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Research Article
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Purification, Characterization and Effect of Physico-chemical Agents on Stability of Polyphenoloxidase from Sajna (Moringa oleifere L.) Leaves at Mature Stage
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Shahanaz Khatun,
Nurul Absar
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M. Ashraduzzaman
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ABSTRACT
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Polyphenoloxidase (PPO), a highly active oxidative enzyme in Sajna leaves at mature stage was purified by ion exchange chromatography on DEAE-cellulose followed by CM-cellulose. The purified enzyme was monomer in nature and its molecular weight was estimated to be 56,000 and 55,500 by gelfiltration and SDS-PAGE respectively. The enzyme appeared to be a single polypeptide chain as revealed by SDS-PAGE either in presence or absence of reducing agent. The enzyme has following characteristics : optimum pH 6.2, optimum temperature 32°C, Km value 0.047M against catechol as substrate and maximum absorption 279 nm. The activity of the enzyme was enhanced by Ca2+ and Cu2+ but its activity lost completely in presence of ascorbic acid, EDTA, KCN and NaHSO3.
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