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1.
用PCR 方法从芝田硫化叶菌中扩增了编码一种新酶,即麦芽寡糖基海藻糖合酶( MTSase) 的基因,扩增的2-2kb DNA 插入到原核表达载体pBV220 中,构建成重组质粒pSBGT1 。pSBGT1 中MTSase 基因在大肠杆菌中得到表达。SDSPAGE 分析表达产物MTSase蛋白的分子量约为74kDa ,同核苷酸序列测定所推导的值相符。表达产物占细胞总蛋白约4-4 % 。pSBGT1 产生的重组酶作用于淀粉部分水解物,使DE 值降低,得到非还原糖或低还原糖。  相似文献   

2.
吲哚3甘油磷酸合酶(IGS,indole3glycerolphosphatesynthase,EC4.1.1.48)在色氨酸与吲哚乙酸的生物合成途径中,催化生成吲哚3甘油磷酸。研究该基因的表达调控,对于阐明高等植物是如何调控色氨酸及生长素合成是十分重要的。利用已克隆的IGScDNA,构建了谷胱甘肽转移酶(GST,glutathioneStransferase,EC2.5.1.18)与吲哚3甘油磷酸合酶融合蛋白的表达质粒,并将其导入到在异丙基βD硫代半乳糖苷(IPTG)诱导下能高效表达的IGS基因缺陷菌株trpC9800λKC大肠杆菌中。高表达的融合蛋白通过谷胱甘肽琼脂糖(glutathioneagarose)亲和层析和SDS聚丙烯酰胺凝胶电泳纯化后,用以免疫兔子制备抗血清。免疫印迹法分析表明拟南芥(Arabidopsisthaliana(L.)Heynh.)四种常用生态型只合成一种分子量约为40kD的吲哚3甘油磷酸合酶蛋白。在Ag+、紫外线等逆境条件下,IGS含量都有较大幅度的增加,这说明IGS可能与植物的防御反应紧密相关。  相似文献   

3.
将大鼠酰胺化酶的信号肽及前导肽编码序列引入昆虫核多角体病毒转移表达载体,构建PABChGRF(Gly)、PABCIGFI融合基因的昆虫细胞分泌表达质粒pBacPAG2、pBacPAI,并与经修饰的银纹夜蛾核多角体病毒BacPAK6线性化DNA共转染秋粘虫细胞Sf21,通过同源重组、筛选和鉴定,得到它们的重组病毒BacPAG、BacPAI。将重组病毒感染Sf21细胞,PABChGRF(Gly)和PABCIGFI均得到有效外泌表达,表达产物通过IgGSepharose柱可获得快速纯化。  相似文献   

4.
当酵母细胞处于高渗压环境时,甘油被诱导合成以提高其胞内渗透压,这一过程受HOG途径的调控。GPD1基因为HOG途径的重要靶基因,高效表达使胞内3磷酸甘油脱氢酶酶活水平提高可极大地提高甘油的产量。本研究将产甘油假丝酵母(Candidaglycerologenesis)染色体DNA经Sau3AI部分酶解后的5~10kbDNA片段与经BamHI线性化及CIP处理过的酵母大肠杆菌穿梭质粒YEp51连接,以大肠杆菌DH5α为受体,构建产甘油假丝酵母的染色体基因文库。通过遗传互补法,在含50g/L氯化钠的培养基上筛选出15个转化子,对转化子0601进行了进一步鉴定,转化子0601所含质粒YEp0601带有YEp51的标记并可以消除Saccbaromycescerevisiae642菌株由于其GPD1,GPD2两基因的缺失突变而表现出的渗透压敏感性,表明已克隆到产甘油假丝酵母的编码胞浆3磷酸甘油脱氢酶的基因  相似文献   

5.
用蛋白质工程方法改变葡萄糖异构酶最适pH和最适温度   总被引:5,自引:2,他引:3  
用寡核苷酸诱导的定点突变方法构建了葡萄糖异构酶基因的突变体(N184D和A198C)。含突变体的重组质粒pTKD-GI1(N184D)和pTKD-GI2(A198c)在E.coliK38菌株中表达,用DEAE-Sepharose FF和Sephacryl S-300HR柱层析分离纯化突变酶。与野生型葡萄糖异构酶比较实验表明:(1)突变酶N184D的最适pH值下降了1个单位;等电点下降了0.6个单位  相似文献   

6.
枯草芽孢杆菌中性内切β-甘露聚糖酶的纯化及性质   总被引:14,自引:0,他引:14  
三草芽孢杆菌(Bacillus subtilis)BM9602产生的中性内切β-甘露聚糖酶(endo-β-1,4-D-mannan mannanohydrolaes,EC,3.2.1.78)经硫酸铵分级沉淀、DEAE-纤维素(DE22)离子交换柱层析,得到电泳纯的样品,提纯了45.5倍,收率为5.9%。用SDS-PAGE测得该酶的分子量为35kD。用PAGEIEF测得其等电点pⅠ为4.5。酶反应的  相似文献   

7.
编码大肠杆菌精氨酰t R N A 合成酶( Arg R S) 的基因arg S 被克隆到p M F T75 载体上。将此质粒转化的大肠杆菌 J M109( D E3) 中, 该转化子粗抽液的比活是宿主菌的2 500 倍。通过 D E A E Sepharose C L6 B Fast Flow 和 Blue Sepharose C L6 B两步柱层析在一天内即可将精氨酰t R N A 合成酶纯化至电泳一条带, 比活为36 000 u/mg , 总收率可达69 % 。与以前报道的 Arg R S的高表达质粒相比, 使用该重组质粒可以很方便地将昂贵的标记氨基酸高效地参入酶分子内。目前的研究结果表明,该新系统能够很方便地提供大量的更高比活的大肠杆菌精氨酰t R N A 合成酶以进行该酶的 N M R 和结晶学研究  相似文献   

8.
应用多聚酶链反应(PCR),直接从SIV感染的猴艾滋病(SAIDS)模型猴的外周血淋巴细胞总DNA中扩增出767bp的SIV核心蛋白P27基因片段。扩增产物经EcoRI及SalI双酶切后,克隆入相同酶切的表达质粒pBV220中,获得含SIV核心蛋白基因片段的重组质粒pBVSG,并进行DNA序列分析。用该重组质粒转化大肠杆菌DH5a经筛选、增殖及42℃温度诱导,SDS-PAGE表明外源基因表达蛋白含量占菌体总蛋白14.5%,Western-blot证实表达产物能被SIVP27单克隆抗体及SAIDS模型猴血清中特异性抗体识别。  相似文献   

9.
将含有鸡传染性支气管炎病毒 S1 基因c D N A 的重组转移质粒p S X I V V I+ X3 S1 . Holte 和p S X I V V I+ X3/4 S1 . Holte 分别与粉纹夜蛾核型多角体病毒 Tn N P V S V I- G D N A( O C C- ,gal+ ) 共转染草地夜蛾( Sf9) 细胞,经空斑纯化得到重组病毒 Tn N P V( X3) S1 . Holte O C C+ 和 Tn N P V( X3/4) S1 . Holte O C C+ 。将重组毒株分别感染 Tn5 B1 细胞,并进行 S D S P A G E 与 Westernblot 检测。结果表明, Tn N P V( X3/4) S1 . Holte O C C+ 在感染的细胞中高效表达了 S1 蛋白, S D S P A G E 凝胶薄层色谱分析结果显示,感染病毒后72 h S1 蛋白的表达量占细胞内总蛋白量的35 .8 % ,而 Tn N P V( X3) S1 . Holte O C C+ 感染的细胞内检测不出 S1 蛋白。经分析认为这一差异主要来自 S1 基因翻译起始位点及其附近的周围环境。  相似文献   

10.
当酵母细胞处于高渗压环境时,甘油被诱导合成以提高其胞内渗透压,这一过程受HOG途径的调控。GPD1基因为HOG途径的重要靶基因,高效表达使胞内3磷酸甘油脱氢酶酶活水平提高可极大地提高甘油的产量。本研究将产甘油假丝酵母(Candidaglycerologenesis)染色体DNA经Sau3AI部分酶解后的5~10kbDNA片段与经BamHI线性化及CIP处理过的酵母大肠杆菌穿梭质粒YEp51连接,以大肠杆菌DH5α为受体,构建产甘油假丝酵母的染色体基因文库。通过遗传互补法,在含50g/L氯化钠的培养基上筛选出15个转化子,对转化子0601进行了进一步鉴定,转化子0601所含质粒YEp0601带有YEp51的标记并可以消除Saccbaromycescerevisiae642菌株由于其GPD1,GPD2两基因的缺失突变而表现出的渗透压敏感性,表明已克隆到产甘油假丝酵母的编码胞浆3磷酸甘油脱氢酶的基因  相似文献   

11.
The 7 alpha-hydroxysteroid dehydrogenase (EC 1.1.1.159) gene from Escherichia coli HB101 was cloned and expressed in E. coli DH1. The hybrid plasmid pSD1, with a 2.8-kbp insert of chromosomal DNA at the BamHI site of pBR322, was subcloned into pUC19 to construct plasmid pSD3. The entire nucleotide sequence of an inserted PstI-BamHI fragment of plasmid pSD3 was determined by the dideoxy chain-termination method. Within this sequence, the mature enzyme protein-encoding sequence was found to start at a GTG initiation codon and to comprise 765 bp, as judged by comparison with the protein sequence. The deduced amino acid sequence of the enzyme indicated that the molecular weight is 26,778. The transformant of E. coli DH1 harboring pSD3 with a 1.8-kbp fragment showed about 200-fold-higher enzyme activity than the host. The enzyme was purified by a single chromatography step on DEAE-Toyopearl and obtained as crystals, with an activity yield of 39%. The purified enzyme was homogeneous, as judged by sodium dodecyl sulfate gel electrophoresis. The enzyme was most active at pH 8.5 and stable between pH 8 and 9. The enzyme was NAD+ dependent and had a pI of 4.3. The molecular mass was estimated to be 120 kDa by the gel filtration method and 28 kDa by electrophoresis, indicating that the enzyme exists in a tetrameric form.  相似文献   

12.
A pectin lyase (PNL;EC4.2.2.10) gene of Pseudomonas marginalis N6301 was cloned and expressed in Escherichia coli. We purified PNL from P. marginalis N6301 and determined N-terminal 33 amino acids sequence. From this sequence, we synthesized two oligonucleotide probes. From the analysis of Southern hybridization, 2. 1kb EcoRI-SmaI fragment from the chromosomal DNA of P. marginalis was found to hybridize with oligonucleotide probes. Then, we cloned the fragment into pUC119 vector and transformed into E. coli DH5 alpha. A plasmid thus obtained was designated as pPNL6301. E. coli DH5 alpha harboring pPNL6301 expressed PNL activity. The nucleotide sequence of pn1 gene in the plasmid pPNL6301 encoding PNL from P. marginalis N6301 was determined. The structural gene of pn1 consisted of 936 base pairs. An open reading frame that encodes a 34,103 dalton polypeptide composed of 312 amino acids was assigned. The molecular weight of the polypeptide predicted from the amino acid composition was close to that of PNL of P. marginalis N6301 determined. The nucleotide sequence of the 5'-flanking region of pn1 gene showed the presence of the consensus sequence of LexA binding site, Pribnow box and ribosome binding site as found in Escherichia coli. The amino acid sequence homology of PNLs and nucleotide sequence homology of pn1 gene between P. marginalis N6301 and E. carotovora Er were 60.8% and 57.2%, respectively.  相似文献   

13.
目的:克隆结核分枝杆菌分泌蛋白ESAT-6基因,并在大肠杆菌中进行表达和纯化。方法:用PCR方法从结核分枝杆菌H37Rv基因组扩增出ESAT-6基因片段,克隆至pMD18一T载体中,序列测定正确后,将其亚克隆到表达载体pGEX-4T-1并在大肠杆菌DH5α中表达,表达蛋白经SDS—PAGE及Westem—blot分析后,亲和层析法纯化蛋白。结果:成功克隆了ESAT-6基因,并对其在E.coli中进行了表达,SDS—PAGE及Western—blot分析表明表达产物正确。通过GST纯化系统获得34kD纯化蛋白,与文献报道相符。结论:成功获得了纯化的ESAT-6蛋白,为进一步研究ESAT-6蛋白的致病机理提供了实验依据。  相似文献   

14.
利用PCR方法从金黄色葡萄球菌TSTw基因组DNA中扩增出约700bp的DNA片段,将之克隆到pGEM7Zf(+)载体上并转化大肠杆菌 DH5α菌株。重组质粒的测序结果表明克隆到了seb基因,它含有717bp(不包括N端81bp的信号肽编码区),其核苷酸序列与文献报道完全一致。将其连接于表达载体7ZTS上,转化到大肠杆菌JM109(DE3)内。表达的SEB占总蛋白33.5%。   相似文献   

15.
目的:构建ADAMI0真核表达载体,为进一步研究其生物学功能打基础.方法:将人ADAM10的上下两部分基因片段(分别为全长基因的1 ~910bp和911 ~2 247bp片段),依次与真核表达载体pcDNA3.1相连,以大肠杆菌DH5α或BL21(DB)作为感受态宿主菌用于转化连接产物,拼接成全长的阳性克隆通过PCR、酶切和测序鉴定.结果:ADAM10下段基因与已正确连入上段的pcDNA3.1重组质粒拼接时,若用DH5α为感受态菌,则下半段出现碱基插入增加512bp,测序结果显示为ADAM10基因第1 531 bp~2 042 bp间的序列有紧邻的双份;若用BL21(DE3)为感受态,则无突变.结论:将ADAM10基因与pcDNA3.1真核表达载体依次拼接构建重组质粒时,以DH5α为宿主菌可出现基因序列增加的罕见突变,而以BL21(DE3)为宿主则无突变,由此成功构建ADAM10全长基因与pcDNA3.1的重组质粒.  相似文献   

16.
To identify, clone ,sequence and highly express the mature peptide gene of ApoA Ⅰ, total RNA was prepared from human fetal liver tissue. cDNA fragment encoding human ApoA Ⅰ was amplified by RT-PCR using specific primers, and then was inserted in pGEM-T vector. DNA sequencing indicates that the fragment is 729 base pairs in length and has 100% nucleotide homology with that of reported ApoA Ⅰ cDNA gene previously. The ApoA Ⅰ gene was cloned into pGEX 5X-1.The recombinant protein was expressed in E.coli DH5α, purified by glutathione-Sepharose 4B affinity chromatography and confirmed by SDS-PAGE. It was shown that the recombinant ApoA Ⅰ was expressed in E.coli, and the target protein amounted to 36% of total bacteria proteins. Cholesteryl ester transfer experiment showed that the recombinant ApoA Ⅰ was capable of promoting transfer of CE from HDL to LDL. Western blotting showed that the protein could react specifically with anti-ApoA Ⅰ antibodies.  相似文献   

17.
目的:利用大肠杆菌融合表达酮古龙酸菌细胞色素c氧化酶亚基Ⅱ(CcoⅡ)与谷胱甘肽S-转移酶(GST)并纯化。方法:根据酮古龙酸菌Y25基因组序列设计引物,通过PCR扩增CcoⅡ基因,酶切后连接pGEX-KG表达载体,转化至大肠杆菌获得重组菌,经IPTG诱导表达融合蛋白GST-CcoⅡ,用谷胱甘肽-Sepharose 4B树脂亲和纯化融合蛋白,并利用Western印迹及质谱对表达蛋白进行鉴定。结果:扩增得到867 bp的CcoⅡ基因,构建了pGEX-KG-CcoⅡ融合表达载体,重组菌经0.4 mmol/L IPTG于20℃诱导16 h,SDS-PAGE分析显示有可溶性表达条带,相对分子质量约为59×103;Western印迹及质谱分析表明,利用亲和层析方法纯化到了目的蛋白。结论:表达并纯化了GST-CcoⅡ融合蛋白,为酮古龙酸菌电子传递链的研究奠定了基础。  相似文献   

18.
A protein purification procedure was developed to efficiently and effectively purify the target enzyme, chitinase A1 of Bacillus circulans WL-12, from Escherichia coli DH5alpha carrying the chiA gene with its natural promoter in the plasmid pNTU110. Chitinase A1 was purified to apparent homogeneity from E. coli periplasm with a final recovery of 90.6%. Two main steps were included in this protein purification procedure, ammonium sulfate precipitation (40% saturation) and anion-exchange chromatography at pH 6.0 using Q Ceramic HyperD column. The yield of chitinase A1 was estimated at 95 microg/L. A polyclonal antibody against chitinase A1 was raised by immunizing BALB/c mice with chitinase A1 purified from E. coli DH5alpha(pNTU110). As indicated by Western blot analysis, a 3000-fold diluted antibody detected purified chitinase A1 from E. coli DH5alpha(pNTU110) in an amount of at least 1 ng and specifically detected chitinase A1 produced by B. circulans WL-12.  相似文献   

19.
Monoacylglycerol lipase [MGLP, EC 3.1.1.23] is produced intracellularly by the moderately thermophilic Bacillus sp. strain H-257. The gene encoding MGLP was cloned, sequenced, and expressed in Escherichia coli. A genomic library of Bacillus sp. strain H-257, prepared in the plasmid vector pACYC184, was screened with a 0.2-kbp DNA fragment amplified by the polymerase chain reaction (PCR) with oligonucleotide primers designed based on the amino acid sequence of a purified MGLP. The plasmid pMGLP31, identified by hybridization with the amplified DNA fragment, contained a 5.3-kbp insert from Bacillus sp. strain H-257 DNA. Sequence analysis of the MGLP gene revealed an open reading frame encoding MGLP consisting of 250 amino acids, with a calculated molecular mass of 27.4 kDa. The deduced amino acid sequence of MGLP contained the consensus pentapeptide (-Gly-Xaa-Ser-Xaa-Gly-), which is conserved among lipases, esterases, and serine proteases. The MGLP is homologous to a putative esterase/lipase from Streptomyces coelicolor (41.8% homology). When pMGLP31 was introduced into E. coli DH1, the transformants produced MGLP intracellularly as an active form to an approximately 13.8-fold greater extent than Bacillus sp. strain H-257. The purified recombinant MGLP was shown to be identical to the native enzyme in terms of chromatographic behavior, isoelectric point, and physicochemical and catalytic properties.  相似文献   

20.
经RTPCR从人新鲜扁桃体组织中扩增人高迁移率族蛋白B1(HMGB1)中的Bbox(88~162残基)的cDNA,构建于载体pUC19,经测序后与GenBank中报道的已知序列完全一致,再构建于原核表达载体pQE80LDHFR中,表达并鉴定目的蛋白.经Ni2+亲和层析柱、多粘菌素B层析柱纯化获得高纯度的DHFRHMGB1Bbox蛋白,然后将此重组HMGB1Bbox加入到人外周血单核细胞(PBMCs)中,37℃,5%CO2下,刺激PBMCs6h,用ELISA检测PBMCs释放TNFα、IL6的量,经检测后证明纯化后的重组HMGB1Bbox能显著地刺激PBMCs释放致炎因子TNFα、IL6.HMGB1Bbox的表达及其生物活性的初步研究,为进一步研究HMGB1Bbox的作用机制以及新型抗炎制剂的研发奠定基础.  相似文献   

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