pET15b-GFP-HCTP、pETl5b-Apoptin-HCTP原核表达载体的构建、表达及其意义

目的：HCTP（HPV tansformed cervical cancer cell targeting penetratin HCTP）是新近发现的一种能特异性识别并穿透HPV转化宫颈癌细胞胞膜的短肽。构建HCTP与绿色荧光蛋白（GFP）、凋亡素（Apoptin）的重组表达载体，原核系统表达并纯化出GFP-HCTP、Apoptin-HCTP融合蛋白，研究HCTP的特异性靶向穿膜效应。方法：根据美国NIH基因库收藏的Apoptin基因序列，利用多重PCR技术拼接出Apoptin cDNA、运用PCR方法以pEGFP-C1质粒为模版扩增获得GFP cDNA片段，将Apoptin及GFP cDNA分别与退火形成的HCTP双链连接并克隆至原核表达载体pETl5b，成功构建pETl5b-GFP-HCTP、pETl5b-Apoptin-HCTP重组表达载体。DNA测序证实重组构建无误，用上述两个重组表达载体转化大肠杆菌BL21（DE3）．以IPTG诱导融合蛋白表达并用Ni-NTA His-Bind Resin蛋白纯化试剂纯化，获得可溶性基因重组融合蛋白GFP-HCTP和Apoptin-HCTP。运用SDS-PAGE及Western blot分析鉴定目的蛋白。结果：成功构建pETl5b-GFP-HCTP、pETl5b-Apoptin-HCTP原核表达载体，经表达、纯化制备了GFP-HCTP和Apoptin-HCTP基因重组融合蛋白。结论：我们使用基因工程技术，经原核表达系统表达制备的GFP-HCTP和Apoptin-HCTP融合蛋白将为进一步研究HCTP的特异穿膜效应以及探讨HCTP作为宫颈癌治疗药物的靶向运送载体提供实验基础。     

胆管癌相关FXYD6基因功能区在大肠埃希菌表达的初步研究

目的对胆管癌相关基因FXYD6基因的功能区进行克隆和表达,以便进一步展开该基因功能研究。方法借助生物信息学方法分析FXYD6基因,设计FXYD6基因信号肽剪切后功能区蛋白体外表达序列,并将其克隆到pBV220表达载体上,继而以大肠埃希菌为表达系统,使功能区蛋白（不含信号肽）获得体外表达。结果该基因主要功能位点位于18～95 aa。PCR扩增出剪切掉信号肽序列的功能区序列（即包含18～95 aa的肽链段）,并成功构建pBV220/FXYD6-ex基因功能区重组表达质粒克隆,其在大肠埃希菌DH5α中表达量最高,表达产物主要以包涵体形式存在。结论获得胆管癌相关FXYD6基因融合蛋白表达产物,为后续研究打下基础。     

Chinese 1基因型弓形虫棒状体蛋白 ROP16的基因克隆表达及生物信息学分析

目的：构建弓形虫Chinese 1基因型TgCtWh3（以后均简称Wh3）株棒状体蛋白（ rhoptry protein ,ROPs）16的原核和真核重组表达质粒及其3D结构。方法参照ROP16序列分别设计引物,采用PCR从弓形虫Chinese 1基因型Wh3株基因组DNA中扩增出编码ROP16的基因片段,克隆至pMD18-T载体;经PCR及测序分析鉴定;阳性克隆的质粒分别亚克隆至原核表达载体pET-28a和真核表达载体pEGFP-C2,分别转化大肠杆菌BL21和DH5α,PCR和酶切鉴定转化菌落插入的序列;将构建的原核表达菌株经IPTG诱导,SDS-PAGE和免疫印迹分析融合蛋白的表达;将构建的真核重组质粒经脂质体转染293T细胞,观察其在细胞中表达;采用生物信息学方法分析构建了蛋白的3 D结构。结果各组均PCR扩增出约2．1 kb ROP16基因的特异片段,序列检测结果均正确;分别亚克隆到原核表达载体pET-28a和真核表达载体pEGFP-C2中,成功构建了Chinese 1基因型弓形虫棒状体蛋白ROP16的原核表达质粒和真核表达质粒;原核表达质粒在大肠杆菌中表达了ROP16的融合蛋白;真核表达质粒在293T细胞中成功表达,成功构建出ROP16基因的3D结构图。结论以pET-28a和pEGFP-C2为载体,分别成功构建并表达了ROP16的原核和真核重组质粒,并构建出其3D结构图。     

抗HBsAg单链抗体与白细胞介素-2融合蛋白的构建与序列测定

目的:构建以人抗乙肝表面抗原（HBsAg）单链抗体（ScFv）为导向作用,白细胞介素-2（IL-2）为治疗作用的融合蛋白原核表达载体pQE 40/ScFv-IL-2。方法:应用PCR技术将抗HBsAg单链抗体与白细胞介素-2在分子水平上进行基因重组,构建中间载体pGEM7Zf（+）/ScFv-IL-2,经酶切鉴定及序列测定正确后,将目的基因片段克隆到pQE 40表达载体中,转化大肠杆菌,经IPTG诱导表达。结果:SDS-PAGE结果显示在相对分子质量约4.3×104Da处,可见蛋白表达带。以鼠抗人IL-2单克隆抗体经免疫印迹验证,该表达蛋白为所设计的融合蛋白。结论:融合蛋白ScFv-IL-2的成功构建及表达,为融合蛋白的纯化和研究开发新型的乙肝导向治疗的基因工程药物打下良好的基础。     

胃泌素释放肽前体融合蛋白的制备及其在肿瘤研究中的应用

目的克隆胃泌素释放肽前体(pro-GRP)基因、构建重组质粒pGEM-T-pro-GRP和表达载体PMS-31b-pro-GRP、在大肠杆菌中热诱导表达并制备融合蛋白。方法从BGC823胃癌细胞中提取总RNA,利用pro-GRP特异引物,扩增人pro-GRP分子的cDNA全长。将pro-GRP基因定向克隆于pGEM-T载体转化JM109,DNA测序鉴定基因序列。将pro-GRP基因定向克隆于原核高效表达载体PMS-31b,转化大肠杆菌POP2136经42℃热诱导表达MS2-pro-GRP融合蛋白。将融合蛋白分离纯化后,十二烷基硫酸钠聚丙烯酰胺凝胶电泳(SDS-PAGE)凝胶鉴定。结果经聚合酶链反应(PCR)扩增成功获得210bp的pro-GRP基因,目的基因序列正确。SDS-PAGE显示热诱导后表达的融合蛋白分子量约为18000。结论成功克隆pro-GRP基因,并表达和纯化了PMS-31b-pro-GRP融合蛋白,为建立pro-GRP检测方法奠定了基础。     

重组 GST-β-GT 融合蛋白的原核表达、纯化及活性鉴定

目的：构建噬菌体β‐GT蛋白的原核重组体系,诱导表达、纯化GST‐β‐GT 融合蛋白并对其进行酶活性测定。方法利用PCR技术从T4噬菌体中扩增β‐GT基因;经T‐A克隆,获得β‐GT基因片段,经酶切连接,构建原核表达载体pGEX‐6P‐1‐β‐GT ;经测序鉴定序列正确后,将所构建的载体转化进入大肠埃希菌BL21（DE3）中进行表达。利用IPTG诱导,经10％ SDS‐PAGE鉴定目的蛋白表达后,采用GST柱纯化目的蛋白;通过酶切和qPCR鉴定其活性。结果成功扩增了噬菌体β‐GT基因;重组质粒在大肠埃希菌BL21（DE3）中诱导表达出GST‐β‐GT融合蛋白;通过GST柱纯化后获得了GST‐β‐GT融合蛋白,纯度达95％;通过酶切和qPCR验证,此GST‐β‐GT融合蛋白具有T4‐β‐GT酶的活性。结论。原核表达GST‐β‐GT融合蛋白具有糖基转移酶活性。     

丙肝病毒非结构4区和5区抗原的克隆表达及纯化鉴定

通过分析丙肝病毒（ＨＣＶ）的非结构４区（ＮＳ４）和５区（ＮＳ５）蛋白的氨基酸序列，推测确定抗原决定簇位点。用ＲＴ－ＰＣＲ技术从中国丙肝病人血甭中扩增克隆含抗原决定簇基因的ＮＳ４及ＮＳ５基因，将该丙段基因分别克隆至质粒表达载体ｐＥＴ２８ａ（＋）内，转化大肠杆菌ＢＬ２１（ＤＥ３），成功了高儿表达ＮＳ４和ＮＳ５蛋白的工程菌，ＩＰＴＧ诱导后两蛋白在工程菌内的表达量分别约占菌体蛋白的３３％和２８％。经Ｓｅｐ     

TOPO克隆构建SARS-CoV M蛋白基因裂殖酵母表达载体及其稳定性

目的 利用TOPO克隆法构建SARS-CoV M蛋白基因的裂殖酵母重组表达载体，并验证重组载体在宿主细胞中的稳定性。方法 运用逆转录-聚合酶链反应（RT-PCR）技术从SARS-CoV RNA中扩增出M蛋白基因,AT克隆构建出序列正确的pMD18-T-M重组载体。设计含Kozak序列的引物从pMD18-T-M载体上亚克隆出M蛋白基因，与裂殖酵母表达载体pNMT1-TOPO进行TOPO克隆,构建出重组表达载体pNMT1-M,转化TOP10感受态细胞，菌落PCR鉴定阳性转化子后进行测序鉴定。将序列正确的pNMT1-M重组载体电转化入裂殖酵母TCP1菌株中,在EMM培养基中诱导表达,连续传代100代，在EMM+T培养基中验证其稳定性。结果 RT-PCR获得666 bp的片段,pMD18-T-M重组载体经测序验证序列正确；重组表达载体pNMT1-M经菌落PCR和测序鉴定均正确;重组裂殖酵母菌经诱导后，SDS-PAGE检测出了表达条带;重组表达载体连续传代后,未发现丢失现象。结论 成功地构建出了SARS-CoV M蛋白基因的裂殖酵母表达载体，验证了其在裂殖酵母中能稳定地进行遗传,为下一步的表达优化、活性和功能研究垫定了基础.     

TT病毒结构蛋白抗原在大肠杆菌中的表达及应用

目的 用原核系统表达TT病毒（TTV）的重组蛋白抗原，建立诊断（TTV）感染的特异性方法。方法 采用PCR方法扩增TTVORF2基因，将之插入到测序质粒载体中进行测序，验证序列正确后将之嵌入到原核表达载体pQE30中，并转化大肠杆菌M15菌株，进行诱导表达。用SDS－PAGE分析表达产物。表达产物经Ni-NTA柱层析纯化后，得到纯度为90％的ORF蛋白抗原。用TTV感染者的阳性血清对该蛋白进行了Western-Blot分析，用间接ELISA方法检测血清抗－（TTV）IgG抗体。结果 经IPTG诱导后，筛选出2株高表达株。结论 该蛋白具有良好的抗原活性，可以有效地用于TTV的感染检测中。     

IL-13融合蛋白表达载体与非融合蛋白表达载体的构建与比较

采用RT－PCR技术直接从激活的健康人外周血单个核细胞中扩增得到hIL－13的基因片段，通过DNA重组技术分别将其插入到含有PRPL启动子的高效表达载体pBV220及含tac启动子、lac1阻遏蛋白基因及凝血酶识别位点的融合蛋白表达载体pGEX－4T－2中，成功地构建了hIL－13的原核非融含蛋白表达菌株hIL－13－PBV220／DHS5a及融合蛋白表达菌株hIL－13－PGEX－4T－2／TG1，分别经42℃热诱导及异丙基硫代半乳糖苷（IPTG）化学诱导后，SDS－PAGE结果表明IL－13仅以GST融合蛋白的形式在E.coli中获得了表达，表达量约占菌体蛋白总量的10％～30％。IL-13的蛋白单体在原核细胞中表达量很低。     

Formulating protein therapeutics into particulate forms

This review is aimed at providing critical comments on selected approaches to formulating protein drugs into particulate forms feasible as practical pharmaceutical dosage forms. From a practical point of view, the need to formulate protein therapeutics into particulate forms includes inhalation and sustained-release delivery proteins, stabilizing and incorporating proteins into tissue engineering scaffolds and medical devices, as well as protecting and targeting protein therapeutics in an in vivo environment. For either of the applications, a common challenge is that proteins are easily denatured during particle-forming processes in which water–oil or water–air interfaces, multivalent ions or polyelectrolytes, strong shear stress and/or reactive crosslinking agents are often involved. Moreover, methods to protect proteins during the particle-forming processes must not compromise their pharmaceutical objectives, such as encapsulation efficiency, burst-free controlled release and storage convenience. Although numerous methods have been reported to formulate proteins into particulate systems, few of them meet the criteria above. To stimulate critical and interactive readings of the vast and booming information, the authors also provide their analysis regarding the feasibility of the formulation strategies summarized in this review.     

Inhibitors of protein farnesylation 1998

Protein farnesyltransferase (PFTase) inhibitors are being studied as mechanistically novel antitumour agents. Whilst the antiproliferative effects of PFTase inhibitors are well-documented in cell culture and rodent animal models, clinical studies which began in 1997 should soon reveal their utility in human cancer patients. This review summarises the scientific and patent literature covering PFTase inhibition that has been published since the previous two updates [1,2]. New biology with a potential impact on the utility of PFTase inhibitors is reviewed first, followed by a discussion of new PFTase inhibitors. As in earlier updates, compounds are grouped according to their kinetic mechanism of PFTase inhibition.     

儿童非霍奇金淋巴瘤EB病毒LMP-1和P53、bcl-2表达的关系

目的探讨儿童NHL EB病毒LMP-1和P53、bcl-2蛋白的表达及关系.方法采用免疫组化Envision法检测64例儿童NHL中LMP-1和P53、bcl-2蛋白.结果 (1)P53蛋白阳性表达39例(60.9%),表达强度与淋巴瘤恶性程度呈正相关;阳性表达率在低恶组与中、高恶性组间有显著性意义,P＜0.01.bcl-2蛋白阳性表达37例(53.8%),bcl高于TCL,低恶性高于高恶性.(2)LMP-1蛋白阳性表达45例(70.3%),阳性表达率与肿瘤恶性程度和年龄有统计学意义,P＜0.01;而与淋巴瘤免疫表型、性别和发病部位无关.LMP-1表达与P53及bcl-2的表达呈正相关.结论 EBV感染是儿童NHL发生发展不可忽视的病毒致病因素,其致病作用可能是通过上调P53、bcl-2蛋白实现的.     

Biological functions and structural biology of Plasmodium falciparum autophagy-related proteins: The under-explored options for novel antimalarial drug design

Malaria remains a threat to global public health and the available antimalarial drugs are undermined by side effects and parasite resistance, suggesting an emphasis on new potential targets. Among the novel targets, Plasmodium falciparum autophagy-related proteins (PfAtg) remain a priority. In this paper, we reviewed the existing knowledge on the functions and structural biology of PfAtg including the compounds with inhibitory activity toward P. falciparum Atg8-Atg3 protein–protein interaction (PfAtg8-PfAtg3 PPI). A total of five PfAtg (PfAtg5, PfAtg8, PfAtg12, PfAtg18, and Rab7) were observed to have autophagic and/or non-autophagic roles. Available data showed that PfAtg8 has conserved hydrophobic pockets, which allows it to interact with PfAtg3 to form PfAtg8-PfAtg3 PPI. Additionally, 2-bromo-N-(4-pyridin-2-yl-1,3-thiazol-2-yl) benzamide was identified as the most powerful inhibitor of PfAtg8-PfAtg3 PPI. Due to the dearth of knowledge in this field, we hope that the article would open an avenue to further research on the remaining PfAtg as possible drug candidates.     

Computational re-design of protein structures to improve solubility

ABSTRACT

Introduction: The rapid development of protein therapeutics is providing life-saving therapies for a wide range of human diseases. However, degradation reactions limit the quality and performance of these protein-based drugs. Among them, protein aggregation is the most common and one of the most challenging to prevent. Aggregation impacts biopharmaceutical development at every stage, from discovery to production and storage. In addition, regulators are highly concerned about the impact of protein aggregates on drug product safety.

Area covered: Herein, the authors review existing protein aggregation prediction approaches, with a special focus on four recently developed algorithms aimed to predict and improve solubility using three-dimensional protein coordinates: SAP, CamSol, Solubis and Aggrescan3D. Furthermore, they illustrate their potential to assist the design of solubility-improved proteins with a number of examples.

Expert opinion: Aggregation of protein-based drugs is, traditionally, addressed via wet lab experiments, using trial and error approaches that are expensive, difficult to perform and time-consuming. The structure-based in silico methods we describe here can predict accurately aggregation propensities, allowing researchers to work with pre-selected, well-behaved, protein candidates. These methods should contribute to the reduction of the time to the marketplace along with industrial costs and improve the safety of future therapeutic proteins.     

Stability of the Thrombolytic Protein Fibrolase: Effect of Temperature and pH on Activity and Conformation

The effect of temperature and pH on the activity and conformation of the thrombolytic protein fibrolase was examined. Fibrolase maintained proteolytic activity over 10 days at room temperature (22°C). At 37°C, greater than 50% of the proteolytic activity was lost within 2 days and no activity remained after 10 days. Circular dichroism (CD) spectra at elevated temperatures showed that alphahelical structure was lost in a cooperative transition (T _m of 50°C at pH 8). Structural changes were detected by NMR prior to unfolding which were not observable by CD, and the T _m determined by NMR was 46°C at pD 8. The effect of pH on the proteolytic activity and structure of fibrolase was examined over the pH range from 1 to 10. Activity was maintained at neutral to alkaline pH values from pH 6.5 to pH 10.0 but decreased substantially in acidic media. While CD spectra indicated little variation in secondary structure over the pH range 5 to 9, significant differences were noted at pH 2 to 3. The melting temperature of fibrolase decreased to 43°C at pH 5. Protein concentrations determined over the pH range 1 to 10 showed an apparent solubility minimum at pH 5.0, which did not correspond to the isoelectric point of 6.5. Explanations for these observations are proposed.     

Prediction of colloidal stability of high concentration protein formulations

Abstract

A major aspect determining the colloidal properties of proteins in solution is the interaction between them and with surrounding molecules. These interactions can be described by the concentration dependency of the protein diffusivity (k_D), as derived by dynamic light scattering and was determined for different solutions of monoclonal antibodies varying in pH, ionic strength and presence/absence of co-solute(s). Concerning colloidal stability, protein solutions of different k_D values are evaluated, based on their initial solution opalescence, to assess protein association. The current investigation shows that solution conditions with large k_D values, indicating high repulsive protein–protein interactions, show lower initial opalescence, compared to solution conditions with low k_D values. Upon applying stirring stress, to assess colloidal stability, the trend is such that, the higher k_D values are, the more stable the protein solutions are, as long as the thermodynamic and conformational stability is not impaired. Besides, k_D allows ranking of solution conditions for highly concentrated immunoglobulin solutions up to concentrations of ～200?mg?mL^?1 with regard to protein self-association and thus opalescent properties. The present study shows that the protein interaction parameter k_D can be used as a surrogate parameter for a qualitative prediction of protein association and, thus, colloidal protein stability.     

Docking and scoring: applications to drug discovery in the interactomics era

Background: Computational approaches such as docking and scoring are becoming routine in drug discovery as a complement to other more traditional techniques. However, so far, computer drug design methods have been applied to inhibit the function of individual proteins, and there is little available data on the use of these computational techniques to target protein–protein interactions. Objective: To establish a strategy for the use of current computational tools in drug discovery targeting protein–protein interactions. Method: Individual techniques applied to specific cases could be studied to derive a general strategy for targeting protein–protein interactions. Conclusion: Protein docking, interface prediction and hot-spot identification can contribute to the discovery of small molecule inhibitors targeting protein interactions of therapeutic interest, especially when little structural information is available.     

Influence of retinoic acid on TBX1 expression in myocardial cells induced by Shh and Fgf8

The aim of this study was to explore the regulatory mechanism of retinoic acid (RA) on the TBX1 gene expression in myocardial cells. Ventricular cardiocytes were isolated from neonatal rats and cultured, and then treated with different concentrations of retinoic acid. The expression of Shh and Fgf8 at mRNA and protein levels in neonatal rat myocardial cells were measured by using RT-PCR and Western blot technique, respectively. There was basal expression of Shh and Fgf8 in the control group. When treated with 3 × 10⁻⁷ mol/L RA, we observed that the expression of Shh mRNA and protein in neonatal rat myocardial cells were up-regulated by 1.51 (P < 0.05) and 1.10 times (P < 0.05), respectively. In comparison with the control group, under the concentration of 5 × 10⁻⁷ mol/L RA, they were up-regulated by 2.21 (P < 0.05) and 2.38 times (P < 0.05) individually. Meanwhile, we could detect that the expression of Fgf8 mRNA and protein were up-regulated by 2.50 times (P < 0.05) and 80% (P < 0.05) separately compared with the control group after stimulation of 3 × 10⁻⁷ mol/L RA, and they were up-regulated by 3.48 (P < 0.05) and 2.04 times (P < 0.05) individually after stimulation of 5 × 10⁻⁷ mol/L RA. The results indicated that RA could induce the expression of Shh and Fgf8 in neonatal rat myocardial cells. At the same time, it has shown that Shh and Fgf8 were involved in the regulation process of RA on TBX1 expression.     

GPCR-Gα融合蛋白及其在oGPCRs配基筛选中的应用

GPCRGα融合蛋白是近几年用于受体研究的新颖手段之一,它的表达确保了受体与G蛋白之间1∶1的化学计量关系、空间位置上的邻近性及适宜于高通量的配基筛选,使其为孤儿G蛋白偶联受体提供了一种新的研究策略,将在孤儿受体的配基筛选中发挥重要作用,对研发以oGPCR为作用靶点的新药产生积极意义。