| Abstract: | Separation of polyphenoloxidase isoenzymes based on their charge properties was achieved by isoelectric focusing on Sephadex G-75 thin layers containing a mixture of ampholytes in the pH ranges 4–6 and 3–10. The separated isoenzymes can be detected as colored zones by a print technique in which a dried filter paper, previously buffered with 0.1 m phosphate buffer, pH 7,0, and impregnated with 1% substrate in methanol, is placed onto the gel layer. d-Catechin and tyramine were the best substrates for detecting the diphenolase and monophenolase activities, respectively. Using this technique, two commercial preparations of mushroom tyrosinase were found to consist of 7 and 15 isoenzymes, while enzyme preparations from two potato varleties showed 11 to 15 isoenzymes. The isoenzymes of potato and mushroom polyphenoloxidase showed marked differences in their pI values. |
