人嗜中性白细胞活化蛋白-1/白细胞介素-8合成基因的修正及修正基因在大肠杆菌中的表达

本文采用寡核苷酸介导的定位诱变技术修正了人嗜中性白细胞活化蛋白-1/白细胞介素-8合成基因中出现的合成错误,在该基因编码区的201位插入了原来缺失的G残基,从而使之恢复正确读框。经对修正基因进行DNA全序列测定,表明定位诱变的结果符合设计要求。在此基础上,利用原核高效表达载体pBV220在P_RP_L串联启动子的控制下在大肠杆菌中对该基因进行了表达,并测定了重组人嗜中性白细胞活化蛋白-1/白细胞介素-8的嗜中性白细胞趋化活性。本工作为开展人嗜中性白细胞活化蛋白-1/白细胞介素-8基因工程及蛋白质工程的研究奠定了基础。     

重组人白细胞介素4的纯化及N端氨基酸序列分析

本文对重组人白细胞介素4高效表达克隆pBV220/hIL-4a的表达产物进行了纯化,升对纯化的人IL-4进行了N端氨基酸序列分析。人IL-4基因表达产物在大肠杆菌中以不溶性包涵体形式存在,经过超声破菌、包涵体抽提、复性浓缩、离子交換和凝胶过滤层析一系列纯化步骤,终产物纯度达98％以上,按蛋白总量计算回收率为14％,比活性达2×10~6单位/mg蛋白。通过测定纯化人IL-4的N端16个氮基酸序列,与由其DNA序列推导的氨基酸序列完全一致。本文为重组人IL-4的批量生产奠定了基础。     

一种来源于蜗牛酶的β-葡萄糖苷酶的纯化

通过DEAE-Sepharose离子交换分段层析、DEAE-Sepharose离子交换梯度层析和Sephadex G-100凝胶过滤层析三种方法的联用,从中华白玉蜗牛消化酶中提纯出一种β-葡萄糖苷酶。该酶在SDS-PAGE上呈单一蛋白质条带。应用SDS-PAGE和凝胶过滤层析测定其分子量,提示该酶是由4个分子量为110~115 kD的相同亚基组成的同源四聚体。pNPG为底物的动力学参数Km和Vmax分别为0.182 mmol/L和0.189μmol/(min.mg)。     

凝胶过滤与镍柱亲和纯化金葡菌α-溶血素重组蛋白的生物学特性比较

以在宿主菌株BL21(DE3)中成功表达的重组金黄色葡萄球菌α-溶血素蛋白为研究对象,分析比较通过凝胶过滤层析(Gel filtration chromatography)和镍柱亲和层析纯化试剂盒(Ni-NTA spin columns)纯化所得到的重组蛋白的蛋白含量和生物特性方面的差异.SDS-PAGE分析检测纯化产物,Bradford法测定蛋白含量,兔红细胞测定半数溶血效价,结果显示这2种方法得到的纯化产物在53 kD处均呈现单一清晰带,达电泳级纯度.与此同时,凝胶过滤对目的蛋白的纯化率为14.04%,蛋白含量为0.337 mg/mL,溶血活性为1519 HU/mg;镍柱亲和层析的纯化率为17.5%,蛋白含量为0.35 mg/mL.溶血活性为1463 HU/mg.由此可见,凝胶过滤得到的纯化产物在蛋白含量和蛋白活性方面丝毫不亚于镍柱亲和层析纯化试剂盒.     

蛇毒类凝血酶calobin在毕赤酵母中的表达

蛇毒类凝血酶是临床上防治血栓栓塞性疾病的有效药物。参照朝鲜蝮蛇(Agkistrodon caliginosus,Korean Viper)类凝血酶calobin基因序列(GenBank AccessionNo.U32937.1),将人工合成的calobin基因克隆到酵母表达载体pPICZαA,于毕赤酵母中表达,得到了分子量约为32kD的重组calobin蛋白,经甲醇诱导培养,表达产物可获得3.5g/L的高表达量。重组蛋白经过阴离子交换柱Q-Sepharose Fast Flow和分子筛Sephacryl-S-100凝胶过滤层析等纯化步骤进行了初步纯化。纯化后的重组calobin可以在纤维蛋白原平板上形成水解圈,经SDS-PAGE实验显示,重组蛋白能水解纤维蛋白原的Aα链,产生一条约40kD左右的降解带。在实验中未能发现重组calobin对纤维蛋白原的凝固作用。     

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。     

银杏种仁中一种抗氧化活性蛋白的纯化及性质

银杏种仁经破碎,提取缓冲液4℃浸取后离心得上清液。上清液经硫酸铵沉淀,DEAE-52离子交换层析,MonoQ离子交换层析,UltroGelACA-54凝胶过滤层析后,分离得到一种具有抗氧化活性的蛋白。该蛋白经UltroGelACA-54凝胶过滤层析测定分子量为60 kD,经PAGE和SDS-PAGE鉴定均为单一蛋白质条带。SDS-PAGE测定其亚基分子量为10 kD。该蛋白具有一定的还原能力和清除超氧阴离子自由基及DPPH自由基能力,并在30～60℃温度下具有良好的稳定性。     

重组小鼠白细胞介素-33的原核表达制备及其粘膜免疫佐剂活性

目的:白细胞介素(IL)-33对树突状细胞、巨噬细胞及T细胞等免疫细胞具有重要调控作用。利用大肠杆菌制备重组小鼠的IL-33,并初步考察其作为粘膜免疫佐剂应用的潜能与特点。方法:以IPTG诱导硫氧还蛋白(Trx)/IL-33融合蛋白在大肠杆菌DH5α中的表达,并通过QSepharose离子交换和Ni~(++)金属螯合亲和层析纯化Trx/IL-33,进一步经肠激酶切割获得成熟形式的IL-33。重组HBcAg混合纯化的IL-33后经滴鼻免疫小鼠,考察HBcAg特异的IgA及IgG_1、IgG_(2a)的应答。结果:纯化的重组IL-33具有与标准品相当的促巨噬细胞RAW264.7表达TNF-α的体外细胞生物学活性。作为佐剂可显著增强滴鼻粘膜免疫激发的不同粘膜组织中HBcAg特异的IgA应答,以及血清与支气管肺泡灌洗液中特异IgG_1的应答水平,而抑制IgG_(2a)应答。结论:利用大肠杆菌可制备活性IL-33,其具有粘膜免疫佐剂的应用潜能。     

人小肠三叶因子在大肠杆菌中的表达

利用PCR技术将人小肠三叶因子(hITF)基因重组入表达载体pGEX-4T-1,构建了融合蛋白GST-hITF的重组表达质粒pGTF,在大肠杆菌中诱导表达。表达的融合蛋白经亲和层析、凝血酶切和凝胶过滤层析得到纯化的hITF蛋白。测定了重组蛋白的氨基酸组成、分子量及其对酸和蛋白酶的抗性。Western印迹表明重组蛋白具有hITF的抗原性,并对大鼠胃溃疡具有明显的预防和保护作用。     

猪白细胞介素18成熟蛋白基因的克隆与表达

目的克隆猪白细胞介素18(pIL-18)成熟蛋白基因,并在植物乳杆菌(Lb.plantarum)NC8中进行表达。方法通过RT-PCR方法从猪脾脏细胞中扩增出pIL-18成熟蛋白基因,克隆到T载体pMD18-T后测序;将阳性基因片段克隆至大肠埃希菌-乳酸菌穿梭表达载体pSIP-409构建重组表达载体pSIP-409-IL-18,进行酶切和PCR鉴定;应用电穿孔技术将其转化至Lb.plantarum NC8中,经SppIP诱导表达后,进行SDS-PAGE及Western-blot分析。结果经测序,pIL-18成熟蛋白基因核苷酸长度为579 bp,编码193个核苷酸;酶切和PCR鉴定证明成功构建了重组表达载体pSIP-409-IL-18;SDS-PAGE及Western-blot分析表明重组菌表达了18 kD的融合蛋白,该重组蛋白可以与鼠抗猪IL-18多克隆抗体反应。结论成功克隆了pIL-18成熟蛋白基因,并获得有生物活性的pIL-18重组乳酸菌,为研制开发IL-18重组乳酸菌制剂奠定基础。     

IL-1 alpha or tumor necrosis factor-alpha stimulate release of three NAP-1/IL-8-related neutrophil chemotactic proteins in human dermal fibroblasts

Human dermal fibroblasts in culture secrete three protein-like neutrophil chemotactic factors, when stimulated either with human rIL-1 alpha or IL-1 beta; not, however, after incubation with LPS. These three fibroblast-derived neutrophil-activating proteins (FINAP) could be purified by subsequently performed reversed phase and size exclusion HPLC. By high resolution SDS-PAGE, all the proteins were shown to migrate with an Mr of 6,700 (alpha-FINAP), 3,600 (beta-FINAP), and 5,300 (gamma-FINAP). All purified cytokine preparations were found to be chemotactic for human neutrophils. In addition, all FINAP induced release of lysosomal enzymes in neutrophils. Deactivation of chemotaxin-elicitable enzyme release showed cross-desensitization of all FINAP with NAP-1/IL-8. Western blot analysis of alpha-FINAP by using mAb against neutrophil-activating protein (NAP)-1/IL-8 reveals immunologic cross-reactivity with NAP-1/IL-8. By amino-terminal amino acid sequence analysis alpha-FINAP could be identified as the 77-residue extended form of NAP-1/IL-8 containing the 79-residue form as a minor contaminant. Whereas beta-FINAP has been found to be a truncation product of alpha-FINAP, gamma-FINAP shows identity with authentic melanoma growth stimulatory activity with respect to retention time upon reversed phase HPLC, high resolution SDS-PAGE, and biologic properties, as well as amino-terminal amino acid sequence. These data show that human dermal fibroblasts may actively participate in inflammatory reactions by secretion of proinflammatory cytokines.     

Neutrophil attractant/activation protein-1 and monocyte chemoattractant protein-1 in rabbit. cDNA cloning and their expression in spleen cells

Rabbit neutrophil attractant/activation protein-1 (NAP-1) and monocyte chemoattractant protein-1 (MCP-1) were investigated. Rabbit spleen cells stimulated with 5 micrograms/ml of Con A produced both neutrophil and monocyte chemotactic activity. Physicochemical characteristics of those activities obtained by HPLC gel filtration and HPLC chromatofocusing were very similar to those of human NAP-1 and MCP-1, suggesting that rabbit spleen cells produce NAP-1 and MCP-1 after Con A stimulation. A cDNA library was constructed from mRNA purified from Con A-stimulated rabbit spleen cells and screened with oligonucleotide probes. By two rounds of screening, NAP-1 and MCP-1 cDNA were cloned. NAP-1 cDNA comprises 1500 bp with an open reading frame that encodes for a 101-amino acid protein highly similar to human NAP-1. MCP-1 cDNA comprises 607 bp with an open reading frame that encodes for a 124-amino acid protein highly similar to human MCP-1. Expression of NAP-1 and MCP-1 mRNA by rabbit spleen cells was studied. Both Con A- and LPS-stimulated spleen cells expressed NAP-1 and MCP-1 mRNA, but the kinetics of expression were different. Con A rapidly induced high NAP-1 and MCP-1 mRNA expression. LPS also rapidly induced NAP-1 mRNA expression, but high MCP-1 mRNA expression was not observed until 15 h after stimulation. Immunoprecipitation of metabolically labeled NAP-1 and MCP-1 with anti-human NAP-1 or MCP-1 polyclonal antibodies was attempted. Immunoprecipitated rabbit NAP-1 with a molecular mass of about 7 kDa was detected by SDS-PAGE and radioautography, but MCP-1 was not. Cloned rabbit NAP-1 and MCP-1 will give us opportunities to study the role of NAP-1 and MCP-1 in vivo.     

Chemical synthesis, purification, and characterization of two inflammatory proteins, neutrophil activating peptide 1 (interleukin-8) and neutrophil activating peptide

Two recently identified pro-inflammatory proteins, namely, neutrophil activating peptide 1 (NAP-1) [also termed interleukin-8 (IL-8)] and NAP-2, were chemically synthesized, purified, and characterized. The fully protected NAP-1/IL-8 (72 residues) and NAP-2 (70 residues) peptide chains were assembled by automated solid-phase methods with average stepwise yields of 99.5 and 99.3%, resulting in overall chain assembly yields of 70 and 62%, respectively. Deprotection resulted in crude products, which were allowed to fold by air oxidation, and were purified by two cycles of reverse-phase high-pressure liquid chromatography, yielding 27 mg of NAP-1/IL-8 and 22 mg of NAP-2. Purity was established by reverse-phase high-pressure liquid chromatography and isoelectric focusing, and the primary structures of the purified products were verified by using mass spectrometry and Edman sequencing methods. Synthetic and recombinant NAP-1/IL-8 were equally active on human neutrophil granulocytes as determined by measuring the induction of cytosolic free calcium, elastase release, and chemotaxis. Synthetic NAP-2 was equivalent to purified natural NAP-2 in the elastase release and calcium mobilization assays, but it was consistently less potent (3-5-fold) as a stimulus of chemotaxis, perhaps indicative of additional chemotactic components in the natural preparation. The results indicate that by chemical synthesis these cytokines can be obtained in purity and quantities suitable for further structural analysis, as well as functional studies both in vivo and in vitro.(ABSTRACT TRUNCATED AT 250 WORDS)     

百合巯基蛋白酶抑制剂的纯化及部分性质研究

百合的鳞茎中含有一种对木瓜蛋白酶有强抑制作用的巯基蛋白酶抑制剂．百合的鳞茎经浸取加热处理,木瓜蛋白酶偶联的Ｓｅｐｈａｒｏｓｅ４Ｂ柱亲和层析和ＳｅｐｈａｄｅｘＧ－１００分子筛层析,可获得在ＰＡＧＥ和ＳＤＳ－ＰＡＧＥ均为单一蛋白带的百合巯基蛋白酶抑制剂（ＣＰＩ）．此ＣＰＩ为单链蛋白,含有０．３０７％的中性糖;Ｎ端氨基酸为Ｉｌｅ;ＳＤＳ－ＰＡＧＥ测得亚基分子量为１２０００;ＳｅｐｈａｄｅｘＧ－１００测得分子量为１２５００．百合ＣＰＩ在１００℃内和ｐＨ２～１２范围内非常稳定;对木瓜蛋白酶的抑制属竞争性抑制类型,其Ｋｉ值为１．１５×１０~（－９）ｍｏｌ／Ｌ,对木瓜蛋白酶的抑制摩尔比为８．５：１．     

蜗牛酶中一种人参皂苷Rb1水解酶的分离纯化

通过DEAE-Sepharose离子交换分段层析,DEAE-Sepharose离子交换梯度层析和SephadexG-100凝胶过滤层析三种方法的联用从中华白玉蜗牛消化酶中分离出一种人参皂苷Rb1水解酶。分离后该酶在SDS-PAGE上呈单一蛋白质务带。应用SDS-PAGE和凝胶过滤层析对分子量的测定,提示该酶是由4个分子量为110～115kD的相同亚基组成的同源四聚体。Rb1为底物的动力学参数Km和Vmax分别为0．790mmol／L和10．192μmol／min／mg。该酶对人参皂苷Rb1糖键进行有选择的水解,可水解人参皂苷Rb1C50位的一个糖苷键生成人参皂苷Rd。     

Neutrophil-activating peptide 2 and gro/melanoma growth-stimulatory activity interact with neutrophil-activating peptide 1/interleukin 8 receptors on human neutrophils

Neutrophil-activating peptide 1/interleukin 8 (NAP-1/IL-8), neutrophil-activating peptide 2 (NAP-2), and gro/melanoma growth-stimulatory activity (gro/MGSA) are potent inflammatory cytokines with homologous structure and similar neutrophil-activating properties. Receptors on human neutrophils that interact with these peptides were studied. Analysis of 125I-NAP-1/IL-8 binding at 0-4 degrees C revealed 64,500 +/- 14,000 receptors/cell with an apparent Kd of 0.18 +/- 0.07 nM (mean +/- S.D. of six independent experiments). Unlabeled NAP-1/IL-8, NAP-2, and gro/MGSA competed with 125I-NAP-1/IL-8 for binding to human neutrophils. Competition with increasing concentrations of unlabeled NAP-2 and gro/MGSA resolved two classes of NAP-1/IL-8 binding sites: about 70% of them bound NAP-2 and gro/MGSA with high affinity (Kd: 0.34 +/- 0.2 and 0.14 +/- 0.02), while 30% were of low affinity (Kd: 100 +/- 20 and 130 +/- 10 nM). Different binding sites, however, were not apparent upon competition with unlabeled NAP-1/IL-8, suggesting that both classes of receptors have similar affinities for NAP-1/IL-8. The existence of two receptors was also suggested by ligand cross-linking and cross-desensitization experiments. Two neutrophil membrane proteins with apparent Mr of 66,000-74,000 and 42,000-46,000 became cross-linked to 125I-NAP-1/IL-8, and the labeling was decreased when excess NAP-1/IL-8, NAP-2, or gro/MGSA was present. Stimulation of neutrophils with NAP-1/IL-8 resulted in desensitization toward a subsequent challenge with NAP-2 or gro/MGSA as shown by the rise in cytosolic free calcium. By contrast, following primary stimulation with NAP-2 or gro/MGSA, responses to NAP-1/IL-8 were only moderately attenuated, supporting the existence of NAP-1/IL-8 receptors which bind NAP-2 or gro/MGSA with low affinity. In conclusion, our results demonstrate that NAP-2 and gro/MGSA act upon human neutrophils by directly interacting with two classes of receptors for NAP-1/IL-8.     

Purification and characterization of selenium-containing phycocyanin from selenium-enriched Spirulina platensis

A fast protein liquid chromatographic method for purification of selenium-containing phycocyanin (Se-PC) from selenium-enriched Spirulina platensis was described in this study. The purification procedures involved fractionation by ammonium sulfate precipitation, DEAE-Sepharose ion-exchange chromatography and Sephacry S-300 size exclusion chromatography. The purity ratio (A620/A280) and the separation factor (A620/A655) of the purified Se-PC were 5.12 and 7.92, respectively. The Se concentration of purified Se-PC was 496.5 microg g(-1) protein, as determined by ICP-AES analysis. The purity of the Se-PC was further characterized by UV-VIS and fluorescence spectrometry, SDS-PAGE, RP-HPLC and gel filtration HPLC. The apparent molecular mass of the native Se-PC determined by gel filtration HPLC was 109 kDa, indicating that the protein existed as a trimer. SDS-PAGE of the purified Se-PC yielded two major bands corresponding to the alpha and beta subunits. A better separation of these two subunits was obtained by RP-HPLC. Identification of the alpha and beta subunits separated by SDS-PAGE and RP-HPLC was achieved by peptide mass fingerprinting (PMF) using MALDI-TOF-TOF mass spectrometry.     

NAP-2 is part of multi-protein complexes in HeLa cells

We previously reported that a complex of nuclear proteins from HeLa cells, among them histone H1 and casein kinase 2 co-eluted from immobilized nucleosome assembly protein 2 (NAP-2)-Sepharose. Here, using HeLa cell nuclear extracts, we found NAP-2 migrates in a blue-native polyacrylamide gel with an apparent molecular weight of 300 kDa. HeLa cell NAP-2, labeled in vivo with radioactive orthophosphate, co-precipitated with at least two phosphoproteins, with an apparent mass of 100 and 175 kDa, respectively, as determined by SDS-PAGE. NAP-2 from total HeLa cell extract co-purified with other proteins through two sequential chromatographic steps: first, a positively charged resin, Q-Sepharose, was used, which purified NAP-2 more easily with other proteins that eluted as a single peak at 0.5 M NaCl. This fraction possessed both relaxing and supercoiling activities, and it was able to assemble regularly spaced nucleosomes onto naked DNA in an ATP-dependent manner. Second, a negatively charged resin (heparin) was used, which retained small amounts of NAP-2 (a very acidic polypeptide) and topoisomerase I. This fraction, although able to supercoil relaxed DNA, did so to a lesser extent than the Q-Sepharose fraction. The data suggest that NAP-2 is in complex(es) with other proteins, which are distinct from histones.     

Neutrophil-activating peptide 1/interleukin 8 mRNA expression and protein secretion by human monocytes: effect of cyclosporin A

Neutrophil-activating peptide 1/interleukin 8 (NAP-1/IL-8) is a recently described cytokine with potent chemotactic activity for human neutrophil granulocytes (PMN) and T cells. In psoriasis, a chronic hyperproliferative and inflammatory skin disorder, PMN and T cells are found as prominent cells in the inflammatory infiltrate of the lesions; however, monocytes were shown to be the first cells invading a newly formed plaque. NAP-1/IL-8 was found to be present in high amounts in the skin and in scale material of psoriatic patients. Psoriasis responds well to systemic treatment with cyclosporin A (CsA), an immunosuppressive peptide. Therefore, we addressed the question of whether the clinical improvement of psoriatic patients during CsA therapy may be due to an inhibition of NAP-1/IL-8 production and secretion from monocytes. Purified human monocytes were stimulated by lipopolysaccharide in the presence or absence of various concentrations of CsA. Production of NAP-1/IL-8 was determined as expression of specific mRNA by fluorescent in situ hybridization. Secreted peptide was measured by bioassay (PMN chemotaxis) and enzyme-linked immunosorbent assay (ELISA) using specific monoclonal antibodies. The results show that CsA neither inhibited mRNA expression for NAP-1/IL-8 nor secretion of the peptide. These findings support the hypothesis that the pharmacological effect of CsA may be restricted to the inhibition of T-cell activation and proliferation.