糖蛋白的凝胶电泳和电印迹染色鉴定技术

糖基化是蛋白质翻译后修饰最重要的方式之一,是必需的生理过程,对蛋白质生物学功能的正确发挥起着至关重要的作用。二维凝胶电泳(two-dimensional gel electrophoresis,2-DE)是常用的分离蛋白质的方法之一,糖蛋白在凝胶上的检测是分离鉴定糖蛋白的关键之一。本文对近年来凝胶电泳、电印迹技术中鉴定糖蛋白的衍生试剂的研究和应用进行了综述,对多种衍生试剂衍生糖蛋白的机理作了介绍。

PVDF膜在电印迹法中的应用

本文介绍的是聚偏二氟乙烯膜（Polyvinylidenedifluoride，PVDF）在电印迹法中的应用，即将蛋白质SDS聚丙烯酰胺凝胶电沪后的条带电转移到PVDF膜上，随着蛋白质的转移，蛋白质在凝胶上的相对位置将在膜上得到相对的反映，然后将膜上所需蛋白质条带切割下来，直接可以用于N－未端序列分析及总氨基酸组成分析。该方法无需做到蛋白质的完全纯化，所以方法简单快速，所需样品量极少。

北方汉族人群α_1-抗糜蛋白酶表型调查分析

目的 了解中国北方汉族人群α1 抗糜蛋白酶 (α1 antichymotrypsin ,α1 ACT)表型的分布情况 ,探讨地理环境是否影响α1 ACT的表型分布。方法 建立测定α1 ACT的等电聚焦免疫印迹技术 ,并应用此方法对居住在北京市汉族群体的 10 0例个体的α1 ACT蛋白表型进行分析。结果 发现北京市汉族群体α1 ACT具有 3种表型 ,且有一种不同于重庆市汉族群体。结论 地理环境可能影响α1 ACT的表型分布 ,为进一步了解我国南北人群和各民族间α1

Variation of Cyclin B1-like Protein During the Cell Cycle of Physarum polycephalum

Physarum polycephalum L., a naturally synchronized myxomycophyta, was demonstrated to contain a cyclin B1-like protein by Western blot and immunoelectron microscopy. The content and subcellular location of the protein varied during the cell cycle. The cyclin B1-like protein was first detected in the plasmodia of S phase while it did not appear in the nuclei until late G2 phase. The content of the protein in both the plasmodia and nuclei rose gradually onwards, peaked at metaphase and disappeared abruptly at ana-telophase. The protein was found to be distributed in both the cytoplasm and nuclei in late G2 phase and metaphase. In nuclei, the protein was mainly located in the chromosomal and nucleolar areas. The results suggest that the cyclin B1-like protein of P. polycephalum begins to be synthesized at S phase, enters the nuclei at late G2 phase, accumulates in both cytoplasm and nuclei onwards and breaks down at ana-telophase. The results also suggest that the cyclin B1-like protein acts as a cytoplasmic-nuclear protein during certain phases of the cell cycle.

北京地区汉族群体凝血因子B的遗传多态性

应用聚丙烯酰胺等电聚焦(IEF)免疫印迹技术,调查了北京地区汉族群体凝血因子B(FB)的遗传多态性。推算出FB的基因频率为:FB1=0.3552,FB2=0.0174,FB3=0.6236,该遗传标记的表现型频率分布符合Hard-Weinberg平衡定律。

A p34 ^( cdc2) _like Protein Is Localized in Both Nuclei and Cytoplasm of Physarum polycephalum

目前关于动物和酵母细胞中p34cdc2 的定位研究结果尚存在分歧 ,而关于该蛋白在植物细胞中的定位尚不清楚。以多头绒泡菌 (Physarumpolycephalum)S期、G2早期、G2中期、G2晚期、前期、中期和后末期的原质团和细胞核为材料进行免疫印迹 ,发现原质团和细胞核都含有一种分子量约 34kD的类p34cdc2 蛋白 ,该蛋白在原质团和细胞核中的含量在整个细胞周期进程中基本保持稳定。以抗p34cdc2 单克隆抗体为探针的免疫电镜结果显示 ,类p34cdc2 蛋白既分布于细胞核也分布于细胞质中 ,在细胞核中主要与染色体和核仁结合。经抗p34cdc2 单克隆抗体处理后 ,多头绒泡菌的有丝分裂启始迟滞约 2h。结果表明 ,多头绒泡菌类p34cdc2 蛋白存在于细胞核和细胞质中 ,与细胞有丝分裂密切相关 ,其含量在细胞周期进程中基本保持稳定。

Effects of α-mangostin on apoptosis induction of human colon cancer

AIM:To investigate the effect of α-mangostin on the growth and apoptosis induction of human colon cancer cells.METHODS:The three colorectal adenocarcinoma cell lines tested (COLO 205,MIP-101 and SW 620) were treated with α-mangostin to determine the effect on cell proliferation by MTT assay,cell morphology,chromatin condensation,cell cycle analysis,DNA fragmentation,phosphatidylserine exposure and changing of mitochondrial membrane potential.The molecular mechanisms of α-mangostin mediated apoptosis were further investigated by Western blotting analysis including activation of caspase cascade,cytochrome c release,Bax,Bid,p53 and Bcl-2 modifying factor.RESULTS:The highest inhibitory effect of α-mangostin on cell proliferation of COLO 205,MIP-101 and SW 620 were 9.74 ± 0.85 μg/mL,11.35 ± 1.12 μg/mL and 19.6 ± 1.53 μg/mL,respectively.Further study showed that α-mangostin induced apoptotic cell death in COLO 205 cells as indicated by membrane blebbing,chromatin condensation,DNA fragmentation,cell cycle analysis,sub-G1 peak (P < 0.05) and phosphatidylserine exposure.The executioner caspase,caspase-3,the initiator caspase,caspase-8,and caspase-9 were expressed upon treatment with α-mangostin.Further studies of apoptotic proteins were determined by Western blotting analysis showing increased mitochondrial cytochrome c release,Bax,p53 and Bmf as well as reduced mitochondrial membrane potential (P < 0.05).In addition,up-regulation of tBid and Fas were evident upon treatment with α-mangostin (P < 0.01).CONCLUSION:α-Mangostin may be effective as an anti-cancer agent that induced apoptotic cell death in COLO 205 via a link between extrinsic and intrinsic pathways.

Blocking NF-kB nuclear translocation leads to p53-related autophagy activation and cell apoptosis

AIM: To investigate the anti-tumor effects of nuclear factor-κB (NF-κB) inhibitor SN50 and related mechanisms of SGC7901 human gastric carcinoma cells. METHODS: MTT assay was used to determine the cytotoxic effects of SN50 in gastric cancer cell line SGC7901. Hoechst 33258 staining was used to detect apoptosis morphological changes after SN50 treatment. Activation of autophagy was monitored with monodansylcadaverine (MDC) staining after SN50 treatment.Immunofluorescence staining was used to detect the expression of light chain 3 (LC3). Mitochondrial membrane potential was measured using the fluorescent probe JC-1. Western blotting analysis were used to determine the expression of proteins involved in apoptosis and autophagy including p53, p53 upregulated modulator of apoptosis (PUMA), damage-regulated autophagy modulator (DRAM), LC3 and Beclin 1. We detected the effects of p53-mediated autophagy activation on the apoptosis of SGC7901 cells with the p53 inhibitor pifithrin-α. RESULTS: The viability of SGC7901 cells was inhibited after SN50 treatment. Inductions in the expression of apoptotic protein p53 and PUMA as well as autophagic protein DRAM, LC3 and Beclin 1 were detected with Western blotting analysis. SN50-treated cells exhibited punctuate microtubule-associated protein 1 LC3 in immunoreactivity and MDC-labeled vesicles increased after treatment of SN50 by MDC staining. Collapse of mitochondrial membrane potential Δψ were detected for 6 to 24 h after SN50 treatment. SN50-induced increases in PUMA, DRAM, LC3 and Beclin 1 and cell death were blocked by the p53 specific inhibitor pifithrin-α. CONCLUSION: The anti-tumor activity of NF-κB inhibitors is associated with p53-mediated activation of autophagy.

Ginsenoside Rg_3 inhibit hepatocellular carcinoma growth via intrinsic apoptotic pathway

AIM:To investigate the anti-tumor function of ginsenoside Rg3 on hepatocellular carcinoma(HCC) in vitro and in vivo,and its mechanism.METHODS:Hep1-6 and HepG2 cells were treated by Rg3 in different concentrations(0,50,100 and 200 μg/mL) in vitro.After incubation for 0,6,12,24 and 48 h,cell viability was measured by 3-(4,5-dimethylthiazol-2yl)-2,5-diphenyltetrazolium bromide assay.Apoptosis was identified by terminal deoxynucleotidyl transferasemediated dUTP-biotin nick end labeling.Caspase-3 activity was measured by chromophore p-nitroanilide and flow cytometry.Bcl-2 family proteins were ascertained by Western-blotting.Mitochondria membrane potentialwas detected by 5,5',6' 6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolylcarbocyanine iodide.Forty liver tumor-bearing C57Bl6 mice were divided randomly into 4 groups for intra-tumor injection of saline,ginsenoside Rg3,cyclophosphamide(CTX) and ginsenoside Rg3 + CTX combination.RESULTS:The survival time was followed up to 102 d.The mice in the Rg3 + CTX group showed significant increased survival time compared with those in the control group(P < 0.05).Rg3 could inhibit HCC cell proliferation and induce cell apoptosis in vitro in the concentration and time dependent manner.It also induced mitochondria membrane potential to decrease.Caspase-3 activation can be blocked by the inhibitor z-DEVD-FMK.Bax was up-regulated while Bcl-2 and Bcl-XL were down-regulated after Rg3 treatment.CONCLUSION:Our data suggested that Rg3 alone or combined with CTX inhibited tumor growth in vivo and prolonged mouse survival time by inducing HCC cell apoptosis via intrinsic pathway by expression alterations of Bcl-2 family proteins.

Pro-apoptotic effects of tectorigenin on human hepatocellular carcinoma HepG2 cells

AIM:To investigate the effects of tectorigenin on human hepatocellular carcinoma(HCC)HepG2 cells.METHODS:Tectorigenin,one of the main components of rhizome of Iris tectorum,was prepared by simple methods,such as extraction,filtration,concentration,precipitation and recrystallization.HepG2 cells were incubated with tectorigenin at different concentrations,and their viability was assessed by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay.Apoptosis was detected by morphological observation of nuclear change,agarose gel electrophoresis of DNA ladder,and flow cytometry with Hoechst 33342,Annexin V-EGFP and propidium iodide staining.Generation of reactive oxygen species was quantified using DCFH-DA.Intracellular Ca2+was monitored by Fura 2-AM.Mitochondrial membrane potential was monitored using Rhodamine 123.Release of cytochrome c from mitochondria to cytosol was detected by Western blotting.Activities of caspase-3,-8 and-9 were investigated by Caspase Activity Assay Kit.RESULTS:The viability of HepG2 cells treated by tectorigenin decreased in a concentration-and timedependent manner.The concentration that reduced the number of viable HepG2 cells by 50%(IC50)after 12,24 and 48 h of incubation was 35.72 mg/L,21.19 mg/L and 11.06 mg/L,respectively.However,treatment with tectorigenin at 20 mg/L resulted in a very slight cytotoxicity to L02 cells after incubation for 12,24 or 48 h.Tectorigenin at a concentration of 20 mg/L greatly inhibited the viability of HepG2 cells and induced the condensation of chromatin and fragmentation of nuclei.Tectorigenin induced apoptosis of HepG2 cells in a time-and dose-dependent manner.Compared with the viability rate,induction of apoptosis was the main mechanism of the anti-proliferation effect of tectorigenin in HepG2 cells.Furthermore,tectorigenininduced apoptosis of HepG2 cells was associated with the generation of reactive oxygen species,increased intracellular[Ca2+]i,loss of mitochondrial membrane potential,translocation of cytochrome c,and activation of caspase-9 and-3.CONCLUSION:Tectorigenin induces apoptosis of HepG2 cells mainly via mitochondrial-mediated pathway,and produces a slight cytotoxicity to L02 cells.

Conductometric sensor based on oxytetracycline imprinted polymer membrane

A conductometric sensor sensitive to oxytetracycline hydrochloride （OTC.HCI） was developed on the basis of utilizing OTC.HCl imprinted polymer, synthesized under the optimized conditions by using non-covalent imprinted technology with OTC.HCl as a template, MAA as a functional monomer, and EGDMA as a cross-linker, which were the composition of the sensing membrane. The responses increased linearly with the increase of OTC.HCl concentration in the range of 0.99-12.0 μM. The response mechanism of the sensor was also discussed.

Construction of recombinant plasmid pEGFP-C2-L539fs/47 and its expression in HEK293 cells

Objective:To reconstruct pEGFP-C2-L539fs/47,a HERG nonsense mutant in eukaryotic expression plasmid,and observe the fusion protein expressed in HEK293 cells(human embryo kidney cells).Methods:After double digestion of pcDNA3-L539fs/47 and pEGFP-C2-HERG with sbf I and Eco91 I,the small product fragment,from pcDNA3-L539fs/47,was subcloned into the big fragment of pEGFP-C2-HERG under T4 ligase.pEGFP-C2-L539fs/47 was identified by agarose gel electrophoresis and sequencing.pcDNA3-L539fs/47 and pEGFP-C2-L539fs/47 were transiently transfected into HEK293 cells by Lipofect,respectively.The expression of fusion protein in HEK293 cells was detected through immunofluorescence,laser confocal imaging scanning in vivo,Western blot and PCR.Results:Mutation region cDNA fragment(about 1 kb) and target vector fragment(about 7.2 kb) were ligated after purification and gel recovery.Agarose gel electrophoresis and sequencing successfully demonstrated eukaryotic expression plasmid pEGFP-C2-L539fs/47,constructed approximately 8.2 kb,sequencing consistent with template gene.The transfection efficiency of recombinant plasmid by fluorescence microscopy was more than60%.Western blot analysis detected pcDNA3-L539fs/47 expression of the protein size 60 KD,the expression of pEGFP-C2 fusion protein size of approximately 90 KD.The L539fs/47 gene expression in HEK293 cells was significant by PCR analysis.Confocal laser imaging showed that pEGFP-C2-L539fs/47 protein was successfully expressed in cytoplasm and cytomembrane of HEK293 cells.Conclusion:pEGFP-C2-L539fs/47 containing the HERG gene mutant was successfully constructed by double digestion method and expressed fusion protein in HEK293 cells,which laid a foundation for the further study on L539fs/47.

Comparative proteomic study of cervical cancer with different radiotherapy sensitivity

Objective： To investigate the proteornic differences between the high-sensitivity （HS） group and low-sensitivity （LS） group of cervical cancer treated by radiotherapy and confirm the radiotherapy sensitivity associated proteins in early cervical cancer. Methods： The fresh carcinoma tissues were collected from 10 untreated cervical cancer patients and preserved in the -80 ℃ refrigeratory. The tissues were classified into two groups： high sensitivity group （HS） and low sensitivity group （LS）, according to their response to radiotherapy. In the first part of our experiment, protein separating was performed by using two-dimensional gel electrophoresis （2-DE） with Amersham 18 cm linear pH 3-10 immobilized pH gradient （IPG） strips. The images of the gels were acquired by the scanner and then analyzed by using PD-quest7.3 software to find the differentially expression protein-spots in each group. Then the differentially expressed protein-spots was incised from the gels and digested by trypsin. The peptide mass fingerprintings （PMF） was acquired by matrix assisted laser desorption/ionization time-of-flight mass spectrometry （MALDI-TOF-MS） and the proteins were identified by data searching in the Mascot-database. Part of differentially expression proteins were assayed by Western Blot. Results： Most of the gels were clear and successfully analyzed by PD-quest7.3 software. Most of the protein-spots concentrated on the area of 20-100Kda （Mw） and pH4-8. The average number of the protein-spots was 754 ± 64 in HS group and 777 ±48个 in LS group. The match rate was 87.6% between two groups. Five high expression proteins were found in HS group which were low expression in LS group, 3 high expression protein were found in LS group which were low expression in HS group. Reselts of Western Blot were in coincidence to proteomic result. Conclusion： The 2-DE gels image of HS group and LS group with early cervical cancer tissues treated by radiotherapy are successfully acquired. Some differentially expression proteins between the two groups are further confirmed by immunohistochemical assay.

基因工程单克隆抗体N-端氨基酸序列的测定

目的:建立了具有焦谷氨酸封闭N-端的重组抗体N-端氨基酸序列分析方法。方法:利用高温稳定的焦谷氨酸肽酶,基因工程重组单抗样品在高温变性条件下,去除其N-端焦谷氨酸封闭。经还原SDS-PAGE和电印迹后,进行N-端氨基酸序列测定,并与电印迹后在PVDF膜上去封闭处理效果进行比较。结果:测定了17种基因工程单克隆抗体,其中有7个为重链去封闭处理后再进行测序的抗体样品,用2种方法都可顺利去除N-端封闭的焦谷氨酸,从而进行N-端氨基酸序列测定;如果不进行去封闭处理,部分样品无法进行N-端氨基酸序列测定。结论:2种方法都适于N-端具有焦谷氨酸封闭单抗的氨基酸序列分析。

Crosslinked chitosan nanofiber mats fabricated by one-step electrospinning and ion-imprinting methods for metal ions adsorption

The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were fabricated by one-step electrospinning and ion-imprinting methods and their application as adsorbents for metal ions was also investigated.The resulting chitosan nanofiber mats were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),X-ray photoelectron spectroscopy(XPS)and thermal gravimetric analysis(TGA).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were used as adsorbents for the removal of Pb(Ⅱ)ions from aqueous or acid solutions.The effects of p H values,contact time,content of crosslinker(glutaraldehyde)on Pb(Ⅱ)ions adsorption were studied.The results indicated that the Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had the highest adsorption capacity of 110.0 mg/g at p H 7.The kinetic study demonstrated that the adsorption of Pb(Ⅱ)ions followed the pseudo-second-order model.The equilibrium isotherm data showed that the Langmuir model was the most suitable for predicting the adsorption isotherm of the studied system.The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats had good adsorption selectivity,which illustrates the equilibrium adsorption capacity in the order of Pb(Ⅱ)>Cu(Ⅱ)>Zn(Ⅱ)>Cd(Ⅱ)>Ni(Ⅱ).The Pb(Ⅱ)ion-imprinting electrospun crosslinked chitosan nanofiber mats were stable and had good reuse ability.