Characterization of polyphenol oxidase from broccoli (Brassica oleracea var. botrytis italica) florets |
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Authors: | Urszula Gawlik-Dziki Urszula Szymanowska Barbara Baraniak |
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Affiliation: | Department of Biochemistry and Food Chemistry, Agricultural University, ul. Skromna 8, 20-704 Lublin, Poland |
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Abstract: | Polyphenol oxidase (PPO) from broccoli florets was extracted and purified through (NH4)2SO4 precipitation, ion-exchange and gel filtration chromatography. The molecular weight was estimated to lie between 51.3 and 57 kDa by sodium dodecyl sulphate-polyacrylamide gel electophoresis (SDS-PAGE) and gel filtration. The effects of substrate specificity, pH, and sensitivity to various inhibitors: citric acid, ascorbic acid, sodium sulphate and EDTA (sodium salt of ethylenediaminetetraacetic acid) of partially purified PPO were investigated. Polyphenol oxidase showed the best activity toward catechol (KM = 12.34 ± 0.057 mM, Vmax = 2000 ± 8736 U/ml/min) and 4-methyl catechol (KM = 21 ± 0.087 mM, Vmax = 28.20 ± 0.525 U/ml/min). The optimum pH for broccoli PPO was 5.7 with catechol and 4-methylcatechol as substrates. The most effective inhibitor was sodium sulphate. |
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Keywords: | Polyphenol oxidase Broccoli Inhibitors |
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