PARTIAL-PURIFICATION OF SOLUBLE POTATO POLYPHENOL OXIDASE BY PARTITIONING IN AN AQUEOUS 2-PHASE SYSTEM

Soluble potato polyphenol oxidase was partially purified using a two-phase partitioning approach with Triton X-114. The purification achieved was 5-fold from a crude extract of potato tubers, with an 18% recovery of activity. The phenols were also reduced to 3% of the original content, avoiding the postpurification tanning of the enzyme. The enzyme was kinetically characterized with two phenolic substrates (tert-butylcatechol and chlorogenic acid) at two pHs (4.5 and 6.5). The latter substrate presented inhibition at high substrate concentration with a K(Si) of 5.5 mM. Selected inhibitor agents were also studied. Tropolone was found to be the most effective inhibitor and presented a mixed type of inhibition.