应用羟基磷灰石层析分离纯化鼠疫菌Pla蛋白的研究

目的应用CHT陶瓷羟基磷灰石层析柱分离纯化鼠疫耶尔森氏菌纤溶酶原激活因子（Pla）。方法优化层析条件,对采用超声破碎结合硫酸铵盐析得到的Pla粗提样品进行纯化,收集纯化中各洗脱峰样品,进行SDS-PAGE。结果上样缓冲液中添加钙离子,可促进Pla与层析柱的结合,经纯化后的Pla,去除了大部分杂蛋白,得到主要由相对分子质量约为31×103、35×103、37×103 Da和3条蛋白带为主的Pla,经软件分析计算,占蛋白总量约80%。结论 CHT陶瓷羟基磷灰石层析能实现对Pla的基本纯化。     

鼠疫菌纤溶酶原激活因子的分离纯化

目的 建立从人工培养的鼠疫菌中分离和纯化纤溶酶原激活因子(Plasminogen activator,Pla)的方法.方法 分别用超声破碎、尿素提取与硫酸铵盐析相结合的方法(简称超声法、尿素法)提取Pla,并分别用离子交换、凝胶过滤两步层析相结合的高效液相色谱和制备电泳纯化Pla,对提取、纯化的Pla进行纤溶酶原激活剂活性检测.结果 鼠疫菌超声破碎上清50%～60%饱和硫酸铵沉淀和尿素浸渍菌粉上清0～10%饱和硫酸铵沉淀,均获得了3条蛋白带[相对分子质量(Mr)约31×103、35×103、37×103].纤溶酶原激活剂活性检测两种方法获得蛋白的溶圈直径分别为6.5、7.2 mm.用高效液相色谱纯化的Pla主要由Mr约31×103、35×1033、37×103的3条蛋白带组成,纤溶酶原激活剂活性检测溶圈直径为5.0 mm.制备电泳纯化的Pla主要由Mr约31×103、35×103、37×103的3条蛋白带组成.条带所在位置还有其他一些低浓度蛋白存在,纤溶酶原激活剂活性检测无溶圈出现.结论 超声法和尿素法可以提取到Pla,后者经高效液相色谱和制备电泳可以达到基本纯化.     

高效液相色谱分离纯化鼠疫菌Pla蛋白

目的用高效液相色谱分离纯化鼠疫菌纤溶酶原激活因子。方法优化离子交换、凝胶过滤,并将2种层析组合实现纯化。结果用高效液相色谱纯化的Pla主要由相对分子质量约31×10^3、35×10^3、37×10^3的3条蛋白带组成,占蛋白总量80％以上。结论Pla经高效液相色谱分离可以达到基本纯化。     

鼠疫耶尔森菌纤维蛋白溶解酶原激活因子蛋白及其特异性片段的原核表达

目的 重组表达鼠疫耶尔森菌纤维蛋白溶解酶原激活因子(Plasminogen activator,Pla)蛋白及其特异性片段并检测其免疫反应性.方法 以鼠疫EV76株为模板,PCR扩增pla、pla-c基因,并与质粒原核表达载体(prokaryotic expression vector,pET)32a(+)连接,将pET32a(+)-pla、pET32a(+)-pla-c分别转化E.coli BL21(DE3)诱导表达;产物经镍离子金属螯合亲和层析纯化,免疫印迹(Western blot)法鉴定其免疫反应性.结果 所表达的Pla蛋白相对分子质量(Mr)为52.8×103,以包涵体形式存在;Pla-c蛋白Mr为24.0×103,以可溶形式存在;这两个蛋白质均可与鼠疫免疫血清产生特异结合反应.结论 所表达的鼠疫菌Pla及其特异性片段具有免疫反应性,为辅助诊断鼠疫提供了选择.     

从表达菌培养液中提取鼠疫菌重组F1抗原

目的从表达鼠疫耶尔森氏菌F1蛋白的诱导培养液中提取纯化重组F1并检测其免疫反应性。方法收集诱导培养后离心去除菌体的培养液,采用硫酸铵沉淀法和PEG浓缩法提取F1蛋白,产物经镍离子金属螯合亲和层析纯化,免疫印迹(Western blot)鉴定其免疫反应性。结果硫酸铵沉淀法和PEG浓缩法均能从培养液中提取到重组F1蛋白,产物经纯化后可与鼠疫疫苗株免疫兔血清和既往鼠疫患者血清发生特异性结合反应。结论该表达菌表达效能较高,在诱导培养液中存在大量具有免疫学活性的重组F1蛋白。     

幽门螺杆菌重组VacA-HpaA IgY的制备

目的:采用基因工程技术大量表达、提纯幽门螺杆菌(H pylori)细胞空泡毒素毒性片段,和黏附素片段的融合蛋白,以此为抗原,制备高效价的抗VacA-HpaA蛋黄抗体(IgY)．方法:大量培养重组菌pQE30-VacA-HpaA- DH5α,诱导表达获得融合蛋白VacA—HpaA, Ni2 -NTA树脂纯化．将纯化的重组蛋白免疫鸡,水稀释法提取IgY,硫酸铵沉淀法纯化浓缩VacA—HpaA IgY．ELISA法测定抗体产生的时间-效价变化,SDS—PAGE分析纯度, Bradford法测定蛋白含量,Western blot检测其分别对VacA和HpaA抗原的特异性,ELISA法检测效价．结果:重组蛋白主要以包涵体形式表达,免疫鸡后提取的IgY可与该蛋白发生免疫反应, IgY效价总体上随免疫时间增加而升高．经纯化、浓缩后,获得纯度为60％左右,效价为1: 12 800的VacA-HpaA IgY,蛋白浓度为22 g／L, Westem blot显示在Mr27 000和Mr30 000处分别有相应条带,ELISA检测与VacA和HpaA反应的效价分别为1:3200和1:6400(P<0．01)．结论:成功制备了高浓度、高效价的抗重组VacA-HpaA的特异性IgY．     

纯化包虫囊液抗原及其应用

本文评价了半饱和硫酸铵盐析纯化包虫囊液抗原的方法及其在诊断中的应用价值。 纯化前后包虫囊液抗原的SDS-PAGE图谱显示,粗制包虫囊液主要蛋白带为20条,经半饱和硫酸铵盐析纯化后为14条,其中尤以66KD组分除去较为彻底。由此可知,盐析使粗制包虫囊液蛋白组分减少,部分纯化了包虫囊液抗原。包虫囊液通过现代免疫化学手段——免疫印迹术(Western blot),可清楚     

基于生物信息学的植物乳酸杆菌表层黏附蛋白的筛选及

目的: 筛选、鉴定及验证植物乳酸杆菌CGMCC No. 1258表层黏附蛋白.方法: 用盐酸胍结合超速离心法提取表层膜蛋白, 通过HRP标记的黏蛋白作抗体Westernblot找到含有黏附蛋白的条带进行质谱分析,生物信息学的TPP软件分析获得可能的蛋白,进行蛋白的分段表达克隆, 并对纯化的蛋白用Western blot进行再次鉴定找到靶蛋白. 同时将黏蛋白连接的sepharose 4B柱提取菌体黏附蛋白, 通过制备的靶蛋白多克隆抗体对菌体黏附蛋白作Western blot进一步验证.结果: 表层蛋白提取后, 电泳及Western blot结果显示30-33 kDa处可及HRP标记的黏蛋白结合的阳性条带, 随后进行质谱及TPP分析获得的蛋白为: (1)A型GTP连接蛋白; (2)丙酮酸氧化酶; (3)细胞分裂激活蛋白; (4)整合膜蛋白;(5)后期能力蛋白. 并进行克隆表达及分段表达, 并在此后的Western blot鉴定中呈强阳性条带显示靶蛋白是整合膜蛋白的第2段. 在应用该靶蛋白制备的多克隆抗体进一步Westernblot验证试验中发现同菌体黏附蛋白相作用的强阳性条带.结论: 植物乳酸杆菌表层黏附蛋白为整合膜蛋白, 并且该蛋白的黏附区域位于其第2段氨基酸序列中.     

鼠疫菌pYC质粒对菌体蛋白质组影响的初步研究

目的 了解鼠疫菌pYC质粒对菌体蛋白质组的作用。方法 将含有pYC质粒的鼠疫菌与不含该质粒的鼠疫菌通过双向电泳的方法进行蛋白质组比对,并将差异蛋白进行质谱鉴定。结果 含有pYC质粒的鼠疫菌与不含该质粒的鼠疫菌的蛋白图谱可识别的蛋白点均在500个以上,两者总体上相似性较高;前者较后者在大小约70×103、等电点5.0左右处,明显多一个蛋白点簇,该蛋白簇经质谱鉴定均为伴侣蛋白GroEL,但该蛋白并非是pYC质粒编码蛋白。结论 pYC质粒对菌体蛋白质组有影响,其编码蛋白pYC_p10与pYC_p11,可能调控GroEL高表达。     

大肠杆菌不耐热肠毒素(LT)无毒突变体mLT63在大肠杆菌中的融合表达及纯化

目的 在大肠杆菌中表达并纯化大肠杆菌不耐热肠毒素无毒突变体mLT63融合蛋白，并探索其免疫反应性。方法采用不同的诱导温度，IPTG浓度，葡萄糖含量，pH值以及不同的培养基优化重组菌TB1（pMAL-c2X-mlt）的表达条件，表达产物经超声粉碎,超声上清经初步盐析、应用直链淀粉亲和层析柱纯化，Western blot鉴定纯化产物的免疫学反应性。结果 融合蛋白在诱导表达产物中的含量达到16．11％,纯化产物的纯度达到72．58％。纯化产物能够被抗CT血清所识别。结论 成功表达并纯化出了大肠杆菌不耐热肠毒素无毒突变体mLT63，获得了纯度较高并具有良好免疫反应性的融合蛋白。     

IgE reactivity to profilin in Platanus acerifolia pollen-sensitized subjects with plant-derived food allergy.

BACKGROUND: The presence of profilin-specific IgE antibodies is a cause of cross-reactivity between botanically-unrelated allergen sources. Recently, the association between Platanus acerifolia pollinosis and plant-derived food allergy has been described. The aim of this study was to ascertain whether the P. acerifolia profilin is involved in such cross-reactivity. METHODS: Twenty-three patients suffering from Platanus acerifolia pollinosis and plant-derived food allergy were evaluated in an allergy department. Specific IgE levels to P. acerifolia pollen, P. acerifolia profilin and food extracts were measured. Molecular masses of IgE-binding proteins were calculated by Western blotting and cross-reactivity studies among P. acerifolia profilin and different food extracts were evaluated by Enzyme AllergoSorbent Test (EAST)-inhibition assays. Also, EAST-inhibition assays with the two known P. acerifolia allergens, Pla a 1 and Pla a 2, were performed. RESULTS: Surprisingly, a high IgE-binding prevalence (90%) of P. acerifolia profilin was found. EAST-inhibition showed high inhibition values when Platanus acerifolia pollen extract was used as free phase and plant-derived food extracts as solid phase, whereas the other way round showed low inhibition values. IgE reactivity to profilin was studied using a pool of patient sera, by EAST-inhibition assays with hazelnut, apple peel, peanut, chickpea and peanut extracts as solid phase and no inhibition was obtained when P. acerifolia profilin was used as inhibitor phase. The same results were obtained when purified Pla a 1 and Pla a 2 were also used as inhibitor phase. CONCLUSIONS: The clinical association observed between Platanus acerifolia pollen and plant-derived food could be explained by the in vitro IgE cross-reactivity detected by EAST-inhibition. However, it appears that neither P. acerifolia profilin nor the two major allergens described (Pla a 1 and Pla a 2) can explain such a strong cross-reactivity.     

日本血吸虫感染兔血清蛋白质质谱分析

目的通过对感染日本血吸虫兔血清进行蛋白质质谱分析,确定有潜在诊断意义的标志蛋白,为日本血吸虫病血清学诊断提供理论依据。方法取不同感染时期的兔血清,利用WCX磁珠纯化试剂盒富集血清蛋白,应用基质辅助激光解吸电离飞行时同质谱（MAIDI—TOF-MS）技术进行分析。结果与正常兔血清蛋白指纹图谱比较,在Mr1000-12000区段,不同感染时期实验兔血清分析共有63个蛋白峰,其中7种蛋白有显著差异,利用BrukerClinProTools软件分析,在感染后第6天,Mr1787蛋白有显著上调（P〈O．05）;感染后第9天,Mr2834蛋白有极显著上调（P〈0．01）,另外Mr3483蛋白有显著上调（P〈0.05）,Mr4018蛋白有显著下调（P〈0.05）;在感染后第12天,Mr3151蛋白有显著下调（P〈0.05）,而Mr4018蛋白在感染后第12天,则出现极显著下调（P〈0.01）,两者趋势一直持续至感染后第30天。家兔感染后第9～12天,血清中Mr3530蛋白有显著上调（P〈0.05）,Mr1716蛋白显著下调（P〈0.05）;第12~30天血清中Mr3151、3530蛋白有显著下调（P均〈0.05）。结论MALDI-TOF-MS结合磁珠富集技术可发现及检测日本血吸虫病具有潜能的早期生物标志物,为从蛋白质水平研究日本血吸虫病免疫诊断及寻找新的治疗靶位奠定了基础。     

Influence of lung injury on pulmonary wedge-left atrial pressure correlation during positive end-expiratory pressure ventilation

The correlation between pulmonary artery wedge pressure (Pw) and left atrial pressure (Pla) requires a continuous fluid column between the catheter tip and the left atrium. We hypothesized that lung injury may protect the fluid column from the collapsing effects of increased airway pressure. Correlation between Pw and Pla would then depend on catheter tip location in injured versus normal lung regions. In 7 anesthetized dogs with unilateral acid pneumonitis, we compared Pla and simultaneous Pw measurements from pulmonary artery catheters located in injured and normal lungs at different levels of positive end-expiratory pressure (PEEP). Studies were repeated in 10 dogs with normal lungs and 5 dogs with bilateral acid pneumonitis. In supine dogs with unilateral lung injury, Pw from the injured lung more accurately reflected Pla than did Pw obtained from the normal lung at PEEP levels of 7 mmHg or higher, in contrast to data from dogs with normal lungs or equally injured lungs. Discrepancies between Pw and Pla at PEEP levels of 7 and 11 mmHg from the normal lung were corrected when that lung was placed in the dependent position to increase venous pressure at the catheter tip. A good Pw-Pla correlation was not guaranteed by catheter tip location below the level of the left atrium during PEEP ventilation. We conclude that the continuity of the fluid column was protected by lung injury. Although Pw-Pla differences from the normal lung were modest at the levels of PEEP that are usually optimal for gas exchange in uneven lung injury, it is recommended that the injured lung should not be avoided during insertion of the balloon-tipped catheter.     

Effects of alveolar hypoxia on lung fluid and protein transport in unanesthetized sheep.

To determine whether hypoxia directly affects pulmonary microvascular filtration of fluid or permeability to plasma proteins, we measured steady state lung lymph flow and protein transport in eight unanesthetized sheep breathing 10% O2 in N2 for 4 hours. We also studied three sheep breathing the same gas mixture for 48 hours. We surgically prepared the sheep to isolate and collect lung lymph and to measure average pulmonary arterial (Ppa) and left atrial (Pla) pressures. We placed a balloon catheter in the left atrium to elevate Pla. After recovery, the sheep breathed air through a tracheostomy for 2-4 hours, followed by 4 or 48 hours of hypoxia. In 13 4-hour studies, the average arterial PO2 fell from 97 to 38 torr; Ppa rose from 20 to 33 cm H2O; and lung lymph flow and lymph protein flow were unchanged. We also found that during 48-hour hypoxia, with a sustained elevation in Ppa and a decline in Pla, lymph flow and protein flow did not increase. In four sheep, we also raised Pla for 4 hours, followed by 4 hours of hypoxia with elevated Pla. Again, despite the added stress of elevated Pla, we found that lymph flow and lymph protein flow remained constant during hypoxia. We conclude that severe alveolar hypoxia, for 4 or 48 hours, alone or with increased pulmonary microvascular pressure, produced no change in lung fluid filtration or protein permeability, a finding supported by normal postmortem histology and extravascular lung water content.     

Cyclic AMP-dependent phosphorylation of high molecular mass proteins in pig thyroid cells

Four high molecular mass (H Mr) proteins were found to be phosphorylated in a cyclic AMP-dependent manner in both partially purified pig thyroid membrane fractions and in pig thyroid cells in culture. These phosphoproteins did not correspond to major cellular proteins; they were found in both soluble and particulate subfractions of homogenates from cultured thyroid cells. The molecular mass of the 4 proteins named HMr1 to HMr4 determined by polyacrylamide gel electrophoresis in the in the presence of sodium dodecylsulfate was about 310 000 for HMr1, 250 000 for HMr2, 240 000 for Hmr3 and 220 000 for HMr4. HMr1 comigrated with brain MAP1, whereas HMr3 and HMr4 had the same mobility as alpha-and beta-spectrins, respectively. The 4 high molecular mass phosphoproteins are substrates of cyclic AMP-dependent protein kinase(s) since (a) their phosphorylation was increased by cyclic AMP and not by cyclic GMP or calcium alone or calcium in the presence of calmodulin or phospholipid; (b) the effect of cyclic AMP was prevented by the thermostable inhibitor of cyclic AMP-dependent protein kinases; (c) the purified catalytic subunit of cyclic AMP-dependent protein kinases markedly phosphorylated the 4 HMr proteins. The 32P-labeling of HMr proteins using either endogenous cyclic AMP-dependent protein kinase or the purified catalytic subunit was always lower in cells cultured in the presence of TSH (reassociated in follicle-like structures) than in freshly dispersed cells or cells cultured in basal conditions (cells in monolayer). These results suggest that the 4 high molecular mass thyroid phosphoproteins represent structural components, the phosphorylation of which could vary with the cellular organization.     

Effects of alveolar hypoxia during partial mitral valve obstruction in unanesthetized sheep

The effects of elevated left atrial pressure (Pla) on the pulmonary hemodynamic responses to hypoxia and infused prostaglandin-H2 analog (PGH2-A) were studied in 10 chronically instrumented unanesthetized sheep. Sheep were studied with isocapnic hypoxia (fraction of inspired O2, 0.12) or infused PGH2-A (0.2 to 1.0 micrograms X kg-1 X min-1 adjusted to increase pulmonary artery pressure (Ppa) by approximately 15 cm H2O) when Pla was normal or elevated to 10 or 20 cm H2O. The Pla was elevated by inflating a Foley catheter positioned in the mitral valve orifice. Elevation of Pla did not block the increase in Ppa or cardiac output (CO) caused by hypoxia but did block the increase in pulmonary vascular resistance (PVR). When Pla was elevated to 10 or 20 cm H2O, hypoxia caused Pla to increase further, and PGH2-A caused Ppa and PVR to increase whether Pla was elevated or not; PGH2-A did not cause CO to increase or Pla to increase further under any experimental condition. Neither hypoxia nor PGH2-A had any effect on left ventricular end-diastolic pressure under any experimental condition. We hypothesize that when Pla is elevated, the increase in CO may dilate the pulmonary circulation, obscuring hypoxic vasoconstriction. When Pla is elevated, the direct effects of hypoxic pulmonary vasoconstriction cannot overcome the increased intraluminal pressure, and PVR does not increase. The pulmonary vessels are still able to respond to a potent vasoconstrictor such as PGH2-A when Pla is elevated. We conclude that the further increase in Pla caused by hypoxia when Pla is elevated is primarily due to increased flow across a mitral valve behaving as a relatively fixed resistor.     

Left atrial pressure can be accurately transmitted to the pulmonary artery despite zone 1 conditions

Pulmonary arterial occlusion pressure is not thought to reflect left atrial pressure (Pla) when alveolar pressure (PA) exceeds pulmonary venous pressure because alveolar capillaries collapse and the required continuous fluid column between the pulmonary artery and left atrium is interrupted. However, arterial-to-venous flow can occur when PA exceeds both the pulmonary arterial pressure (Ppa) and pulmonary venous pressure (i.e., in Zone 1 conditions), indicating the existence of a continuous patent vascular channel. Accordingly, Ppa should reflect Pla under these conditions. To investigate this connection cannulas were placed in the pulmonary arteries and left atria of eight excised rabbit lungs. Ppa and Pla were set 5 cm H2O above PA, which ranged from 0 to 25 cm H2O. Pla was then reduced in 2 to 4 cm H2O decrements while recording Ppa when arterial-to-venous flow ceased. At all PAs greater than 0 cm H2O, Pla was accurately reflected by the Ppa when both were exceeded by PA. The greater the PA, the lower the Ppa could track Pla below PA. Pla can be accurately measured by a pulmonary arterial catheter under Zone 1 conditions.     

Small heat shock protein of Methanococcus jannaschii, a hyperthermophile

Small heat shock proteins (sHSPs) belong to a family of 12- to 43-kDa proteins that are ubiquitous and are conserved in amino acid sequence among all organisms. A sHSP homologue of Methanococcus jannaschii, a hyperthermophilic Archaeon, forms a homogeneous multimer comprised of 24 monomers with a molecular mass of 400 kDa in contrast to other sHSPs that show heterogeneous oligomeric complexes. Electron microscopy analysis revealed a spherically shaped oligomeric structure ≈15–20 nm in diameter. The protein confers thermal protection of other proteins in vitro as found in other sHSPs. Escherichia coli cell extracts containing the protein were protected from heat-denatured precipitation when heated up to 100°C, whereas extracts from cells not expressing the protein were heat-sensitive at 60°C. Similar results were obtained when purified sHSP protein was added to an E. coli cell lysate. The protein also prevented the aggregation of two purified proteins: single-chain monellin (SCM) at 80°C and citrate synthase at 40°C.