共查询到19条相似文献，搜索用时 312 毫秒
1.
莲多酚氧化酶基因的克隆及序列分析 总被引：4，自引：2，他引：2
多酚氧化酶是一类普遍存在于植物、真菌、昆虫的质体中,由核基因编码能与铜相结合的金属蛋白酶。它是许多果蔬等农产品酶促褐变的主因,也在植物的光合作用、抗病虫害、生长发育以及花色的形成中起一定作用。用RT—PCR方法,从中国莲（Nelumbo nucifera）幼叶RNA中成功扩增出ppo的部分序列,经克隆测序,得到长度在978-1057bp的序列共7个,编码326～352个氨基酸。与其他物种PPO进行比较,其核苷酸序列相似性为83％-85％,氨基酸序列相似性为84％99％。莲ppo的成功克隆为抑制莲藕的酶促褐变,提高莲的抗虫抗病性等的研究打下了良好的基础。 相似文献
2.
为获得无核白葡萄中多酚氧化酶(PPO)的基因序列,以无核白葡萄果实为试材,进行基因同源克隆,得到多酚氧化酶基因CDS全长序列,其完整的编码框为1 824 bp,编码607个氨基酸(GenBank登陆号为KP271928);系统进化分析可知,其与葡萄科植物PPO基因同源性最高;生物信息学方法发现该蛋白分子量为67 392.44 Da,等电点为6.42,具典型的酪氨酸家族结构域,无信号肽结构,但有一个跨膜结构域,为亲水性蛋白;二级结构预测发现,PPO具有CuA与CuB两个结合区,分别嵌入蛋白活性腔中。该研究为进一步从分子水平探讨多酚氧化酶与褐变的关系奠定理论基础。 相似文献
3.
以4种不同来源的梨基因组DNA为模板,根据已经发表的多酚氧化酶基因序列设计引物,利用PCR技术,克隆到了鸭梨、雪花梨、砂梨、黄冠梨约1．8kb的完整多酚氧化酶基因,将纯化后的扩增产物克隆到质粒pGEM-T veetor中,转化DH-5α菌,挑选阳性克隆进行测序。利用Clustalx软件对PPO核苷酸序列进行了同源性分析,用DNAStar软件对PPO核苷酸序列进行进化树分析,并进行部分植物PPO氨基酸的同源性分析。结果表明,4种梨多酚氧化酶基因的蛋白编码区含有1782个核苷酸,鸭梨基因已经在GenBank上登录,登录号为EU048225。梨多酚氧化酶基因与其他植物中的多酚氧化酶基因有较高的相似性,尤其在铜离子结合部位,所有的植物基本上一致;5种梨的同源性高达98％。基于植物PPO基因核苷酸序列的分子进化树显示,可分为两大类,梨的多酚氧化酶可以与大多数的木本植物聚合成一个组。 相似文献
4.
《分子植物育种》2020,(14)
多酚氧化酶(PPO)是果蔬发生酶促褐变的关键酶。在有氧条件下,PPO能够催化酚类化合物产生醌,而醌能够进一步通过与细胞内大分子聚合反应产生色素物质沉积在损伤组织表面,从而发生酶促褐变。酶促褐变导致植物组织表面发生褐变,并伴随着果蔬产品营养及感官品质的下降,是果蔬等农产品加工面临的主要问题之一。深入了解多酚氧化酶基因对今后抗酶促褐变品种的培育以及分子改良具有重要意义。因此,本综述从PPO基因与酶促褐变的关系、基因表达模式、蛋白结构、生理功能、以及在茄科类植物上的研究进展几个方面综述了近年来对植物中多酚氧化酶基因的研究成果,以期为作物抗酶褐变分子育种提供参考。 相似文献
5.
为了从分子水平深入了解鸭梨多酚氧化酶结构特点,基于已知的鸭梨多酚氧化酶基因cDNA片段序列设计引物,以鸭梨果实总mRNA为模板,对该基因cDNA 5’端和3’端未知序列进行了RACE扩增,最终获得鸭梨多酚氧化酶基因cDNA全长序列。该序列长度为2126 bp,开放性读码框位于136~1917 bp之间,可编码593个氨基酸残基。对该基因所翻译的氨基酸序列进行生物信息学分析,结果表明基因编码的多酚氧化酶属酪氨酸酶超级家族成员,三级空间结构为可溶性球状蛋白,不具备跨膜结构,在细胞中的定位应该位于类囊体腔中。这些生物信息的获得将为今后应用生物技术开展鸭梨多酚氧化酶的调控从而抑制鸭梨果实褐变提供十分重要的参考资料。 相似文献
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天津地区主产虾类多酚氧化酶抑制剂的筛选及应用 总被引：1，自引：0，他引：1
多酚氧化酶（PPO）是普遍存在于动植物体内的一种生物酶,它造成食品的褐变,从而严重影响食品的品质。本文以天津地区主产虾类为研究对象,研究了虾的褐变的感官评价与测定多酚氧化酶的活性相结合的方法,分别探讨了抗坏血酸、柠檬酸、植酸等抑制剂对多酚氧化酶的抑制效果,并测得生产贮运过程中使用该抑制剂的浓度与用量。结果表明,在虾中加入0．2％的抗坏血酸时,对PPO抑制效果较好,添加柠檬酸和植酸时效果不明显。 相似文献
8.
库尔勒香梨采后果实褐变机理及控制途径 总被引：1，自引：0，他引：1
库尔勒香梨采后果实褐变,不仅与酚类物质和多酚氧化酶（PPO）含量、分布有关,而且还与细胞膜结构变化密切相关。本文对库尔勒香梨果实褐变机理、控制途径及技术问题进行综述。 相似文献
9.
《分子植物育种》2016,(11)
叶黄素循环在逆境胁迫中对植物光系统起着重要的保护作用。紫黄质脱环氧化酶(VDE)和玉米黄质环氧化酶(ZEP)是调控叶黄素循环的关键酶。本研究采用RT-PCR和RACE技术率先从草莓中克隆获得VDE和ZEP基因。VDE基因c DNA全长1 842 bp,ORF为1 467 bp,编码489个氨基酸;ZEP基因c DNA全长2 325 bp,ORF为1 980 bp,编码660个氨基酸。生物信息学分析表明草莓VDE与ZEP基因所编码的氨基酸序列与蔷薇科的苹果、桃和梅等植物的亲缘关系较近。荧光定量分析发现VDE和ZEP基因在草莓根、茎、叶、花、果实中皆有表达,说明二者均为组成型表达基因,并且叶片中基因的表达量最高而根中最低,推测与其在草莓叶黄素循环调控的作用有关。 相似文献
10.
橄榄总多酚含量及多酚氧化酶活性与组培褐变关系的研究 总被引：1，自引：1，他引：0
摘要：本文采集了不同月份下橄榄的不同组织部位,包括老叶、成熟叶、嫩叶、叶柄、幼嫩茎段和去皮的幼嫩茎段、橄榄果实的胚等9个不同部位;研究了这些样品中总多酚含量、多酚氧化酶（PPO）活性和组织培养褐变的关系。研究发现三月份橄榄各部位的总酚含量、PPO活性和褐变率都较低;特别是去皮的幼嫩茎段具有最低的总酚含量和PPO活性, 在组培过程中褐变程度也最低,更易诱导出愈伤组织,是橄榄组织培养过程中选择的理想外植体。实验结果表明,橄榄外植体的褐变是受到酚类物质的含量和PPO的活性影响的,多酚含量与PPO活性越高,越容易引起外植体褐变。 相似文献
11.
Browning is the main physiological disorder of ‘Yali’ pear (Pyrus bretschneideri Rehd) during storage. In this study, the relationships between browning development in fruit from different harvest dates, and cooled either rapidly or slowly, with polyphenol oxidase (PPO) activity and isozymes, and PPO gene expression has been investigated. Development of browning was highest in late-harvest fruit in both core and flesh tissues and was higher in rapidly cooled than slowly cooled fruit. Mid-harvest fruit had the lowest browning incidence and PPO activity of core tissue was higher than in flesh and seeds, while the peak of PPO activity in mid-harvest fruit was the lowest. Six PPO isoenzymes were detected in fruit, three bands A, B and E in flesh and core tissues, three bands C, D and F in the seeds. The intensity of PPO isoenzyme staining of bands A and B in pulp and core was similar to that of PPO activity and browning incidence. PPO gene expression increased and then decreased in core tissues. Trends of expression were similar to those of PPO activity. Rapid cooling promoted the expression PPO. The results suggest PPO plays an important role in ‘Yali’ pear browning during storage. 相似文献
12.
The effects of salicylic acid (SA) treatment on chilling injury, disease incidence, electrolyte leakage, malondialdehyde (MDA) content, respiration rate and ethylene production, polyphenol oxidase (PPO) and peroxidase (POD) activities, and polyamine (PA) content of ‘Qingnai’ plum fruit were examined. Chilling injury, disease incidence, electrolyte leakage, MDA content, respiration and ethylene production of control fruit increased after about 15-30 days cold storage. Chilling injury promoted PPO and POD activities which were associated with fruit flesh browning. Accompanied by a polyamine content increase, chilling injury was positively correlated with putrescine and spermine contents in control fruit. Suppression of chilling injury by SA was associated with reducing leakage, MDA content, delayed activities of PPO and POD, and enhanced PA accumulation. SA treatment delayed the onset of the climacteric peak of respiration, and also inhibited respiration and ethylene production. The results suggest that SA treatment may be used commercially to control chilling injury in ‘Qingnai’ plum fruit during cold storage. 相似文献
13.
不同梨果实褐变特异性分析 总被引：8，自引：1，他引：7
以黄金梨、大香水、新梨七号为试材,研究了贮藏后梨褐变不同部位酚类物质含量和种类、多酚氧化酶(PPO)、超氧化物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)的活性及可溶性蛋白的关系。结果表明,梨果实中的酚类物质以绿原酸为主,果实褐变与酚类物质含量和多酚氧化酶活性,特别是二者在果实中不同部位的分布特性有关。黄金梨果心与其他部位比较具有较高的酚类物质含量和PPO活性。由果皮至果心CAT活性依次降低,而果皮中POD活性极大地高于其他部位。SOD的活性与褐变的直接关系不明显。 相似文献
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多酚氧化酶（PPO）是酶促褐变的关键酶,与果蔬加工制品的色泽、抗氧化能力密切相关。以蜜梨果实为原料,邻苯二酚为底物,采用分光光度法研究蜜梨多酚氧化酶的酶学特性。结果表明：pH和温度对蜜梨PPO活性有明显的影响,其最适pH为4．5,最适温度为34℃。在加工过程中,可通过调节pH和温度来降低蜜梨PPO活性,减少褐变的发生：蜜梨PPO催化底物邻苯二酚的酶促反应动力学与米氏方程高度符合,R^2-0．9972,其动力学方程为专1/V=0．17371/[S]＋0．4775,最大反应速率Vmax=2．09U·min^-1,米氏常数Km=0．36mol·L^-1;蜜梨PPO具有一定的热稳定性,随着温度的提高。完全抑制PPO活性所需要的时间逐渐减少。采用短时高温（90℃,1min）的热处理,不仅可有效降低蜜梨加工过程中的酶促褐变．而且可减少蜜梨汁营养成分的损失．较好地保持其固有色泽。 相似文献
16.
以酥梨为试材,研究了(0±0.5)℃条件下不同O2浓度梯度和CO2浓度梯度的气调贮藏对酥梨采后生理及果实褐变的影响。结果表明:在贮藏期内,当CO2浓度为0%时,随着O2浓度的降低,在一定程度上可以延缓酥梨果肉组织相对电导率的升高、酚类物质的下降、多酚氧化酶活性的上升及色泽的转黄;但当O2浓度为1.5%时,会对酥梨果实造成伤害,引起多酚氧化酶活性上升,果心褐变指数升高;当O2浓度为5%时,CO2浓度的升高有效保持了果实的硬度、色泽;但当CO2浓度为8%时,会导致酥梨果实相对电导率增幅加大,果心、果肉酚类物质氧化加剧,果心褐变指数升高。综上所述,酥梨适宜的气调指标阈值为CO2<2%,O2为3%~5%。 相似文献
17.
P. Yingsanga V. Srilaong S. Kanlayanarat S. Noichinda W.B. McGlasson 《Postharvest Biology and Technology》2008,50(2-3):164-168
Rambutan (Nephelium lappaceum Linn.) fruit cvs. Rongrien and See-Chompoo were stored in low (60–70%) and high (85–95%) relative humidity (RH) environments at 25 °C for 6 d. Changes in weight loss, browning index, phenols content and activities of phenylalanine ammonia-lyase (PAL), polyphenol oxidase (PPO) and peroxidase (POD) were measured. By d 6 of storage, browning was severe in the spinterns but slight in the peel of both cultivars. High RH delayed spintern browning but had only a small effect on peel browning. The phenols content and PAL activity in peel from both cultivars were generally higher than in the spinterns. RH had no effect on the changes in phenols during storage but PAL activity increased in the peel but not spinterns of both cultivars at d 4 of storage in low RH. The initial activities of PPO and POD in spinterns of both cultivars were higher than in peel. PPO activity in the spinterns of both cultivars was similar and was not affected by RH. The initial activity of POD was lower in the peel and the spinterns of Rongrien fruit but there were no clear responses to RH during storage. Higher activities of PPO and POD in the spinterns compared to the peel may also be a factor in the higher rates of browning of the spinterns. 相似文献
18.
Partial purification and some properties of polyphenol oxidase extracted from litchi fruit pericarp 总被引：4，自引：0，他引：4
Litchi (Litchi chinensis Sonn.) fruit peel polyphenol oxidase (PPO) was partially purified 21 fold by ammonium sulfate fractionation and gel filtration. Pyrogallol, catechol, and 4-methylcatechol were good substrates for the enzyme; with no activity observed with chlorogenic acid, p-cresol, resorcinol, or tyrosine. The optimal pH for PPO activity was 7.0 with 4-methylcatechol, with the enzyme being most stable at pH 7.4. The enzyme was relatively temperature stable with maximum activity at 70 °C and requiring a little less than 10 min at 90 °C for 50% loss of activity. The Km and Vmax for the enzyme, with 4-methylcatechol, were 10 mM and 1.47 × 104 units/min per mg protein, respectively. The enzyme was not activated by SDS. Reduced glutathione,
-cysteine, tropolone, thiourea, FeSO4, and SnCl2 markedly inhibited PPO activity, whereas MnSO4 and CaCl2 enhanced PPO activity. Data obtained in this study might help to better understand and control commercially, litchi fruit peel browning. 相似文献