel filtration. The enzyme was purified about 110-fold with a recovery of 5%. The purified enzyme more quickly oxidised chlorogenic acid (5-caffeoylquinic acid, IUPAC) than 10 other substrates used. The Km value for the enzyme was found to be 0·50 mM with respect to chlorogenic acid; the optimum pH of the enzyme was about 4 with enzyme stability between pH 5 and 8. The enzyme was completely inactivated after heat treatment at 75°C for 30 min or 80°C for 5 min. Sodium metabisulphite, potassium cyanide and sodium fluoride markedly inhibited the enzyme activity. |
