Εξειδίκευση τύπου :	Άρθρο σε επιστημονικό περιοδικό
Τίτλος:	Oxidation of oleuropein studied by EPR and spectrophotometry
Δημιουργός/Συγγραφέας:	Tzika, Evaggelia D. [EL] Παπαδημητρίου, Βασιλική[EN] Papadimitriou, Vassiliki [EL] Σωτηρούδης, Θεόδωρος Γ.[EN] Sotiroudis, Theodore G. [EL] Ξενάκης, Αριστοτέλης[EN] Xenakis, Aristotelis
Ημερομηνία:	2008
Γλώσσα:	Αγγλικά
Περίληψη:	The autoxidation at alkaline pH and enzymatic oxidation by mushroom tyrosinase of oleuropein, the dominant biophenol present in the fruits and leaves of Olea europea, was followed by both electron paramagnetic resonance (EPR) and absorption spectroscopy. For comparison, the same oxidation processes were applied to 4-methylcatechol, a simple polyphenol present in olive mill wastewaters. EPR spectra of stable o-semiquinone radicals produced during autoxidation at pH 12 and short-lived o-semiquinone free radicals produced during autoxidation at pH 9.0 or tyrosinase action and stabilized by chelation with a diamagnetic metal ion (Mg2+) were recorded for both polyphenols, and the corresponding hyperfine splitting constants were determined. The UV-Vis spectral characteristics of the oxidation of polyphenols were highly dependent on the type of polyphenol, oxidant type and the pH of the reaction. The kinetic behavior of tyrosinase in the presence of oleuropein and 4-methylcatechol was followed by recording spectral changes at 400 nm (absorption maximum) over time. The tysosinase activity with oleuropein showed a pronounced pH optimum at pH 6.5 and a minor one around pH 8. From the data analysis of the initial rate at pH 6.5, the kinetic parameters Km = 0.34 ± 0.03 mM and Vmax = 0.029 ± 0.002 A400 min-1 were determined for oleuropein.
Τίτλος πηγής δημοσίευσης:	European Journal of Lipid Science and Technology
Τόμος/Κεφάλαιο:	110
Τεύχος:	2
Σελίδες:	149-157
Θεματική Κατηγορία:	[EL] Βιολογία (Γενικά)[EN] Biology (General)
Λέξεις-Κλειδιά:	Oleuropein 4-Methylcatechol Tyrosinase Electron paramagnetic resonance (EPR) spectroscopy
Κάτοχος πνευματικών δικαιωμάτων:	© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim
Σημειώσεις:	This article has been published in the journal, European Journal of Lipid Science and Technology [© Wiley-VCH Verlag]. The definitive version: Evaggelia D. Tzika, Vassiliki Papadimitriou, Theodore G. Sotiroudis, Aristotelis Xenakis, 2008. Oxidation of oleuropein studied by EPR and spectrophotometry. European Journal of Lipid Science and Technology, Volume 110, Issue 2, Pages 149 – 157, is available at: http://dx.doi.org/10.1002/ejlt.200700163 Journal Web Location:http://www3.interscience.wiley.com/journal/69502350/home
ΙΒΦΧΒ: αρχειακή συλλογή:	Ινστιτούτο Βιολογικών Ερευνών και Βιοτεχνολογίας (ΙΒΕΒ) (έως 2012)
Εμφανίζεται στις συλλογές:	Ινστιτούτο Χημικής Βιολογίας - Επιστημονικό έργο