白细胞介素对大鼠海马培养神经元膜电特性的影响

用细胞内微电极记录方法研究了重组人白细胞介素－１β（ｒｈＩＬ－１β）和重组人白细胞介素－２（ｒｈｉＬ－２）对分散培养的新生大鼠海马神经元膜电性质的影响。采用压力脉冲微量给药技术将白介素施加于所记录的细胞表面。结果发现：１００Ｕ／ｍｌ浓度的ｒｈＩＬ－１β使受作用的海马神经元超极化４．２０±１．８６ｍＶ;１００Ｕ／ｍｌ浓度的ｒｈＩＬ－２使５０％受作用的海马神经元去极化１１．１２±３．７１ｍＶ,并伴有强烈的自发放电反应,而１０００Ｕ／ｍｌ浓度的ｒｈＩＬ－２使１００％受作用的神经元超极化３．２５±０．６３ｍＶ,这些神经元的膜阻抗均无明显变化。本实验结果提示ｒｈＩＬ－１β和ｒｈＩＬ－２可显著影响体外培养海马神经元的膜兴奋性。     

重组人白细胞介素-6的纯化

重组人白细胞介素－６（ｒｈＩＬ－６）在工程菌ｐＢＶ２２０／ｒｈＩＬ－６／ＤＨ５ａ中以包涵体形式高效表达。ｒｈＩＬ－６经过工程菌体破碎、包涵体分离及抽提、复性、色谱分离后得到高度纯化。纯化产物纯度９５％,具有良好的生物学活性     

反相高压液相色谱折叠重组人白细胞介素-2

重组人白细胞介素－２（ｒｈＩＬ－２）基因表达产物在大肠杆菌中以不溶性包涵体形式存在,经过菌体发酵和收集、超声破菌、包涵体抽提、稀释透析初步复性、反相高压液相色谱纯化,终产物纯度大于９９％。反相高压液相色谱不仅可以纯化ｒｈＩＬ－２,且使产物的总活性提高７．９－９倍,比活性提高１４￣１８倍,达到１．５×１０＾７ｕ／ｍｇ蛋白质,蛋白得率为５０％￣５６％。结果表明,反相高压液相色谱具有纯化和显提高ｒｈＨ     

大肠杆菌表达重组人白细胞介素-9的纯化及部分性质

表达重组人白细胞介素－９（ｒｅｃｏｍｂｉｎａｎｔｈｕｍａｎｉｎｔｅｒｌｅｕｋｉｎ－９ｒｈＩＬ－９）的大肠杆菌经破碎、包涵体洗涤、裂解提取、凝胶过滤和离子交换色谱分离,得到了电泳纯的ｒｈＩＬ－９,回收率６６％,分子量与理论值相符,有刺激小鼠骨髓巨核系集落生成的活性．为ｒｈＩＬ－９的大规模制备及更深入的研究奠定了基础     

反相高压液相色谱折叠重组人白细胞介素-2

重组人白细胞介素２（ｒｈＩＬ２）基因表达产物在大肠杆菌中以不溶性包涵体形式存在,经过菌体发酵和收集、超声破菌、包涵体抽提、稀释透析初步复性、反相高压液相色谱纯化,终产物纯度大于９９％。反相高压液相色谱不仅可以纯化ｒｈＩＬ２,且使产物的总活性提高７９～９倍,比活性提高１４～１８倍,达到１５×１０７ｕ／ｍｇ蛋白质,蛋白得率为５０％～５６％。结果表明,反相高压液相色谱具有纯化和显著提高ｒｈＩＬ２折叠效率的双重功效,为非ＳＤＳ变复性法生产ｒｈＩＬ２提供了简便有效的方法     

人白细胞介素11的基因克隆及其在大肠杆菌中的表达

从人胚肺二倍体细胞ＫＭＢ１７抽提总ＲＮＡ,经ＲＴ－ＰＣＲ扩增到人ＩＬ－１１ｃＤＮＡ,克隆于ｐＢＳ－ＳＫ,以双脱氧链终止法进行序列分析;扩增去除Ｎ 端第一个氨基酸的ＩＬ－１１ｃＤＮＡ,克隆于硫氧还蛋白融合表达载体ｐＴｈｉｏＨｉｓＡ,经过对表达质粒的改造,使融合表达的ＩＬ－１１能被肠激酶精确切割;表达产物经金属鏊合亲合层析后经肠激酶切,再通过阳离子交换层析纯化后,用其依赖细胞株７ＴＤ１检测活性．结果表明,克隆的ＩＬ－１１ｃＤＮＡ 序列与文献报道一致;表达的融合蛋白占菌体总蛋白的３０％ 左右,以可溶性形式存在;纯化产物具有维持依赖细胞株生长的能力．由此,获得了较高纯度的具有生物学活性的ｒｈＩＬ－１１,为中试生产奠定了基础．     

体外培养大鼠海马细胞白细胞介素－1的表达及缺氧的影响

采用免疫组化方法,观察了体外培养大鼠海马细胞对人重组白细胞介素１β（ｒｈＩＬ－１β）抗血清的免疫反应以及缺氧的影响。结果可见,体外培养的大鼠海马神经元和神经胶质细胞对抗ｒｈＩＬ－１β抗血清均呈弱阳性免疫染色反应,缺氧后免疫染色反应明显增强。经图像分析表明,缺氧后神经元和神经胶质细胞的平均光密度均较缺氧前增加,尤以缺氧２ｈ时增加最明显,继续缺氧４─１２ｈ,神经元和神经胶质细胞的平均光密度又逐渐减弱。以上结果表明,大鼠海马脑区存在抗ｒｈＩＬ－１β抗血清的免疫反应细胞;缺氧使对抗ｒｈＩＬ－１β抗血清的免疫染色反应增强,提示ＩＬ－１β与脑缺氧损伤的调控有关。     

嗜热毛壳菌内切β-葡聚糖酶的分离纯化及特性

探讨了液体发酵嗜热毛壳菌（Chaetomium thermophile)产生的内切β－葡聚糖酶的分离纯化及特性。粗酶液经硫酸铵分级沉淀,DEAE－Seplharose Fast Flow阴离子层析,Pheny1-Sepha-rose疏水层析,Sephacry1 S-100分子筛层析等步骤便可获得凝胶电泳均一的内切β－葡聚糖酶,经12．5％SDS－PAGE和凝胶过滤层析法分离纯化酶蛋白的分子量约为67．8kD的69．8kD。该酶反应的最适温度和pH分别为60℃和4．0－4．5在pH5.0条件下,该酶在60℃下稳定：70℃保温1h后,仍保留30％的活性;在80摄氏度的半衰期为25min,金属离子内切β－葡聚糖酶的活性影响较大,其中Na^ 对酶有激活作用;Fe^2 ,Ag^ ,Cu^2 ,Ba^2 ,Zn^2 等对酶有抑制作用。该酶对结晶纤维素有没水解能力。     

圆弧青霉碱性脂肪酶的分离纯化的特性

圆弧青霉突变株ＰＧ３７发酵液经离心、硫酸铵盐析、疏水层析、阴离子交换层析和凝胶过滤分离纯化得到了比活性为每毫克蛋白质５２００ｕ的碱性脂肪酶,纯化倍数１６．５,得率３３．２％,在聚丙烯酰胺凝胶电泳（ＰＡＧＥ）和ＳＤＳ－聚丙烯酰胺凝胶电脉（ＳＤＳ－ＰＡＧＥ）上均呈现单一 白质条带。ＳＤＳ－ＰＡＧＥ和凝胶过滤分别测得酶的分子量为２７．５ｋＤ和２９．ｋＤ,表明该酶以单体形式存在。Ｎ末端１０个氨基酸的序列测     

低氧预处理对大鼠海巴神经元缺氧耐受性和IL—1β表达 …

目的：观察低氧预处理对大鼠海巴神经元缺氧耐受性和白细胞介素－１β（ＩＬ－１β）表达的影响。方法：取培养１２ｄ的两组（对照组和低氧预处理组）培养神经元,同时置于缺氧环境（０．９Ｌ／ＬＮ２,０．１Ｌ／ＬＣＯ２）中培养２、４、８和１２ｈ。分别观察它们的形态变化和神经元存活数,并用抗ｒｈＩＬ－１β单克隆抗体进行免疫组织化学染色,观察缺氧对大鼠海马培养神经元ＩＬ－１β表达的影响。结果：经低氧预处理的海马神经     

大肠杆菌表达的人重组IL-3的纯化

本文继大肠杆菌表达含凝血酶切点的人重组IL-3融合蛋白成功的基础上进一步探讨了天然型rhIL-3的纯化。超声破碎细菌细胞得包涵体,经洗涤处理可使包涵体纯度达90％,用8mol/L尿素变性溶解包涵体沉淀后直接稀释复性,再超滤浓缩、凝血酶消化,释放天然型rhIL-3。经DEAE Sepharose Fast Flow和Sepharcyl-100 HR层析得到天然型IL-3,纯度达96％,回收率20％以上,具有刺激正常人骨髓细胞形成集落的活性。本实验为大批量重组IL-3的生产创造了条件。     

重组人IL-4大肠杆菌表达与纯化

根据大肠杆菌密码子偏爱性优化并合成人白细胞介素4基因,以pET30a( )为载体构建了重组表达质粒pET30a( )/rhIL-4,将重组质粒转化大肠杆菌BL21(DE3)感受态细胞,诱导表达并超声破菌检测重组蛋白的表达形式。采用5L发酵罐培养工程菌,发酵液OD600为0.6时诱导3.5h收集菌体,检测目的蛋白的表达量。收集的菌体经压榨破菌获得包涵体,通过包涵体变性、层析、透析复性等方法对rhIL-4进行纯化。采用人红细胞白血病细胞(TF-1)测定纯化的rhIL-4的生物活性。测序表明目的基因已插入载体pET30a( )中,重组蛋白以包涵体形式表达,单位体积重组蛋白的表达量达200mg/L发酵液,建立了对包涵体形式表达的rhIL-4纯化方法,最终得率为40mg/L发酵液,纯度大于98%,回收率为20%以上。免疫印迹法检测诱导表达的重组蛋白和纯化的蛋白为IL-4,N端氨基酸序列测定结果与理论相符,生物活性检测纯化的蛋白比活性达2.5×106AU/mg。这为rhIL-4进一步产业化研究建立了基础。     

Production and purification of refolded recombinant human IL-7 from inclusion bodies

A recombinant form of human rhIL-7 was overexpressed in Escherichia coli HMS174 (DE3) pLysS under the control of a T7 promoter. The resulting insoluble inclusion bodies were separated from cellular debris by cross-flow filtration and solubilized by homogenization with 6 M guanidine HCl. Attempts at refolding rhIL-7 from solubilized inclusion bodies without prior purification of monomeric, denatured rhIL-7 were not successful. Denatured, monomeric rhIL-7 was therefore initially purified by size-exclusion chromatography using Prep-Grade Pharmacia Superdex 200. Correctly folded rhIL-7 monomer was generated by statically refolding the denatured protein at a final protein concentration of 80-100 microg/ml in 100 mM Tris, 2mM EDTA, 500 mM L-arginine, pH 9.0, buffer with 0.55 g/l oxidized glutathione at 2-8 degrees C for at least 48 h. The refolded rhIL-7 was subsequently purified by low-pressure liquid chromatography, using a combination of hydrophobic interaction, cation-exchange, and size-exclusion chromatography. The purified final product was >95% pure by SDS-PAGE stained with Coomassie brilliant blue, high-pressure size-exclusion chromatography (SEC-HPLC), and reverse-phase HPLC. The endotoxin level was <0.05 EU/mg. The final purified product was biologically active in a validated IL-7 dependent pre-B-cell bioassay. In anticipation of human clinical trials, this material is currently being evaluated for safety and efficacy in non-human primate toxicology studies.     

One-step purification of Taq DNA polymerase using nucleotide-mimetic affinity chromatography

The thermostable Thermus aquaticus DNA polymerase (Taq Pol) has been the key factor in transforming the initial PCR method into one with huge impact in molecular biology and biotechnology. Therefore, the development of effective affinity adsorbents for the purification of Taq Pol, as well as other DNA polymerases, attracts the attention of the enzyme manufacturers and the research laboratories. In this report we describe a simple protocol for the purification of Taq Pol from E. coli lysates, leading to enzymes of high specific activity and purity. The protocol is based on a single affinity chromatography step, featuring an immobilized ligand selected from a structure-biased combinatorial library of dNTP-mimetic synthetic ligands. The ligand library was screened for its ability to bind and purify Taq Pol from E. coli lysates. One immobilized ligand (mABSGu) of the general formula X-Trz-Y, bearing 9-aminoethylguanine (AEGu) and aniline-2-sulfonic acid (mABS) linked on the triazine scaffold (Trz), displayed the highest purifying ability. Adsorption equilibrium studies with this affinity ligand and Taq Pol determined a dissociation constant (KD) of 0.12 mM for the respective complex, whereas ATP prevented the formation of the mABSGu-Taq Pol complex. The mABSGu affinity adsorbent was exploited in the development of a facile Taq Pol purification protocol, affording homogeneous enzyme (>99% purity, approximately 61 500 U/mg) in a single chromatography step. Quality control tests showed that Taq Pol purified on the mABSGu affinity adsorbent is free of nucleic acids and contaminating nuclease activities.     

A simple method for purification of Shiga or Shiga-like toxin from Shigella dysenteriae and Escherichia coli O157: H7 by immunoaffinity column chromatography

Abstract A simple method was developed for purifying Shiga toxin and Shiga-like toxin from the culture supernatants and cell lysates of Shigella dysenteriae type 1 and Escherichia coli O157 : H7 grown in modified syncase media. Two steps, DEAE cellulose column chromatography and immunoaffinity column chromatography, were sufficient for obtaining purified toxin. By this procedure, about 0.32–0.75 mg of purified toxin was obtained from 5 1 of culture with high recovery rate (53–62%). The toxins purified by this method from the culture supernatants and cell lysates of S. dysenteriae and E. coli O15 : H7 were immunologically, biologically and structurally indistinguishable.     

一种白细胞介素2基因变构体的高效表达与纯化工艺

利用定点诱变技术构建表达质粒pET15b-MhIL-2并将其在大肠杆菌中进行表达发酵的优化研究,高效表达出可溶性的MhIL-2重组蛋白。蛋白经过亲和层析、Thrombin酶切、离子交换层析和凝胶过滤层析纯化,MhIL-2纯度达95%,且MhIL-2比hIL-2具有更强的促进T细胞增殖生物活性。     

Expression, purification, and in vitro refolding of a humanized single-chain Fv antibody against human CTLA4 (CD152)

A human-derived single-chain Fv (scFv) antibody fragment specific against human CTLA4 (CD152) was produced at high level in Escherichia coli. The scFv gene was cloned from a phagemid to the expression vector pQE30 with a N-terminal 6His tag fused in-frame, and expressed as a 29 kDa protein in E. coli as inclusion bodies. The inclusion body of scFv was isolated from E. coli lysate, solubilized in 8M urea with 10mM dithiothreitol, and purified by ion-exchange chromatography. Method for in vitro refolding of the scFv was established. The effects of refolding buffer composition, protein concentration and temperature on the refolding yield were investigated. The protein was renatured finally by dialyzing against 3mM GSH, 1mM GSSG, 150 mM NaCl, 1M urea, and 50 mM Tris-Cl (pH 8.0) for 48 h at 4 degrees C, and then dialyzed against phosphate-buffered saline (pH 7.4) to remove remaining denaturant. This refolding protocol generated up to a 70% yield of soluble protein. Soluble scFv was characterized for its specific antigen-binding activity by indirect cellular ELISA. The refolded scFv was functionally active and was able to bind specifically to CTLA4 (CD152). The epitopes recognized by refolded anti-CTLA4 scFv do not coincide with those epitopes recognized by CD80/CD86.     

Clinical manufacturing of recombinant human interleukin 15. I. Production cell line development and protein expression in E. coli with stop codon optimization

Interleukin 15 (IL-15) has shown remarkable biological properties of promoting NK- and T-cell activation and proliferation, as well as enhancing antitumor immunity of CD8(+) T cells in preclinical models. Here, we report the development of an E. coli cell line to express recombinant human Interleukin-15 (rhIL-15) for clinical manufacturing. Human IL-15 cDNA sequence was inserted into a pET28b plasmid and expressed in several E. coli BL21 strains. Through product quality comparisons among several E. coli strains, including E. coli BL21(DE3), BL21(DE3)pLysS, BLR(DE3)pLysS, and BL21-AI, E. coli BL21-AI was selected for clinical manufacturing. Expression optimization was carried out at shake flask and 20-L fermenter scales, and the product was expressed as inclusion bodies that were solubilized, refolded, and purified to yield active rhIL-15. Stop codons of the expression construct were further investigated after 15-20% of the purified rhIL-15 showed an extraneous peak corresponding to an extra tryptophan residue based on peptide mapping and mass spectrometry analysis. It was determined that the presence of an extra tryptophan was due to a stop codon wobble effect, which could be eliminated by replacing TGA (opal) stop codon with TAA (ochre). As a novel strategy, a simple method of demonstrating lack of tRNA suppressors in the production host cells was developed to validate the cells in this study. The E. coli BL21-AI cells containing the rhIL-15 coding sequence with a triplet stop codon TAATAATGA were banked for further clinical manufacturing.     

Aggregation of ALS mutant superoxide dismutase expressed in Escherichia coli

Although large amounts of wild-type human Cu,Zn superoxide dismutase (SOD) are easily expressed in Escherichia coli, the amyotrophic lateral sclerosis-associated mutants have a strong propensity to aggregate into inclusion bodies. The alanine to valine mutation at the fourth codon (A4V) is responsible for a rapidly progressive disease course and is particularly prone to aggregation when expressed in E. coli. We found that A4V SOD remained soluble when expressed at 18 degrees C, but >95% A4V SOD aggregated in inclusion bodies when expressed at 23 degrees C or above. The SOD aggregates dissolved with 4 M urea, suggesting that intermolecular hydrophobic interactions were predominantly responsible for making SOD insoluble. Many of the urea-solubilized subunits were cross-linked via disulfide bridges. Fully active mutant SOD could be produced by dialyzing urea away in the presence of beta-mercaptoethanol and subsequently adding copper plus zinc, providing a fast procedure for purifying hundreds of milligrams of protein. Extensive rinsing removed most contaminating E. coli proteins from A4V SOD inclusion bodies except for a 37 kDa protein identified as outer membrane protein F using MALDI ToF/ToF mass spectrometry. Our results indicate that metal-deficient ALS-mutant SOD folds into stable apo conformation able to rebind metals. At high protein concentrations, SOD forms aggregates through hydrophobic interactions between subunits that seem to act as a kinetic snare to entrap additional proteins.     

大肠杆菌AE109青霉素G酰化酶的分离纯化及性质研究

 由发酵培养液所得大肠杆菌AE109菌体,先经高渗休克处理,继经D-苯甘氨酸-Sepharose 4B和DEAE-纤维素柱层析分离纯化得到青霉素G酰化酶,酶制品在非变性条件下的聚丙烯酰胺凝胶电泳上呈一条区带,而且可以结晶。在SDS变性条件下解离为α和β两个亚基。 酶性质的研究结果表明,由大肠杆菌工程菌AE109菌株所得青霉素G酰化酶与其亲本大肠杆菌AS1.76菌株所得青霉素G酰化酶性质相同。