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茶叶科学 ›› 2018, Vol. 38 ›› Issue (4): 396-405.doi: 10.13305/j.cnki.jts.2018.04.007

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两种原核表达载体对CsPPO蛋白表达活性的影响

甘玉迪, 孙康, 李会娟, 堵忠颖, 赵真, 庞鑫, 黎星辉, 陈暄*   

  1. 南京农业大学园艺学院,江苏 南京210095
  • 收稿日期:2018-04-04 修回日期:2018-04-26 出版日期:2018-08-15 发布日期:2019-10-15
  • 通讯作者: *chenxuan@njau.edu.cn
  • 作者简介:甘玉迪,女,硕士研究生,主要从事茶树遗传育种和茶叶生化研究。
  • 基金资助:
    国家现代农业产业技术体系建设专项资金(CARS-19)、国家自然科学基金(31470690)、江苏省现代农业产业技术体系(sxgc2017223)、南京农业大学SRT项目(1614C12)

Effect of Two Prokaryotic Expressed Vectors on the Activity of PPO from Camellia sinensis

GAN Yudi, SUN Kang, LI Huijuan, DU Zhongying, ZHAO Zhen, PANG Xing, LI Xinghui, CHEN Xuan*   

  1. College of Horticulture, Nangjing Agricultural University, Nanjing 210095, China
  • Received:2018-04-04 Revised:2018-04-26 Online:2018-08-15 Published:2019-10-15

摘要: 为了选择合适载体,获得稳定表达且具有高活性的可溶性茶树多酚氧化酶,本研究以茶树叶片为材料,克隆茶树多酚氧化酶基因(CsPPO),切除含43个氨基酸和70个氨基酸的肽段后分别与pET32a载体、pMAL-c5X载体进行重组构建原核表达载体,分别命名为pET32a-CsPPO43、pET32a-CsPPO70、pMALc5X-Cs PPO43、pMALc5X-CsPPO70,利用E. coil Transetta(DE3)菌株进行表达,经SDS-PAGE电泳检验,pMAL-c5X载体表达的目的蛋白易于提取,大量出现在上清液中;而pET32a载体表达后蛋白则基本存在于沉淀中。利用邻苯二酚、ECG、EC 3种底物在410βnm处检测CsPPO蛋白活性发现,pMALc5X-CsPPO对不同底物反应时酶活性随时间增加均呈现明显“S”型变化,表明茶树PPO氧化儿茶素类的反应并不是匀速过程。pMALc5X-CsPPO43比活力比pMALc5X-CsPPO70的高,其中pMALc5X-CsPPO43与EC反应时酶比活力最高,最大比活力为1.45×106β U·mg-1。因此,可利用pMALc5X-CsPPO43合成工业用PPO,为进一步研究其与儿茶素的反应机理,利用体外酶法高效获得茶黄素奠定基础。

关键词: 茶树, 多酚氧化酶, 原核表达, 酶活性

Abstract: To get stably soluble tea polyphenol oxidase with high activity, two vectors were selected to express CsPPO. A tea polyphenol oxidase gene was cloned from tea leaves. After trimming two peptide fragments with 43 and 70 amino acids, the sequences were connected into pET32a and pMAL-c5X vectors with BamH I/xho I and Sal I/ BamH I and named as pET32a-CsPPO43, pET32a-CsPPO70, pMALc5X-CsPPO43 and pMALc5X-CsPPO70 respectively. After expressed of recombinant plasmids in the E.coil Transetta (DE3) strain, SDS-PAGE results showed that the protein expressed by pMAL-c5X was easier extracted than that by pET32a. The proteins expressed by pMAL-c5X were found in both the supernatant and pellet, while those by pET32a were only found in the pellet. The activity of CsPPO was detected by 1,2-benzenediol, ECG and EC as substrates in 410 nm with micro-plate reader. The ‘S’ shaped curves graphed with three substrates oxidized by the pMALc5X-CsPPO indicated that all reaction speeds were not constant. The specific activity of pMALc5X-CsPPO43 was higher than that of pMALc5X-CsPPO70, with the highest activity reaching 1.45×106 βU·mg-1 when reacted to EC. Therefore, pMALc5X-CsPPO43 could be used to synthesize industrial PPO, but its role in catechin mechanism still needs further research.

Key words: Camellia sinensis, polyphenol oxidase, Prokaryotic expression, enzymatic activity

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