Abstract
A polyphenol oxidase [EC class 1.10.3] was purified from culture filtrates of Chaetomium thermophile Isolate o-453 by procedures including salting- out by ammonium sulfate and combined column chromatography on DEAE-Toyopearl 650S, Con A-Sepharose, hydroxylapatite, and Sephadex G-200. The final enzyme preparation was homogeneous on polyacrylamide gel disc electrophoresis. Its estimated molecular weight was approximately 98, 000 by gel filtration. It showed maximum activity at pH 5.0 and at 55°C. The purified enzyme was very stable between pH 4.0 and 11.0 and up to 55°C. It was highly active toward d-catechin (100%), p- hydroquinone (45.7%), and N, N-dimethyl-p-phenylenediamine (63.0%). Though pyrocatechol (22.6%) was oxidized to some extent, DL-DOPA (0.33%) and o-phenylenediamine (3.1%) were hardly oxidized by the enzyme.
