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1.
Aseries of in vitro trials was carried out to examine the capacity of eight proteolytic enxymes,which are either of bacterial or of fungal origins,and their combinations with a-deglycosidase in denaturing the activity of lectin and trypsin inhibitors in Paseolus vulgris,seed type “processor”,under the similar conditions to those of the gut.Znzymes,P3 and P4,were the most effective of hydrolyisis of trypsin inhibitory activity.After two hours incubation,trypsin inhibitory activity was reduced to 50 and 40% of the original value by P3 and P4 respectively.The rests of enzymes had little effects.Ompared with trypsin inhibitors,lectin was more resistant to hydrolysis.Only P4 reduced it by 26% of the original value.Pre-incubation with α-deglycosidase at its optimum conditions for one hour had no significant benefits for the tested proteases. 相似文献
2.
Middlebrook WR 《Science (New York, N.Y.)》1959,130(3376):621-622
Subtilisin, as well as trypsin and chymotrypsin, splits myosin into meromyosin-like components. Examination of the N- and C-terminal residues of the L-meromyosin-like products suggests that all three proteases produce identical L-meromyosins. It is proposed that the role of the enzymes is to break secondary bonds. 相似文献
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旨在研究不同抑制剂和激活剂对梨星毛虫Illiberis pruni中肠蛋白酶活性的影响。利用生化技术分别测定梨星毛虫幼虫不同龄期的4种中肠蛋白酶（总蛋白酶、强碱性胰蛋白酶、弱碱性胰蛋白酶和胰凝乳蛋白酶）活性,进而在最适龄期（4龄幼虫）测定蛋白酶激活剂（EDTA,MgCl2,EGTA,CaCl2）和抑制剂（PMSF,TPCK,STI,TLCK,IAA,DTT）对梨星毛虫中肠蛋白酶活性的影响。结果表明：梨星毛虫幼虫中肠总蛋白酶、强碱性胰蛋白酶、弱碱性胰蛋白酶、胰凝乳蛋白酶均在4龄具有最高酶活性。所有试剂均对总蛋白酶有激活作用;5 mmol/L CaCl2对强碱性胰蛋白酶抑制作用最高;对弱碱性胰蛋白酶有抑制作用的仅有5 mmol/L DTT;对胰凝乳蛋白酶抑制效果最佳的为10 mmol/L EGTA。所筛选的对梨星毛虫主要中肠蛋白酶具有抑制作用的抑制剂,对以昆虫中肠蛋白酶为靶标的绿色害虫防控技术的开发具有参考价值。 相似文献
4.
Identification of a zinc finger protein that binds to the sterol regulatory element 总被引：36，自引：0，他引：36
T B Rajavashisth A K Taylor A Andalibi K L Svenson A J Lusis 《Science (New York, N.Y.)》1989,245(4918):640-643
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Lectin activation in Giardia lamblia by host protease: a novel host-parasite interaction 总被引：9，自引：0，他引：9
A lectin in Giardia lamblia was activated by secretions from the human duodenum, the environment where the parasite lives. Incubation of the secretions with trypsin inhibitors prevented the appearance of lectin activity, implicating proteases as the activating agent. Accordingly, lectin activation was also produced by crystalline trypsin and Pronase; other proteases tested were ineffective. When activated, the lectin agglutinated intestinal cells to which the parasite adheres in vivo. The lectin was most specific to mannose-6-phosphate and apparently was bound to the plasma membrane. Activation of a parasite lectin by a host protease represents a novel mechanism of host-parasite interaction and may contribute to the affinity of Giardia lamblia to the infection site. 相似文献
7.
不同砧木嫁接对薄皮甜瓜成熟期品质、香气合成相关酶活性及基因表达的影响 总被引：2，自引：0，他引：2
【目的】明确不同砧木嫁接对薄皮甜瓜成熟期品质、主要香气组分和含量及相关酶活性与基因表达的影响。【方法】以薄皮甜瓜‘玉美人’为接穗,白籽南瓜‘圣砧1号’(G1)、‘甜砧2号’(G2) 和厚皮甜瓜‘PG22HF1’(G3) 为砧木,测定成熟果实的相关品质及香气合成关键酶活性,并对醇脱氢酶（alcohol dehydrogenase, ADH）和醇酰基转移酶（alcohol acyltransferase, AAT）的基因表达进行实时荧光定量PCR分析。【结果】3种砧木嫁接不同程度地延迟了果实成熟,表现为果实硬度大,果皮颜色退绿慢,可溶性固形物含量低,G2比自根果实延后2 d,而G1和G3延后程度更大。G2砧木嫁接后显著提高了成熟甜瓜果实中非乙酸酯类种类和含量以及乙酸乙酯等主要酯类的含量,其非乙酸酯类含量是花后相同天数自根果实的1.5倍;而其它两个砧木嫁接后显著降低了主要酯类的含量,且3种砧木嫁接果实中均检测到自根果实中没有的草酸烯丙基异己酯。对于成熟一致的果实,嫁接没有显著降低香气合成相关酶活性,而且G2还提高了脂氧合酶（lipoxygenase, LOX）、ADH和AAT的活性,但是,嫁接抑制了香气合成关键酶的基因表达。【结论】不同砧木对成熟果实品质影响不同。‘甜砧2号’利于提高果实品质,其它两个砧木降低了相关品质。嫁接一方面是通过延迟果实成熟而影响果实品质和香气合成相关酶的活性,另一方面,从转录水平降低了香气合成相关酶基因的表达,最终影响果实的香气成分和品质。 相似文献
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番茄不同抗性品种响应B型烟粉虱胁迫的生理特性 总被引：1，自引：0，他引：1
【目的】明确在B型烟粉虱（Bemisia tabaci）胁迫下,番茄抗虫品种和感虫品种叶片的生理特性变化,为生产上选育和推广番茄抗烟粉虱品种提供参考。【方法】在人工气候室内,以番茄抗虫品种红圣女（Hongshengnv,HSN）和感虫品种黄圣果（Huangshengguo,HSG）为研究材料,通过非选择性试验,比较研究在B型烟粉虱胁迫下,叶片的次生代谢物质(蔗糖酯、没食子酸、咖啡酸、阿魏酸、苯甲酸、水杨酸、木质素）含量、防御酶(过氧化物酶（POD）、过氧化氢酶（CAT）、多酚氧化酶（PPO）、脂氧合酶（LOX）)活性、胰蛋白酶抑制剂（TI）活性、光合参数值（Fv/Fm、Fv/Fo）、活性氧（H2O2含量、 产生速率）、丙二醛（MDA）含量、细胞膜电解质渗出率（EC）的变化。【结果】红圣女与黄圣果的蔗糖酯、酚酸、木质素、H2O2和丙二醛含量以及Fv/Fo值、防御酶和胰蛋白酶抑制剂活性均存在显著差异（P＜0.05）;而两个品种的Fv/Fm、 产生速率、细胞膜电解质渗出率没有显著差异（P＞0.05)。两个品种对B型烟粉虱胁迫的响应差异明显,胁迫9 h后,叶片的蔗糖酯、酚酸、木质素含量和防御酶活性均升高,且红圣女的升高程度强于黄圣果;叶片发生光抑制现象,光合参数值和胰蛋白酶抑制剂活性均下降,红圣女的下降程度小于黄圣果;同时叶片产生大量活性氧,丙二醛积累、细胞膜电解质渗出率上升,黄圣果的细胞受损伤程度高于红圣女。【结论】番茄不同抗性品种对B型烟粉虱胁迫的响应存在差异性,抗虫品种响应次生代谢物质含量和防御酶活性的变化更强烈;感虫品种响应光合参数、活性氧、细胞膜脂过氧化和胰蛋白酶抑制剂活性的变化更强烈。 相似文献
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Some quantum yields for the destruction of amino acids have been determined. The inactivation of the enzymes hymotrypsin, lysozyme, ribonuclease, and trypsin by ultraviolet light can be accounted for quantitatively by summing the products of (i) the probability that light is absorbed by a given amino acid residue, epsilon(4), and (ii) the probability that absorbed light induces a chemical change, with a quantum efficiency phi(4), in the residue. The principal residues involved are cystyl and tryptophanyl. Peptide bond rupture is not important. Analysis of inactivated enzymes verifies the assumption of the existence of several inactivation mechanisms. 相似文献
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High-resolution carbon-13 nuclear magnetic resonance (NMR) spectra of enzyme-inhibitor and enzyme-substrate complexes provide detailed structural and stereochemical information on the mechanism of enzyme action. The proteases trypsin and papain are shown to form tetrahedrally coordinated complexes and acyl derivatives with a variety of compounds artificially enriched at the site or sites of interest. These results are compared with the structural information derived from x-ray diffraction. Detailed NMR studies have provided a clearer picture of the ionization state of the residues participating in enzyme-catalyzed processes than other more classical techniques. The dynamics of enzymic catalysis can be observed at sub-zero temperatures by a combination of cryoenzymology and carbon-13 NMR spectroscopy. With these powerful techniques, transient, covalently bound intermediates in enzyme-catalyzed reactions can be detected and their structures rigorously assigned. 相似文献
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根据已报道具韧皮部组织特异性的笋瓜韧皮部蛋白2（PP2）基因序列设计引物,以山西本地种笋瓜叶片基因组DNA为模板,用PCR法扩增得到了长度为966bp的PP2基因启动子片段,克隆入pUCm—T载体后,经鉴定获得了新的重组质粒pUCm—PSP,测序和序列分析表明与两个已报道的片段分别有95％和99％的同源性,推测具有相似的启动子功能。分别用限制性内切酶PstⅠ和BglfⅡ双酶切重组质粒pUCm—PSP和由CaMV35S组成型启动子驱动GFP报告基因的双元植物表达载体pCAMBIA1302,分别回收pUCm—PSP重组质粒中的PSP小片段和pCAMBIA1302植物表达载体中去掉GFP报告基因上游CaMV35S组成型启动子的大片段,经连接、转化和鉴定后,构建了由PSP驱动报告基因GFP的新型植物表达载体pHZ03。利用细胞感受态法将新植物表达载体分别导入根癌农杆菌EHA105、GV3101、LBA4404和发根农杆菌Ri15834中,为进一步研究其表达功能奠定了基础。 相似文献
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乳源降血压七肽基因在毕赤酵母中的表达研究 总被引：1，自引：0，他引：1
利用基因工程技术在毕赤酵母中高效表达乳源抗高血压七肽,为大规模生产抗高血压肽奠定基础。根据毕赤酵母密码子偏爱性,人工合成了具有较高活性的抗高血压七肽串联基因序列。将串联基因克隆至表达载体pPIC9上,并转化毕赤酵母GS115,经PCR检测获得2株重组菌株。重组菌经甲醇诱导,表达的分泌蛋白经胰蛋白酶酶解,测定酶解产物抑制ACE酶活性。结果表明,表达蛋白的胰蛋白酶酶解产物抑制ACE酶活性达到65.12%。IC50值为0.0203 mg.mL-1。研究成功合成了串联的13拷贝抗血压七肽基因,并实现了其在毕赤酵母中的高效表达,表达蛋白的胰蛋白酶酶解产物具有抗高血压肽活性。 相似文献
13.
An insulin-stimulated protein kinase similar to yeast kinases involved in cell cycle control 总被引：67，自引：0，他引：67
T G Boulton G D Yancopoulos J S Gregory C Slaughter C Moomaw J Hsu M H Cobb 《Science (New York, N.Y.)》1990,249(4964):64-67
A protein kinase characterized by its ability to phosphorylate microtubule-associated protein-2 (MAP2), is thought to be an early intermediate in an insulin-stimulated phosphorylation cascade and in a variety of other mammalian cell responses to extracellular signals. A complementary DNA that encodes this protein serine-threonine kinase has been cloned, and the protein designated extracellular signal-regulated kinase 1 (ERK1). ERK1 has striking similarity to two protein kinases, KSS1 and FUS3, from yeast. The yeast kinases function in an antagonistic manner to regulate the cell cycle in response to mating factors. Thus, ERK1 and the two yeast kinases constitute a family of evolutionarily conserved enzymes involved in regulating the response of eukaryotic cells to extracellular signals. 相似文献
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为了充分利用骨资源,以鲤鱼头和鱼骨为原料,用无水乙醚、异丙醇、乙醇三种有机溶剂对其进行脱脂处理,以脱脂率为指标采用三因素三水平正交试验,确定最佳脱脂方法;利用胰蛋白酶、木瓜蛋白酶、中性蛋白酶对脱脂后的鱼骨粉进行水解,以水解度为测定指标,采用四因素三水平正交试验确定最佳酶解条件。结果表明,采用异丙醇在30℃条件下萃取120 min的脱脂效果最好;胰蛋白酶在底物浓度为1∶15,酶用量为5400 U.g-1,酶解4 h可获得最高水解度(19.20%)。 相似文献
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用DEAE Sepharose Fast Flow离子交换层析从中草药蒲黄中分离纯化一种纤维蛋白溶解酶,用纤维蛋白板检测分离后组分的纤溶蛋白活性,天然电泳检测分离效果,分离后得到了比活力为25.29的单一组分,SDS电泳确定该组分的表观分子量为31 000 D,同时比较了不同蛋白酶抑制剂对该组分的抑制作用。结果表明:该组分的纤维蛋白水解酶活性被PMSF、亮抑肽素、抑肽酶、大豆胰蛋白酶抑制剂以及苯甲脒强烈抑制,表明该粗提物中的蛋白酶属于丝氨酸蛋白酶家族。 相似文献
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Studies of inositol phospholipid-specific phospholipase C 总被引：65，自引：0，他引：65
Inositol phospholipid-specific phospholipase C is the enzyme that generates phosphoinositide-derived messenger molecules. Mammalian cells contain at least five immunologically distinct phospholipase C enzymes that appear to be separate gene products. Complete amino acid sequences of four of these isozymes have been established. The overall sequence similarity is surprisingly low for enzymes catalyzing the same chemical reaction: three of them show limited amino acid sequence similarity to each other in two narrow regions, and the fourth enzyme is completely different. The diversity in primary structure together with different regional and cellular expression of the isozymes suggests that each isozyme has a defined function in processing the physiological response of different cell types to a variety of external stimuli and that each is regulated differently. 相似文献
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１ Ｉｎｔｒｏｄｕｃｔｉｏｎ Ａｌｔｈｏｕｇｈｔｈｅｈｉｇｈｐｒｏｔｅｉｎｃｏｎｔｅｎｔｏｆｓｏｙｂｅａｎｓｅｅｄｓｍａｋｅｔｈｅｍａｔｔｒａｃｔｉｖｅｃａｎｄｉｄａｔｅｓａｓ－ｓｏｕｒｃｅｓｏｆｄｉｅｔａｒｙｎｉｔｒｏｇｅｎｆｏｒｍｏｎｏｇａｃｔ... 相似文献
19.
高剂量铜对仔猪生长性能的影响及作用机理探讨 总被引：4，自引：0，他引：4
10 8头杜长大仔猪 [体重为 (15 8± 1 34)kg]按饲养试验要求分为 2组 ,分别饲喂添加 5mg/kg和 2 5 0mg/kg铜 (CuSO4形式 )的相同饲粮 ,研究高剂量铜对仔猪生长性能的影响及其机理探讨。试验结果表明 :添加高铜使仔猪平均日增重提高了 13 0 4 % (P <0 0 1) ,平均日采食量提高 9 91% (P <0 0 1) ;饲料粗脂肪的表观消化率提高了10 0 1% (P <0 0 5 ) ;高铜使十二指肠内容物中淀粉酶和脂肪酶活性分别提高 15 6 6 % (P <0 0 5 )、12 5 3% (P <0 0 5 ) ,胰脏糜蛋白酶活性降低 11 6 9% (P <0 0 5 ) ;血清胃泌素浓度提高 2 9 2 5 % (P <0 0 1) ;血清SOD活性提高了 36 94 % (P <0 0 1)。 相似文献
20.
yczou@hotmail.com 《勤云标准版测试》2006,(5)
澳大利亚小麦品种Sunco成株期对中国条锈病小种条中32(CY32)表现高抗-免疫,而小麦品种川育12则表现为高感。利用Sunco/川育12的双单倍体(DH)群体对Sunco进行抗条锈病遗传研究,结果表明,品种Sunco可能具有持久抗性,抗性是由一对主效基因和两对微效基因联合作用的结果;主效基因的抗性反应为抗-中抗(R-MR),微效基因单独存在作用不明显,但与主效基因结合起来会加强抗条锈病能力。同时对微效多基因的持久抗性利用作了初步探讨。 相似文献