Renaturation with simultaneous purification of rhG-CSF from Escherichia coli by ion exchange chromatography

Protein refolding is a key step for the production of recombinant proteins, especially at large scales, and usually their yields are very low. Application of liquid chromatography to protein refolding is an exciting step forward for this field. In this work, recombinant human granulocyte colony-stimulating factor (rhG-CSF) expressed in Escherichia coli was renatured with simultaneous purification by ion exchange chromatography (IEC) with a Q Sepharose FF column. Several chromatographic parameters affecting the refolding yield of the denatured/reduced rhG-CSF, such as the urea concentration, pH value, concentration and ratio of reduced/oxidized glutathione in the mobile phase, as well as the flow rate of the mobile phase, were investigated in detail and indicated that the urea concentration and the pH value were of great importance. At the optimal conditions, the renatured and purified rhG-CSF was found to have a specific bioactivity of 3.0 x 10(8) IU/mg, a purity of 96%, and a mass recovery of 49%. Compared with the usual dilution method, the IEC method developed here is more effective for rhG-CSF refolding in terms of specific bioactivity and mass recovery.     

One‐step refolding and purification of recombinant human tumor necrosis factor‐α (rhTNF‐α) using ion‐exchange chromatography

Protein refolding is a key step for the production of recombinant proteins, especially at large scales, and usually their yields are very low. Chromatographic‐based protein refolding techniques have proven to be superior to conventional dilution refolding methods. High refolding yield can be achieved using these methods compared with dilution refolding of proteins. In this work, recombinant human tumor necrosis factor‐α (rhTNF‐α) from inclusion bodies expressed in Escherichia coli was renatured with simultaneous purification by ion exchange chromatography with a DEAE Sepharose FF column. Several chromatographic parameters influencing the refolding yield of the denatured/reduced rhTNF‐α, such as the urea concentration, pH value and concentration ratio of glutathione/oxidized glutathione in the mobile phase, were investigated in detail. Under optimal conditions, rhTNF‐α can be renatured and purified simultaneously within 30 min by one step. Specific bioactivity of 2.18 × 10⁸ IU/mg, purity of 95.2% and mass recovery of 76.8% of refolded rhTNF‐α were achieved. Compared with the usual dilution method, the ion exchange chromatography method developed here is simple and more effective for rhTNF‐α refolding in terms of specific bioactivity and mass recovery. Copyright © 2014 John Wiley & Sons, Ltd.     

高效疏水相互作用色谱法复性与同时纯化重组人Flt3配体的包涵体蛋白质

Flt3配体(FL)是一类具有促进早期造血功能的细胞因子,在促进造血细胞生长发育及造血动员方面具有重要的临床应用价值。为了用基因工程方法获得大量用于临床和研究的重组人FL(rhFL)蛋白质,本文对在大肠杆菌(E. coli)中表达得到的Flt3配体的包涵体进行回收、洗涤,溶解于8 mol/L脲后在高效疏水相互作用色谱(HPHIC)柱上进行rhFL包涵体的复性与同时纯化,并对其保留特征和复性规律进行了研究。结果表明,在连续进样、变性蛋白质质量浓度为8.51 g/L、固定相选用端基为PEG800、流动相添加4 mol/L脲、1.8 mmol/L 还原型谷胱甘肽(GSH)和0.3 mmol/L氧化型谷胱甘肽(GSSH)、pH 7.0的优化条件下,复性与同时纯化rhFL包涵体的质量回收率为36.9%,纯度达94.5%以上。本文仅用一步HPHIC法成功地复性与同时纯化了rhFL蛋白质,为获得高活性的rhFL产品奠定了一定的工作基础。     

Refolding of urea‐denatured α‐chymotrypsin by protein‐folding liquid chromatography

An approach for re‐folding denatured proteins during proteome research by protein folding liquid chromatography (PFLC) is presented. Standard protein, α‐chymotrypsin (α‐Chy), was selected as a model protein and hydrophobic interaction chromatography was performed as a typical PFLC; the three different α‐Chy states – urea‐denatured (U state), its folded intermediates (M state) and nature state (N state) – were studied during protein folding. Based on the test by matrix‐assisted laser desorption/ionization time of flight mass spectrometry and bioactivity, only one stable M state of the α‐Chy was identified and then it was prepared for further investigation. The specific bioactivity of the refolded α‐Chy was found to be higher than that of commercial α‐Chy as the urea concentration in the sample solution ranged from 1.0 to 3.0 m ; the highest specific bioactivity at urea concentration was 1.0 m , indicating the possibility for re‐folding some proteins that have partially or completely lost their bioactivity, as a dilute urea solution was employed for dissolving the sample. The experiment showed that the peak height of its M state increased with increasing urea concentration, and correspondingly decreased in the amount of the refolded α‐Chy. When the urea concentration reached 6.0 m , the unfolded α‐Chy could not be refolded at all. Copyright © 2012 John Wiley & Sons, Ltd.     

采用不同疏水相互作用色谱柱从包涵体中快速制备重组人干细胞因子

为了提高重组人干细胞因子(rhSCF)的复性效率,改进了高效疏水相互作用色谱(HPHIC)纯化和复性rhSCF的方法。首先将目标蛋白溶解于8.0 mol/L脲中,然后将rhSCF包涵体的提取液直接进样到不同规格的HPHIC柱进行纯化和复性。优化了固定相配基结构和流动相组成等实验条件,结果表明,本方法可以快速地获得高质量回收率和高生物活性的rhSCF,rhSCF在40 min内即可完成复性与纯化,目标蛋白的纯度在95.5%以上,质量回收率高于49.6%。通过体积排阻色谱和基质辅助激光解吸离子化飞行时间质谱(MALDI-TOF-MS)的分析,确认rhSCF以单体存在。结果进一步证明HPHIC法是同时复性和纯化重组蛋白的有效工具。     

Refolding and purification of rhNTA protein by chromatography

RhNTA protein is a new thrombolytic agent which has potential medicinal and commercial value. Protein refolding is a bottleneck for large‐scale production of valuable proteins expressed as inclusion bodies in Escherichia coli. The denatured rhNTA protein was refolded by an improved size‐exclusion chromatography refolding process achieved by combining an increasing arginine gradient and a decreasing urea gradient (two gradients) with a size‐exclusion chromatography refolding system. The refolding of denatured rhNTA protein showed that this method could significantly increase the activity recovery of protein at high protein concentration. The activity recovery of 37% was obtained from the initial rhNTA protein concentration up to 20 mg/mL. After refolding by two‐gradient size‐exclusion chromatography refolding processes, the refolded rhNTA was purified by ion‐exchange and affinity chromatography. The purified rhNTA protein showed one band in SDS‐PAGE and the specific activity of purified rhNTA protein was 110,000 U/mg. Copyright © 2008 John Wiley & Sons, Ltd.     

重组人干扰素-γ的制备与鉴定

用聚乙二醇200疏水相互作用色谱固定相(PEG200-STHIC)分别在色谱柱和色谱饼上完成了一步复性并同时纯化来源于大肠杆菌(E.coli)表达的重组人干扰素-γ(rhIFN-γ)。为了能使色谱分离方法用于不同来源的rhIFN-γ的纯化,对rhIFN-γ在反相色谱、离子交换色谱、固定化镍离子亲和色谱上的保留行为也进行了研究。色谱柱纯化的rhIFN-γ收集液经排阻色谱除盐和冷冻干燥得到rhIFN-γ干粉。用基质辅助激光解吸电离飞行时间质谱对rhIFN-γ干粉进行了测定,rhIFN-γ单体的相对分子质量为17184.0,二聚体的相对分子质量为34204.4。用细胞病变抑制法(CPEI)测定rhIFN-γ干粉的比活性为9.5×108 IU/mg。用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）测定rhIFN-γ干粉的纯度高于95%。用色谱柱复性并同时纯化rhIFN-γ的质量回收率达到93.7%,纯度高于95%,比活性为4.3×107 IU/mg。结果表明,采用PEG200-STHIC色谱柱复性并同时纯化rhIFN-γ是一种十分高效的方法。     

蛋白折叠液相色谱法复性和纯化大肠杆菌表达的重组人粒细胞集落刺激因子

用蛋白折叠液相色谱法(PFLC)对大肠杆菌表达的包涵体形式的重组人粒细胞集落刺激因子(rhG-CSF)进行了复性并同时纯化。用Cu2+-亚氨基二乙酸（IDA） Sepharose作为固定化金属离子亲和色谱的固定相。在低浓度脲存在下,以咪唑为洗脱剂,采用线性梯度洗脱rhG-CSF。该法仅通过一步PFLC分离,减少了复性过程中rhG-CSF的聚集,复性后的rhG-CSF的比活性为1.8×108 IU/mg,纯度为97%,质量回收率为32%。     

Isolation and purification of recombinant human plasminogen Kringle 5 by liquid chromatography and ammonium sulfate salting‐out

In this work, a novel method was established to isolate and purify Human plasminogen Kringle 5 (HPK5) as a histidine‐tagged fusion protein expressed in Escherichia coli BL21 (DE3). This method consisted of sample extraction using a Ni‐chelated Sepharose Fast‐Flow affinity column, ammonium sulfate salting‐out and Sephadex G‐75 size‐exclusion column in turn. The purity analysis by SDS–PAGE, high‐performance size‐exclusion and reversed‐phase chromatographies showed that the obtained recombinant fusion HPK5 was homogeneous and its purity was higher than 96%; the activity analysis by chorioallantoic membrane model of chicken embryos revealed that the purified recombinant HPK5 exhibited an obvious anti‐angiogenic activity under the effective range of 5.0–25.0 µg/mL. Through this procedure, about 19 mg purified recombinant fusion HPK5 can be obtained from 1 L of original fermentation solution. Approximate 32% of the total recombinant fusion HPK5 can be captured and the total yield was approximately 11%. Copyright © 2013 John Wiley & Sons, Ltd.     

Refolding human lysozyme produced as an inclusion body by urea concentration and pH gradient ion exchange chromatography

Summary A new dual-gradient ion exchange chromatographic method was developed to improve the refolding yield of human lysozyme produced inEscherichia coli as an inclusion body. The dissolved and stretched polypeptide chain in a concentrated non-ionic denaturant was adsorbed onto an ion exchange column and induced to refold by gradually decreasing the denaturant concentration and increasing pH in the flowing buffer. The dual gradients of denaturant concentration and pH provided a gradual change of the solution environment along the chromatographic column for the protein to refold, resulting in enhanced activity yield and purity. A post-separation was also studied using size-exclusion chromatography to remove protein aggregates and mis-folded proteins after the refolding step.     

An efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment,separation, and purification of alkaloids and organic Acids from natural products

This study presents an efficient strategy based on liquid‐liquid extraction and pH‐zone‐refining counter‐current chromatography for selective enrichment, separation, and purification of alkaloids and organic acids from natural products. First, an acid or base modified two‐phase solvent system with maximum or minimum partition coefficient was developed for the liquid‐liquid extraction of the crude extract. As a result, alkaloids or organic acids could be selectively enriched in the upper or lower phase. Then pH‐zone‐refining counter‐current chromatography was employed to separate and purify the selectively enriched alkaloids or organic acids efficiently. The selective enrichment and separation of five bufadienolide from toad venom of Bufo marinus was used as an example to show the advantage of this strategy. As a result, 759 mg of selectively enriched bufadienolide was obtained from 2 g of crude extract and the total content of five targets was increased from 14.64 to 83%. A total of 31 mg of marinobufagin‐3‐adipoyl‐l ‐arginine, 42 mg of telocinobufagin‐3‐pimeloyl‐l ‐arginine, 51 mg of telocinobufagin‐3‐suberoyl‐l ‐arginine, 132 mg of marinobufagin‐3‐suberoyl‐l ‐arginine, and 57 mg of bufalin‐3‐suberoyl‐l ‐arginine were all simultaneously separated from 500 mg of selectively enriched sample, with the purity of 92.4, 97.5, 90.3, 92.1, and 92.8%, respectively.     

Temperature‐controlled liquid–liquid microextraction combined with high‐performance liquid chromatography for the simultaneous determination of diazinon and fenitrothion in water and fruit juice samples

A simple, environmentally benign, and rapid method based on temperature‐controlled liquid–liquid microextraction using a deep eutectic solvent was developed for the simultaneous extraction/preconcentration of diazinon and fenitrothion. The method involved the addition of deep eutectic solvent to the aqueous sample followed by heating the mixture in a 75°C water bath until the solvent was completely dissolved in the aqueous phase. Then, the resultant solution was cooled in an ice bath and a cloudy solution was formed. Afterward, the mixture was centrifuged and the enriched deep eutectic solvent phase was analyzed by high‐performance liquid chromatography with ultraviolet detection for quantification of the analytes. The factors affecting the extraction efficiency were optimized. Under the optimized extraction conditions, the limits of detection for diazinon and fenitrothion were 0.3 and 0.15 μg/L, respectively. The calibration curves for diazinon and fenitrothion exhibited linearity in the concentration range of 1–100 and 0.5–100 μg/L, respectively. The relative standard deviations for five replicate measurements at 10.0 μg/L level of analytes were less than 2.8 and 4.5% for intra‐ and interday assays, respectively. The developed method was successfully applied to the determination of diazinon and fenitrothion in water and fruit juice samples.     

Isolation and purification of alkaloids from lotus leaves by ionic‐liquid‐modified high‐speed countercurrent chromatography

An effective high‐speed countercurrent chromatography method was successfully established by using ionic liquids as the modifier of the two‐phase solvent system. Adding a small amount of ionic liquids significantly shortens the separation time and improves the separation efficiency. The conditions of ionic‐liquid‐modified high‐speed countercurrent chromatography including solvent systems, types and content of added ionic liquids, and ionic liquids posttreatment were investigated. The established method was successfully applied to separate alkaloids from lotus leaves using a two‐phase solvent system composed of petroleum ether/ethyl acetate/methanol/water/[C₄mim][BF₄] (1:5:1:5:0.15, v/v/v/v/v). Four alkaloids pronuciferine (1.7 mg), N‐nornuciferine (4.3 mg), nuciferine (3.1 mg), and roemerine (2.1 mg) were obtained with the purities of 90.53, 92.25, 99.86, and 98.63%, respectively, from 100 mg crude extract of lotus leaves. The results indicated that the ionic‐liquid‐modified high‐speed countercurrent chromatography method was suitable for alkaloid separation from lotus leaves and would be a promising method for the separation of alkaloids from other natural products.     

Isolation and purification of alkaloids from the fruits of Macleaya cordata by ionic‐liquid‐modified high‐speed counter‐current chromatography

Macleaya cordata (Willd) R. Br. is a medicinal plant. The most important bioactive compounds of M. cordata are alkaloids that have many biological activities including antifungal, anti‐inflammatory, and antitumor. In this study, an ionic‐liquid‐modified high‐speed counter‐current chromatography method was established to obtain alkaloids from the fruits of M. cordata. The conditions of ionic‐liquid‐modified high‐speed counter‐current chromatography, including solvent systems, the content of ionic liquid (1‐butyl‐3‐methylimidazolium tetrafluoroborate [C₄mim][BF₄]), and the posttreatment of the ionic liquid, were investigated. Five alkaloids protopine, allocryptopine, sanguinarine, 8‐O‐demethylchelerythrine, and chelerythrine were separated from the extract of the fruits using a high speed counter‐current chromatography with two‐phase solvent system composed of dichloromethane/methanol/0.3 mol/L hydrochloric acid aqueous solution/[C₄mim][BF₄] (4:2:2:0.015, v/v). Their purities were 96.33, 95.56, 97.94, 96.22, and 97.90%, respectively. The results indicated that a small amount of ionic liquids as modifier of the two‐phase solvent system could shorten the separation time and improve the separation efficiency of the alkaloids from the fruits. The ionic‐liquid‐modified high‐speed counter‐current chromatography would provide a feasible way for highly effective separation of alkaloids from natural products.     

反相高效液相色谱-脉冲电化学检测法测定重组人生长激素中异丙基-β-D-硫代半乳糖苷

采用反相高效液相色谱（RP-HPLC）-脉冲电化学检测（PED）法测定了重组人生长激素（rhGH）中的诱导剂异丙基-β-D-硫代半乳糖苷（IPTG）。rhGH样品经超滤离心后,用超纯水提取,经C18色谱柱分离,用脉冲电化学器检测。结果表明,样品中添加0.02~0.10 mg/L的IPTG,其回收率为100%~102%,相对标准偏差（n=3）小于10%。在优化的条件下,IPTG的检出限可达1 μg/L（0.1 pmol,25 μL）。该方法简便高效,具有良好的灵敏度、回收率和重复性。     

Solubilization and Refolding with Simultaneous Purification of Recombinant Human Stem Cell Factor

Recombinant human stem cell factor (rhSCF) was solubilized and renatured from inclusion bodies expressed in Escherichia coli. The effect of both pH and urea on the solubilization of rhSCF inclusion bodies was investigated; the results indicate that the solubilization of rhSCF inclusion bodies was significantly influenced by the pH of the solution employed, and low concentration of urea can drastically improve the solubilization of rhSCF when solubilized by high pH solution. The solubilized rhSCF can be easily refolded with simultaneous purification by ion exchange chromatography (IEC), with a specific activity of 7.8 × 10⁵ IU·mg⁻¹, a purity of 96.3%, and a mass recovery of 43.0%. The presented experimental results show that rhSCF solubilized by high pH solution containing low concentration of urea is easier to be renatured than that solubilized by high concentration of urea, and the IEC refolding method was more efficient than dilution refolding and dialysis refolding for rhSCF. It may have a great potential for large-scale production of rhSCF.     

New liquid‐crystalline thermosets from liquid‐crystalline bisazomethynic epoxy resins with naphthylene disruptors in the central core

We synthesized novel epoxy‐terminated monomers on the basis of imine groups with spacers of different lengths between mesogens and reactive groups and examined their mesogenic properties. Their reaction with primary aromatic diamines and tertiary amines was carried out to investigate the formation of liquid‐crystalline thermosets. We explored how the curing conditions and the structures of the monomers and amines affected the formation of ordered networks. The special symmetry of a 1,5‐disubstituted naphthalene unit in the central core led to nematic mesophases in the pure liquid‐crystalline epoxy resins, and thermosets with locked nematic textures were obtained in all cases, regardless of the length of the spacer. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1536–1544, 2003     

Dimeric liquid‐crystalline epoxyimine monomers: Influence of dipolar moments on mesomorphic behavior and the formation of liquid‐crystalline thermosets

We examine some of the structural aspects that influence the mesomorphic behavior of liquid‐crystalline dimeric epoxy resins with imine groups in the mesogens. We synthesized two new series of monomers and compared them with previously synthesized monomers. Compared with previously studied series, the imine group in the new monomers is oriented differently with respect to the ether and ester groups linked to the end of the mesogenic unit. Our results confirmed the importance of polarization of the mesogenic groups and the presence of an ester group in the inner position in the formation of smectic mesophases. By curing with primary and tertiary amines, we demonstrate that these two requirements are necessary if liquid‐crystalline thermosets are to be obtained with different degrees of order. These studies were carried out with differential scanning calorimetry, polarized optical microscopy, and X‐ray diffraction. © 2003 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 41: 1465–1477, 2003     

Simple and rapid determination of zaltoprofen in human plasma by manual‐shaking‐assisted dispersive liquid–liquid microextraction followed by liquid chromatography with ultraviolet detection

A readily applicable method was developed to determine the concentration level of zaltoprofen, a non‐steroidal antiinflammatory drug from the propionic acid family, in human plasma. This method is based on manual‐shaking‐assisted dispersive liquid–liquid microextraction coupled with liquid chromatography with ultraviolet detection. Factors affecting the extraction efficiency were screened and optimized by experimental design using fractional factorial and central composite designs, respectively. Optimal conditions were: 220 μL of C₂H₄Cl₂ (extraction solvent), 5 mL of 3.75% w/v NaCl aqueous solution at pH 2.0, and manual shaking for 13 s (65 times). The resulting extraction method yielded a reasonable enrichment factor of 18.0 (±0.6, n  = 3) and extraction recovery of 86.0% (±3.3%, n  = 3). The established method was validated for selectivity, linearity, precision, accuracy, matrix effect, recovery, dilution integrity, and stability, and it met the acceptable criteria for all of the tested parameters. Specifically, the method was linear in the range of 0.16–50.0 mg/L, precise (< 8.8% RSD), accurate (–7.5–5.6% deviation), and showed negligible matrix effects (96.1–106.4%) with high absolute recovery (94.5–97.7%). Compared with previous methods involving labor‐intensive liquid–liquid extraction or non‐specific protein precipitation, our method allows the simple, rapid, and efficient determination of zaltoprofen using the most affordable analytical instrument, liquid chromatography with ultraviolet detection.     

Isolation and purification of six iridoid glycosides from gardenia jasminoides fruit by medium‐pressure liquid chromatography combined with macroporous resin chromatography

Gardeniae fructus is one of the most frequently used herbs in traditional Chinese medicine. In the present study, a process for the enrichment of six iridoid glycosides from Gardeniae fructus was developed using medium‐pressure liquid chromatography combined with macroporous resin and reversed‐phase chromatography. The purities of different fractions from Gardeniae fructus were assessed using quantitative high‐performance liquid chromatography. After fractionation using HPD‐100 column chromatography, a 30% ethanol fraction was selected based on high‐performance liquid chromatography and liquid chromatography with mass spectrometry qualitative analysis to separate and purify. Based on the orientation analysis results, six compounds—deacetyl asperulosidic acid methyl ester, gardenoside, ixoroside, scandoside methyl ester, genipin‐1‐O‐β‐d‐ gentiobioside, and geniposide—were successfully isolated and purified in three to four combined steps from Gardeniae fructus. The purities of these compounds were found by high‐performance liquid chromatography analysis to be 97.9, 98.1, 95.5, 96.3, 97.1, and 98.7%, respectively. Moreover, their structures were elucidated by NMR spectroscopy and liquid chromatography with tandem mass spectrometry. The separation process was highly efficient, rapid, and accurate, making it a potential approach for the large‐scale production of iridoids in the laboratory and providing several marker compounds for quality control. This procedure may be meaningful for the purification of other natural products used in traditional Chinese medicine.