Purification and Kinetic Characterization of an Anionic Peroxidase from Melon (Cucumis melo L.) Cultivated under Different Salinity Conditions

The partial characterization of an anionic peroxidase in melon fruit is described. Four melon peroxidase (MPX) isoenzymes were detected in crude extracts after isoelectric focusing. The major MPX isoenzyme (pI = 3.7) was partially purified by including hydrophobic and anion-exchange chromatography i...

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Veröffentlicht in:Journal of agricultural and food chemistry 2000-05, Vol.48 (5), p.1537-1541
Hauptverfasser: Rodríguez-López, Jose Neptuno, Espín, Juan Carlos, del Amor, Francisco, Tudela, José, Martínez, Vicente, Cerdá, Antonio, García-Cánovas, Francisco
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Sprache:eng
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Zusammenfassung:The partial characterization of an anionic peroxidase in melon fruit is described. Four melon peroxidase (MPX) isoenzymes were detected in crude extracts after isoelectric focusing. The major MPX isoenzyme (pI = 3.7) was partially purified by including hydrophobic and anion-exchange chromatography in the purification scheme. The sample obtained was used to characterize MPX. This peroxidase did not show activity on ascorbic acid but oxidized guaiacol at a high rate, showing an optimum pH of 5.5 when acting on this last reducing substrate. Melon fruits grown under highly saline conditions showed slightly increased levels of this anionic isoenzyme. Kinetic studies using 2,2‘-azinobis(3-ethylbenzothiazolinesulfonic acid) (ABTS) as reducing substrate showed that increased salinity in the growth medium did not modify the kinetic parameters of melon peroxidase on both hydrogen peroxide and reducing substrate. Keywords: Melon; peroxidase; salinity; peroxidase isoenzyme; enzyme kinetics.
ISSN:0021-8561
1520-5118
DOI:10.1021/jf9905774