共查询到20条相似文献，搜索用时 46 毫秒
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L Pouvreau H Gruppen S R Piersma L A van den Broek G A van Koningsveld A G Voragen 《Journal of agricultural and food chemistry》2001,49(6):2864-2874
Protease inhibitors from potato juice of cv. Elkana were purified and quantified. The protease inhibitors represent ca. 50% of the total soluble proteins in potato juice. The protease inhibitors were classified into seven different families: potato inhibitor I (PI-1), potato inhibitor II (PI-2), potato cysteine protease inhibitor (PCPI), potato aspartate protease inhibitor (PAPI), potato Kunitz-type protease inhibitor (PKPI), potato carboxypeptidase inhibitor (PCI), and "other serine protease inhibitors". The most abundant families were the PI-2 and PCPI families, representing 22 and 12% of all proteins in potato juice, respectively. Potato protease inhibitors show a broad spectrum of enzyme inhibition. All the families (except PCI) inhibited trypsin and/or chymotrypsin. PI-2 isoforms exhibit 82 and 50% of the total trypsin and chymotrypsin inhibiting activity, respectively. A strong variation within the latter activities was shown within one family and between protease inhibitor families. 相似文献
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不同化感潜力水稻化感效应与产量的关系 总被引：2，自引：0，他引：2
本研究探讨了连续3年5种不同化感潜力水稻田间抑草效应、产量及其之间相互关系。结果表明,不同种植时间,不同化感潜力水稻田间种植过程中伴生杂草总生物量以非化感水稻"Lemont"最大,化感水稻"PI-1"最小。化感潜力分析结果表明,不同化感潜力水稻以化感水稻"PI-1"化感抑草潜力最强,非化感水稻"Lemont"最弱。水稻产量分析结果表明,不除草条件下,不同种植时间均以化感水稻"PI-1"产量最高,非化感水稻"Lemont"产量最低。除草条件下,依然以化感水稻"PI-1"产量最高,化感水稻"IAC47"产量最小。杂草生物量、水稻化感潜力与水稻产量的相关性分析结果表明,不同化感潜力水稻产量的大小与田间杂草生物量存在极显著负相关,与化感潜力大小存在极显著正相关。 相似文献
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黑曲霉木聚糖酶基因xynB在大肠杆菌中的表达及重组木聚糖酶的特性 总被引：1，自引：0，他引：1
从黑曲霉(Aspergillus niger) mafic-005中克隆得到木聚糖酶基因xynB。序列分析表明，该基因全长745 bp，含有一个67 bp内含子，编码225个氨基酸，理论分子量为24 kD(GenBank登录号:DQ174549)，与已知黑曲霉xynB基因的同源性均较高。将该基因定向插入大肠杆菌(Escherichia coli )表达载体pET-28a (+)上，并转化E. coli BL21 获得重组菌株。经过IPTG诱导，xynB基因获得特异性表达。经SDS-PAGE分析，重组蛋白分子量约为30 kD。该重组蛋白经镍NTA琼脂糖凝胶FF纯化后达到电泳纯。酶学性质分析表明，重组木聚糖酶最适温度为40 ℃，最适pH值为5.0，在酸性和常温条件下具有良好的稳定性。 相似文献
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Chen YT Hsu LH Huang IP Tsai TC Lee GC Shaw JF 《Journal of agricultural and food chemistry》2007,55(3):714-722
A chitinase cDNA clone (CpCHI, 1002 bp) was isolated from papaya fruit, which encoded a 275 amino acid protein containing a 28 amino acid signal peptide in the N-terminal end. The predicted molecular mass of the mature protein was 26.2 kDa, and its pI value was 6.32. On the basis of its amino acid sequence homology with other plant chitinases, it was classified as a class IV chitinase. An active recombinant CpCHI enzyme was overexpressed in Escherichia coli. The purified recombinant papaya chitinase showed an optimal reaction temperature at 30 degrees C and a broad optimal pH ranging from 5.0 to 9.0. The recombinant enzyme was quite stable, retaining >64% activity for 3 weeks at 30 degrees C. The spore germination of Alternaria brassicicola could be completely inhibited by a 76 nM level of recombinant CpCHI. Recombinant CpCHI also showed antibacterial activity in which 50% of E. coli was inhibited by a 2.5 microM concentration of the enzyme. 相似文献
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大丽轮枝菌蛋白激发子PevD1诱导的烟草对烟草花叶病毒(TMV)系统获得性抗性及其分子机制 总被引：3，自引：0，他引：3
从大丽轮枝菌(Verticillium dahliae)的胞外分泌物中分离到一种蛋白激发子PevD1 (UniProtKB accession No.P86840).为了明确该蛋白激发子的特性以及诱导植物抗病的机制,本研究在大肠杆菌(Escherichia coli)中表达了重组蛋白6His-PevD1.该重组蛋白激发子可以引起烟草(Nicotiana tabacum cv.Samsun-NN)悬浮细胞死亡,提高烟草植株对烟草花叶病毒(TMV)的系统获得抗性(SAR),枯斑抑制率最高可达46.64％.重组蛋白激发子处理后的烟草叶片中的苯丙氨酸解氨酶(PAL)、多酚氧化酶(PPO)和过氧化物酶(POD)活性均有大幅度提高.处理后144 h PAL活性最大,是对照的3.3倍;处理后120 h,PPO和POD活性分别增加236.8％和204.6％.PevD1可以诱导抗性相关基因酸性病程相关基因1(acid pathogenesis-related gene 1,PR1-a)、碱性病程相关基因1(basic pathogenesis-related gene 1,PR1-b)、病程相关基因非表达子1(nonexpressor ofpathogenesis-related gene 1,NPR1)和苯丙氨酸解氨酶基因(phenylalanine ammonia lyase gene,PAL)的表达.研究表明,防御相关酶的活性提高和抗病相关基因的诱导表达是PevD1诱导烟草产生系统性抗性的主要机制. 相似文献
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Conesa C Sánchez L Pérez MD Calvo M 《Journal of agricultural and food chemistry》2007,55(12):4848-4853
Thermal denaturation of recombinant human lactoferrin from transgenic rice with different degrees of iron saturation has been studied by differential scanning calorimetry. The maximum temperature, enthalpy change, and activation energy of denaturation were higher when recombinant lactoferrin was more saturated with iron, indicating an increase in the stability of the protein structure. Maximum temperature and activation energy values for apo- and holo-lactoferrins were practically identical to those reported for the same forms of lactoferrin from human milk, which indicates a similar thermal stability. However, the value of enthalpy change for denaturation of the recombinant lactoferrin was 2.5-3-fold lower than that found for the human milk protein. This finding may reflect the influence that the different glycosylation pattern may have in the relationship between lactoferrin domains. Denaturation of recombinant lactoferrin in milk was compared with denaturation in phosphate buffer, and results indicated that the protein was more heat-sensitive when treated in milk than in buffer. 相似文献
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Eero Varis Leena Pietilä Kauko Koikkalainen 《Acta Agriculturae Scandinavica, Section B - Plant Soil Science》2013,63(1):41-48
Abstract In 1987, a potato research project called “Minimized use of chemical inputs in potato production” was started in all five Scandinavian countries. In this paper, the results of one field trial series carried out at the Potato Research Institute, Lammi, Finland, during the years 1987–90 are reported. The main plots in a split-plot designed trial series consisted of three cropping systems: conventional, integrated and organic. The subplots included three cultivars differing especially in their late blight (Phythophtora infestans, (Mont.) de Bary) resistance: Bintje, Record and Matilda. Canopy measurements showed differences that can be attributed to different nitrogen supply in decreasing order from conventional to integrated to organic system. The trial sites were very heavily infested with potato scab, resulting in a very low percentage of I-class yield in susceptible cultivars Bintje and Matilda. Late blight was a serious problem in organically grown Bintje, as expected. Total yields in the integrated and organic systems were 10% and 36% lower, respectively, than in the conventional system. There was an interaction between cropping system and cultivar in favour of Bintje and the conventional system and Record in the organic system. The percentage of I-class yield was lowest in the conventional system. Some of the quality characteristics were slightly improved in the integrated and/or organic systems. Storage losses, caused mainly by tuber blight, were high in organically grown potatoes. There were no large differences in production costs between the cropping systems. The main determinants of the unit production cost of potatoes were total yield and yield of I-class potatoes. The average unit costs were 1.76 FIM kg?1 in the conventional, 1.68 FIM kg?1 in the integrated and 2.36 FIM kg?1 in the organic system. Record showed the lowest unit production costs in all systems ?1.33, 1.37 and 1.80 FIM kg?1, respectively. 相似文献
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The amino acid composition and physicochemical and functional properties of hemp (Cannabis sativa L.) protein isolate (HPI) were evaluated and compared with those of soy protein isolate (SPI). Edestin, a kind of hexameric legumin, was the major protein component. HPI had similar or higher levels of essential amino acids (except lysine), in comparison to those amino acids of SPI. The essential amino acids in HPI (except lysine and sulfur-containing amino acids) are sufficient for the FAO/WHO suggested requirements for 2-5 year old children. The protein solubility (PS) of HPI was lower than that of SPI at pH less than 8.0 but similar at above pH 8.0. HPI contained much higher free sulfhydryl (SH) content than SPI. Differential scanning calorimetry analysis showed that HPI had only one endothermic peak with denaturation temperature (T(d)) of about 95.0 degrees C, attributed to the edestin component. The T(d) of the endotherm was nearly unaffected by 20-40 mM sodium dodecyl sulfate but significantly decreased by 20 mM dithiothreitol (P < 0.05). The emulsifying activity index, emulsion stability index, and water-holding capacity of HPI were much lower than those of SPI, and the fat adsorption capacity was similar. The data suggest that HPI can be used as a valuable source of nutrition for infants and children but has poor functional properties when compared with SPI. The poor functional properties of HPI have been largely attributed to the formation of covalent disulfide bonds between individual proteins and subsequent aggregation at neutral or acidic pH, due to its high free sulfhydryl content from sulfur-containing amino acids. 相似文献
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A putative thermostable pectinmethylesterase (TSPME) protein of 36 kDa was isolated from heat-treated citrus finisher pulp. After purification and partial sequencing of the protein, a reverse genetic approach was used to obtain the complete genomic sequence of a new pectinmethylesterase (PME) gene, CsPME4, from Citrus sinensis (L.) Osb. cv. Valencia. The CsPME4 gene contained two exons of 1203 and 690 bp interrupted by a single positionally conserved intron of 1230 bp. A full-length CsPME4 cDNA clone amplified from Valencia orange juice vesicles shared 98% identity with the genomic clone. The encoded protein of the full-length CsPME4 cDNA shared 66 and 39% amino acid identity with the full-length encoded proteins of the citrus PME, CsPME1, and CsPME3, respectively, whereas the predicted mature protein of CsPME4 shared 80 and 61% identity with the predicted mature proteins of CsPME1 and CsPME3, respectively. Southern analysis demonstrated that CsPME4 was present in at least two copies in the Valencia orange genome. Northern analysis revealed that CsPME4 mRNA was accumulated mainly in young and developing tissues of Valencia orange. Several approaches to express recombinant CsPME4 in different systems failed to obtain active protein. Further research will be necessary to successfully express the putative TSPME gene CsPME4 for biochemical characterization. 相似文献
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ω3 脂肪酸去饱和酶(fatty acid desaturase, FAD)能使藻类细胞产生一系列具有高附加值的ω3 脂肪酸。在已克隆到缺刻缘绿藻(Myrmecia incisa Reisigl)的ω3FAD 基因基础上,为进一步了解其功能,本研究首先利用反转录 PCR(RT-PCR)技术,克隆其开放阅读框(open reading frame, ORF)片段,然后亚克隆到穿梭表达载体 pYES2 中,以构建重组酵母表达载体 pY-ω3FAD;通过电穿孔法将该重组载体转入酿酒酵母(Saccharomyces cerevisiae)INVSc1 菌株中,经筛选与序列验证得到含有 pY-ω3FAD 重组质粒的酵母转化株。在 5℃,添加底物亚麻酸及半乳糖诱导表达,连续培养 72 h,经脂肪酸甲酯的气相色谱分析及气相色谱 - 质谱联用证明,转目的基因的酵母能将外源添加的亚油酸在 15 位脱氢生成α- 亚麻酸,表明ω3FAD具有Δ15 脂肪酸去饱和作用的功能。在不同温度条件下诱导培养时,气相色谱结果显示,在 30℃培养的转基因酵母中没有检测到α- 亚麻酸;但在不高于 25℃培养的转基因酵母中,发现ω3FAD 能将外源添加的底物去饱和为α- 亚麻酸,且随着温度的降低,其去饱和能力增强,5℃时的底物转化效率达到29.73%。将转目的基因酵母在 5℃温度下诱导培养不同时间,结果显示,随着培养时间的增加,LA(linoleic acid,亚油酸)转化为α- 亚麻酸的效率也提高,培养 4 d 时其转化效率达到 38.86%。该研究结果提示,缺刻缘绿藻ω3FAD 基因编码的酶蛋白为一个低温诱导酶。缺刻缘绿藻ω3FAD 基因之所以能在酵母细胞中被低温诱导表达,可能因为后者存在一个低温诱导的脂肪酸去饱和系统。 相似文献
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Chen JJ Chen GH Hsu HC Li SS Chen CS 《Journal of agricultural and food chemistry》2004,52(8):2256-2261
It was shown previously that a bacterially expressed mungbean defensin VrCRP exhibited both antifungal and insecticidal activities. To isolate this protein in a large quantity for its characterization, the defensin cDNA was expressed in Pichia pastoris and the recombinant defensin (rVrD1) was purified. The recombinant VrD1 was shown to inhibit the growth of fungi such as Fusarium oxysporum, Pyricularia oryza, Rhizoctonia solani, and Trichophyton rubrum and development of bruchid larva. The protein also inhibits in vitro protein synthesis. These biological activities are similar to that of the bacterially expressed defensin. Functional expression of VrD1 in Pichia pastoris provides a highly feasible system to study the structure-function relationship of VrD1 using the mutagenesis approach. 相似文献
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为进一步开发红叶李资源,筛选其活性成分,通过比较水煮沸、醇回流、超声、微波、闪式、超临界CO_2(SFE-CO_2)、复合酶酶解等提取方法对红叶李花中总黄酮含量的影响和对α-葡萄糖苷酶活性的抑制效果,确定最佳提取方法,并通过单因素试验和响应面法优选提取工艺。结果表明,复合酶酶解联合SFE-CO_2萃取工艺提取效率和生物活性最佳,SFE-CO_2萃取的总黄酮对α-葡萄糖苷酶抑制率达到96.09%,IC50为12.16μg·m L-1。最佳提取工艺为:酶解温度30℃,酶解时间3.5 h,酶用量0.10%,萃取压力30 MPa,乙醇浓度85%,萃取温度45℃,萃取时间60 min。此条件下的总黄酮得率为11.55%。本研究结果为红叶李花中总黄酮的开发与利用提供了技术参考。 相似文献
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Helianthinin, the main storage protein of sunflowers, has low water solubility and does not form a gel when heated; this behavior is different from other 11S globulins and limits its food applications. To understand this particular behavior, changes on helianthinin association-dissociation state induced by modifications in pH and ionic strength were analyzed. The influence of these different medium conditions on its thermal stability and tendency to form aggregates was also studied. Helianthinin behavior at different pH values and ionic strengths is similar to other 11S globulins except that it remains in a trimeric form at pH 11. Helianthinin thermal stability is higher than other 11S globulins but is lower than oat 11S globulin. Alkaline pH produces a 10 degrees C decrease of its denaturation temperature and also of the cooperativity of denaturation process, but it does not affect the denaturation activation energy. The decrease in thermal stability with the pH increase is also manifested by its tendency to form aggregates by SH/SS interchange reactions. When thermal treatments at alkaline pH are performed, all helianthinin subunits form aggregates, characterized by a higher proportion of beta-polypeptides than alpha-polypeptides, which is an indication that aggregation is accompanied by dissociation. Treatments at 80 degrees C are sufficient to induce aggregation but not to produce denaturation, and in these conditions hexameric forms remain after the treatment. 相似文献
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对乳糖诱导工程菌株BL-pET-hBD3-Bra表达的人β防御素3和植物des-pGlu1-Brazzein融合蛋白进行了纯化和活性分析。并对工程菌株的乳糖诱导表达条件进行了优化。对目的蛋白的活性分析表明,hBD3-Bra融合蛋白有一定的甜味,但是杀菌活性很弱,经凝血酶切割后,重组hBD3有明显的抑菌活性,des-pGlu1-Brazzein的甜度大约为蔗糖甜度的600倍。乳糖浓度、诱导时间和诱导温度对菌株生长和目的蛋白表达的试验结果显示：高浓度乳糖对菌株生长有抑制作用（P<0.01）,对目的蛋白的表达无显著影响(P>0.05);时间延长对于菌株生长有利（P<0.01）,对目的蛋白的表达无显著影响（P>0.05);温度对菌株生长和目的蛋白的表达均有显著影响（P<0.01）。进一步的研究表明,菌株在30℃-32℃生长,在30℃诱导最优,乳糖和IPTG的诱导结果无显著差异（P>0.05)。 相似文献
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Orlien V Risbo J Andersen ML Skibsted LH 《Journal of agricultural and food chemistry》2003,51(1):211-217
The thermal behavior of fresh tuna muscle, rehydrated freeze-dried tuna muscle, and tuna sarcoplasmic protein fraction was studied by three types of differential scanning calorimetry (DSC): conventional DSC, alternating DSC, and sensitive micro-DSC. The relationship between glass transition temperature, T(g), and water content was established. Only a low-temperature glass transition was detected for fresh tuna and freeze-dried tuna rehydrated to high water contents, whereas for sarcoplasmic protein fraction both a low-temperature and an apparent high-temperature glass transition were detected for samples of high water content. Construction of the supplemented state diagrams for whole tuna muscle and for tuna sarcoplasmic protein fraction confirmed the low-temperature transition to be glass transition of the maximally freeze-dehydrated phase. The apparent upper transition of sarcoplasmic protein fraction was shown not to be a glass transition but rather to originate from the onset of melting of ice, and the temperature of this event should be denoted T(m)'. The glass transition temperature and the concentration of the maximally freeze dehydrated tuna muscle are -74 degrees C and 79% (w/w), respectively. 相似文献
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Wang F Ning Z Lan D Liu Y Yang B Wang Y 《Journal of agricultural and food chemistry》2012,60(1):165-172
The effects of various factors on the activity and conformation of recombinant leucine aminopeptidase II (rLAP II) from Bacillus stearothermophilus and its potential utilization in the hydrolysis of anchovy proteins were investigated. The optimal temperature and pH of rLAP II were 55 °C and 8.0 in phosphate buffer, and its activity was strongly stimulated by Co(2+). Conformational studies indicated that maintaining the α-helical structure had a critical effect on rLAP II activity. rLAP II was used to hydrolyze anchovy proteins, and it exhibited high specificity for peptides with molecular weight between 6000 and 1000 Da and positive coordination with endogenous enzymes and commercial Flavourzyme. Its use will enhance protein hydrolysis in species of aquatic animals. rLAP II could potentially be used to remove bitterness in the protein hydrolysis industry. 相似文献
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重组海参溶菌酶C端基因(SjLys-C)的可溶性表达和抑菌活性分析 总被引：1，自引：0，他引：1
为进一步研究海参(Stichopus japonicus)溶菌酶基因(Sjys)(Genbank登录号:EF036468)中不司片段表达产物的生物特性,本研究通过对其cDNA片段的分析,发现C端基因区域所对应的蛋白质序列中含有非酶活性.根据已知的海参溶菌酶的cDNA序列,设计山含有Nco Ⅰ和EcoR Ⅰ酶切位点的特异性引物,从新鲜的海参肠中提取总RNA,以其为模板利用RT-PCR扩增出长度为259 bp的溶菌酶C端(SjLys-C)基因.将该目的基因连接到pET-32a(+)载体上,构建重组质粒pET-32a(+)-SjLys-C,再转化至大肠杆菌(Escherichia coli)Rosetta(DE3)pLysS,成功地构建了重组蛋白SjLys-C的基因工程菌.利用该工程菌诱导发酵,结果显示它能高效表达出26 kD左右的重组蚩白SjLys-C.经过Western blot分析,该重组蛋白在26 kD左右能够与Penta-His抗体发生特异性免疫反应.对纯化的重组蛋白SjLys-C进行了抑菌特性的分析,结果发现它对溶壁微球菌(Micrococcus lysodeikticus)和副溶血弧菌(Vibrio parahae molytic us)有较高的抑菌活性.此外,将该重组蛋白经100℃、40 min处理后,其抑菌能力提高了5％～21％.研究结果表明,重组蛋白SjLys-C基因工程菌能够制备出具有可溶性的、并具有抑菌活性的重组蛋白SjLys-C,在农业和医药等行业中有潜在应用和开发价值. 相似文献