1. Preparative Isoelectric focusing (PIEF) was used to isolate hydroxylasic and dehydrogenasic activities, at different pI. 2. The fraction at pI 4.7 and 4.9 displays a pure dehydrogenase activity (substrate L-DOPA). 3. This fraction did not react with tyrosine, either in the spot-test or in absorption spectra (200-620 nm), and did not exhibit any oxygen consumption. 4. The fraction at pI 4.1 and 4.3 reacted with both L-DOPA and tyrosine as substrate, showing dehydrogenase and hydroxylase activity. 5. The latter activity was confirmed by the oxygen consumption test, showing that molecular oxygen is used to ortho-hydroxylate tyrosine.
THE AGARICUS BISPORUS TYROSINASE 2: CHARACTERIZATION OF HYDROXYLASE AND DEHYDROGENASE ACTIVITIES.
PESSIONE, Enrica;GIUNTA, Carlo
1994-01-01
Abstract
1. Preparative Isoelectric focusing (PIEF) was used to isolate hydroxylasic and dehydrogenasic activities, at different pI. 2. The fraction at pI 4.7 and 4.9 displays a pure dehydrogenase activity (substrate L-DOPA). 3. This fraction did not react with tyrosine, either in the spot-test or in absorption spectra (200-620 nm), and did not exhibit any oxygen consumption. 4. The fraction at pI 4.1 and 4.3 reacted with both L-DOPA and tyrosine as substrate, showing dehydrogenase and hydroxylase activity. 5. The latter activity was confirmed by the oxygen consumption test, showing that molecular oxygen is used to ortho-hydroxylate tyrosine.
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