INVESTIGADORES
ROZENFELD paula Adriana
artículos
Título:
Polyphenoloxidase activity from Selva strawberry fruit (Fragaria x ananassa, Duch.): characterisation and partial purification
Autor/es:
SERRADELL, M.A; ROZENFELD, P.A; MARTINEZ, G.A; CIVELLO, P.M; CHAVES, A.R; AÑÓN, M.C
Revista:
JOURNAL OF THE SCIENCE OF FOOD AND AGRICULTURE
Editorial:
JOHN WILEY & SONS LTD
Referencias:
Año: 2000 vol. 80 p. 1421 - 1427
ISSN:
0022-5142
Resumen:
In this work, polyphenoloxidase (PPO) from Selva strawberry fruit (Fragariaananassa,
Duch) was extracted, characterised and partially puri®ed. The activity of PPO was analysed in crude
extracts obtained from either fresh fruits or acetone powder. The presence of NaCl and Triton X-100 in
the extraction buffer caused a marked increase in enzyme extractability. The enzyme showed an
apparent Km value of 11.2mM with pyrocatechol as substrate. The maximum enzyme activity was
observed at 50°C and pH 5.3±6.0 without SDS and pH 7.2 in the presence of SDS. The presence of SDS
increased PPO activity at pH 7.2 but diminished it at pH 6.0. The enzyme showed high thermal stability
and maintained activities equal to or greater than 50% of its maximum activity in the 2.6±9.3 pH range.
One polyphenoloxidase isoenzyme was detected in crude extracts of all ripening stages, showing an
isoelectric point of 7.3. The speci®c activity of PPO decreased continuously through fruit ripening.
Maximum speci®c activities were found at the `small green´ and `large green´ ripening stages. A total
enzyme extract was partially puri®ed by means of (NH4)2SO4 precipitation and cationic exchange
chromatography in an FPLC system. The puri®cation grade achieved was near 25. The partially
puri®ed enzyme showed an isoelectric point equal to 7.3 and a molecular mass of 1354kDa for the
native protein.Fragariaananassa,
Duch) was extracted, characterised and partially puri®ed. The activity of PPO was analysed in crude
extracts obtained from either fresh fruits or acetone powder. The presence of NaCl and Triton X-100 in
the extraction buffer caused a marked increase in enzyme extractability. The enzyme showed an
apparent Km value of 11.2mM with pyrocatechol as substrate. The maximum enzyme activity was
observed at 50°C and pH 5.3±6.0 without SDS and pH 7.2 in the presence of SDS. The presence of SDS
increased PPO activity at pH 7.2 but diminished it at pH 6.0. The enzyme showed high thermal stability
and maintained activities equal to or greater than 50% of its maximum activity in the 2.6±9.3 pH range.
One polyphenoloxidase isoenzyme was detected in crude extracts of all ripening stages, showing an
isoelectric point of 7.3. The speci®c activity of PPO decreased continuously through fruit ripening.
Maximum speci®c activities were found at the `small green´ and `large green´ ripening stages. A total
enzyme extract was partially puri®ed by means of (NH4)2SO4 precipitation and cationic exchange
chromatography in an FPLC system. The puri®cation grade achieved was near 25. The partially
puri®ed enzyme showed an isoelectric point equal to 7.3 and a molecular mass of 1354kDa for the
native protein.Km value of 11.2mM with pyrocatechol as substrate. The maximum enzyme activity was
observed at 50°C and pH 5.3±6.0 without SDS and pH 7.2 in the presence of SDS. The presence of SDS
increased PPO activity at pH 7.2 but diminished it at pH 6.0. The enzyme showed high thermal stability
and maintained activities equal to or greater than 50% of its maximum activity in the 2.6±9.3 pH range.
One polyphenoloxidase isoenzyme was detected in crude extracts of all ripening stages, showing an
isoelectric point of 7.3. The speci®c activity of PPO decreased continuously through fruit ripening.
Maximum speci®c activities were found at the `small green´ and `large green´ ripening stages. A total
enzyme extract was partially puri®ed by means of (NH4)2SO4 precipitation and cationic exchange
chromatography in an FPLC system. The puri®cation grade achieved was near 25. The partially
puri®ed enzyme showed an isoelectric point equal to 7.3 and a molecular mass of 1354kDa for the
native protein.°C and pH 5.3±6.0 without SDS and pH 7.2 in the presence of SDS. The presence of SDS
increased PPO activity at pH 7.2 but diminished it at pH 6.0. The enzyme showed high thermal stability
and maintained activities equal to or greater than 50% of its maximum activity in the 2.6±9.3 pH range.
One polyphenoloxidase isoenzyme was detected in crude extracts of all ripening stages, showing an
isoelectric point of 7.3. The speci®c activity of PPO decreased continuously through fruit ripening.
Maximum speci®c activities were found at the `small green´ and `large green´ ripening stages. A total
enzyme extract was partially puri®ed by means of (NH4)2SO4 precipitation and cationic exchange
chromatography in an FPLC system. The puri®cation grade achieved was near 25. The partially
puri®ed enzyme showed an isoelectric point equal to 7.3 and a molecular mass of 1354kDa for the
native protein.4)2SO4 precipitation and cationic exchange
chromatography in an FPLC system. The puri®cation grade achieved was near 25. The partially
puri®ed enzyme showed an isoelectric point equal to 7.3 and a molecular mass of 1354kDa for the
native protein.4kDa for the
native protein.