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	High polyphenol oxidase activity and low titratable acidity in browning bamboo tissue culture
	Huang, L. C. ; Lee, Y. L. ; Huang, B. L. ; Kuo, C. I. ; Shaw, J. F. ; Huang BL(黄本立)
	2002
关键词	Bambusa oldhamii Dendrocalamus latiflorus enzyme inhibitors Phyllostachys nigra
英文摘要	Tissue browning that frequently results in the early death of bamboo shoots in vitro correlated directly with polyphenol oxidase (PPO, EC 1.10.3.1) activity and inversely with titratable acidity. It was unrelated to the level of endogenous phenols. During the course of culture, timing of PPO activity paralleled that of explant browning. Browning was highest among shoots cultured in a medium of pH 8, which was consistent with the pH optimum of the bamboo enzyme. The pH optimum was first determined with the crude enzyme, then verified with two purified isozymes. Stability of the bamboo PPO was also highest at pH 10. PPO activities of the severely browning Dendrocalamus latiflorus, the moderately browning Phyllostachys nigra, and the relatively non-browning Bambusa oldhamii were inhibited strongly by ascorbic acid, cysteine, sodium diethyldithiocarbamate, and sodium sulfite. But characterization of bamboo PPO according to enzyme inhibitors was not possible because enzyme extracts of the three species gave varied responses to the traditional substances. Nutrient medium addenda of some PPO inhibitors, namely ascorbic acid, cysteine, kojic acid, and thiourea, mainly enhanced browning. However, ferulic acid at 3 mM and lower concentrations reduced the number of brown shoots per culture, although not the percentage of cultures that browned. Polyvinylpyrrolidone failed completely to suppress browning. The two purified isozymes showed different temperature optima for PPO activity: 60degreesC and 65degreesC. The purified isozymes displayed a substrate preference for dopamine, or a cathecol oxidase characteristic.
语种	英语
内容类型	期刊论文
源URL	[http://dspace.xmu.edu.cn/handle/2288/64479]
专题	化学化工－已发表论文
推荐引用方式 GB/T 7714	Huang, L. C.,Lee, Y. L.,Huang, B. L.,et al. High polyphenol oxidase activity and low titratable acidity in browning bamboo tissue culture[J],2002.
APA	Huang, L. C.,Lee, Y. L.,Huang, B. L.,Kuo, C. I.,Shaw, J. F.,&黄本立.(2002).High polyphenol oxidase activity and low titratable acidity in browning bamboo tissue culture..
MLA	Huang, L. C.,et al."High polyphenol oxidase activity and low titratable acidity in browning bamboo tissue culture".(2002).

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