Renaturation of Recombinant Human Granulocyte Colony‐Stimulating Factor Produced fromEscherichia coliUsing Size Exclusion Chromatography

Rate of dilution and redox ratio influence the refolding efficiency of recombinant fungal dehydrogenases

Dehydrogenases from fungi are attracting attention as industrial biocatalysts due to their high activity and chiral selectivity. However, these enzymes form insoluble aggregates when overexpressed in E. coli, limiting their industrial application. In the present study, we report the systematic development of a refolding process for selected, industrially relevant fungal dehydrogenases, viz., formate dehydrogenase from Candida boidinii (CbFDH) and formate and alcohol dehydrogenases from Geotrichum candium (GcFDH and GcADH, respectively). We first employed a screen to evaluate the effects of different variables on refolding including the buffer system, additives, and rate of dilution. The extent of refolding was determined by enzyme assays, circular dichroism, and tryptophan fluorescence. Our results showed that glycerol and reducing environment are essential for refolding of these dehydrogenases. Further, slow dilution of solubilized protein over 16 h dramatically improved the recovery of refolded enzymes compared to rapid dilution. The importance of slow dilution was further confirmed in a 10-fold scaled-up refolding trial. Overall, we demonstrate a robust method for refolding of fungal dehydrogenases, thus improving their availability for various biocatalytic applications.

Efficient and easily scalable protein folding strong anion exchange chromatography for renaturation and simultaneous purification of recombinant human asparaginase from E. coli

Recombinant proteins are revolutionizing present day therapeutics. They are generally expressed as insoluble inclusion bodies in the E. coli and mis-folding, loss of protein, and high cost of down streaming are the hurdles in their recovery. For the first time, we are reporting the refolding with simultaneous purification of rhASP in E. coli using a single step utilizing protein folding-strong anion exchange chromatography (PF-SAX). The purification method is also standardized for optimal concentration of solution additives, pH, and mobile phase composition. The results showed purification of rhASP with anion exchange chromatography was effective. Phosphate buffer and slightly alkaline pH produced significant recovery yields and purity profiles. The effect of solution additives such as arginine, glycerol, TMAO, sorbitol, dextran, glutamate, and fructose on rhASP renaturation is also investigated. Significant results were achieved using arginine-TMAO combination in terms of purity, recovery yield and specific activity of 99%, 78%, and 210 IU/mg, respectively. The work concludes that PF-SAX refolding method is superior to other conventional methods and it can be applied to large scale purification of rhASP produced in E. coli. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 34:1036-1044, 2018.

Efficient single step chromatographic purification of recombinant human antithrombin (rhAT) from Saccharomyces cerevisiae

Antithrombin (AT) is a glycoprotein that inactivates the several physiological target enzymes of coagulation system. The effect of purification strategies plays a crucial role in getting maximum recovery of yield, purity and biological activity of recombinant human antithrombin (rhAT). In the present work, the task of purifying rhAT from Saccharomyces cerevisiae BY4741 has been carried out using two different approaches such as cross flow filtration (CFF) system and chromatography methods. In the first approach, the protein was concentrated and partially purified through CFF to achieve maximum recovery yield and purity of 87 and 94 %, respectively. In the second approach, purification involved a single step chromatography with various types of ion exchange and size exclusion resins to analyze the maximum rhAT recovery yield and purity. From the experimental results, it has been observed that the size exclusion chromatography (SEC) technique with Superose 12 matrix was suitable for the purification of rhAT and achieved the maximum recovery yield and purity of 51 and 97 %, respectively. Further, to acquire a high recovery yield and purity of rhAT, the effect of various chromatographic conditions such as mobile phase, mobile phase pH, flow rate, sample volume and sample concentration were also investigated. Under the optimal chromatographic conditions, rhAT was significantly recovered and purified in a single step with maximum recovery yield, purity and biological activity of 67, 99 % and 410 IU/L, respectively. Based on these investigations, it was concluded that SEC with Superose 12 matrix was a more suitable and a potential method for the purification of rhAT.

Improved Production and Characterization of Recombinant Human Granulocyte Colony Stimulating Factor from E. coli under Optimized Downstream Processes

This work reports the upstream and downstream process of recombinant human granulocyte colony stimulating factor (rhG-CSF) expressed in Escherichia coli BL21 (DE3)pLysS. The fed batch mode was selected for the maximum output of biomass (6.4g/L) and purified rhG-CSF (136mg/L) under suitable physicochemical environment. The downstream processing steps viz., recovery, solubilization, refolding and concentration were optimized in this study. The maximum rhG-CSF inclusion bodies recovery yield (97%) was accomplished with frequent homogenization and sonication procedure. An efficient solubilization (96%) of rhG-CSF inclusion bodies were observed with 8M urea at pH 9.5. Refolding efficiency studies showed maximum refolding ⩾86% and ⩾84% at 20°C and pH 9 respectively. The renatured protein solution was concentrated, clarified and partially purified (⩾95%) by the cross flow filtration technique. The concentrated protein was further purified by a single step size exclusion chromatography with ⩾98% purity. The characterization of purified rhG-CSF molecular mass as evidenced by SDS-PAGE, western blot and LC/MS analysis was shown to be 18.8kDa. The secondary structure of rhG-CSF was evaluated by the CD spectroscopic technique based on the helical structural components. The biological activity of the purified rhG-CSF showed a similar activity of cell proliferation with the standard rhG-CSF. Overall, the results demonstrate an optimized downstream process for obtaining high yields of biologically active rhG-CSF.

Simplified in vitro refolding and purification of recombinant human granulocyte colony stimulating factor using protein folding cation exchange chromatography

Protein folding-strong cation exchange chromatography (PF-SCX) has been employed for efficient refolding with simultaneous purification of recombinant human granulocyte colony stimulating factor (rhG-CSF). To acquire a soluble form of renatured and purified rhG-CSF, various chromatographic conditions, including the mobile phase composition and pH was evaluated. Additionally, the effects of additives such as urea, amino acids, polyols, sugars, oxidizing agents and their amalgamations were also investigated. Under the optimal conditions, rhG-CSF was efficaciously solubilized, refolded and simultaneously purified by SCX in a single step. The experimental results using ribose (2.0M) and arginine (0.6M) combination were found to be satisfactory with mass yield, purity and specific activity of 71%, ≥99% and 2.6×10(8)IU/mg respectively. Through this investigation, we concluded that the SCX refolding method was more efficient than conventional methods which has immense potential for the large-scale production of purified rhG-CSF.

Refolding and simultaneous purification of recombinant human proinsulin from inclusion bodies on protein-folding liquid-chromatography columns

Protein-folding liquid chromatography (PFLC) is an effective and scalable method for protein renaturation with simultaneous purification. However, it has been a challenge to fully refold inclusion bodies in a PFLC column. In this work, refolding with simultaneous purification of recombinant human proinsulin (rhPI) from inclusion bodies from Escherichia coli were investigated using the surface of stationary phases in immobilized metal ion affinity chromatography (IMAC) and high-performance size-exclusion chromatography (HPSEC). The results indicated that both the ligand structure on the surface of the stationary phase and the composition of the mobile phase (elution buffer) influenced refolding of rhPI. Under optimized chromatographic conditions, the mass recoveries of IMAC column and HPSEC column were 77.8 and 56.8% with purifies of 97.6 and 93.7%, respectively. These results also indicated that the IMAC column fails to refold rhPI, and the HPSEC column enables efficient refolding of rhPI with a low-urea gradient-elution method. The refolded rhPI was characterized by circular dichroism spectroscopy. The molecular weight of the converted human insulin was further confirmed with SDS-18% PAGE, Matrix-Assisted Laser Desorption/ Ionization Time of Flight Mass Spectrometry (MALDI-TOF-MS) and the biological activity assay by HP-RPLC.

Fast preparation of recombinant human stem cell factor from inclusion bodies using different hydrophobic interaction chromatographic columns

A method was developed to increase the recovery of recombinant human stem cell factor (rhSCF) from inclusion bodies using high performance hydrophobic interaction chromatography (HPHIC). The target protein was first solubilized in 8.0 mol/L urea solution, and was purified and refolded simultaneously by HPHIC with different chromatographic cakes. Experimental conditions, such as the ligand structures of stationary phase and the composition of mobile phase, were optimized. Under the optimal conditions, high mass recoveries and specific activities of rhSCF were acquired, the purities of rhSCF were above 95.5%, and the mass recoveries of rhSCF were above 49.6%. The final product was also verified as monomer by size exclusion chromatography and matrix assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS). These results provided further evidence that HPHIC is an effective tool in the refolding and purification of recombinant proteins.

High pH solubilization and chromatography-based renaturation and purification of recombinant human granulocyte colony-stimulating factor from inclusion bodies

Recombinant human granulocyte colony-stimulating factor (rhG-CSF) is a very efficient therapeutic protein drug which has been widely used in human clinics to treat cancer patients suffering from chemotherapy-induced neutropenia. In this study, rhG-CSF was solubilized from inclusion bodies by using a high-pH solution containing low concentration of urea. It was found that solubilization of the rhG-CSF inclusion bodies greatly depended on the buffer pH employed; alkalic pH significantly favored the solubilization. In addition, when small amount of urea was added to the solution at high pH, the solubilization was further enhanced. After solubilization, the rhG-CSF was renatured with simultaneous purification by using weak anion exchange, strong anion exchange, and hydrophobic interaction chromatography, separately. The results indicated that the rhG-CSF solubilized by the high-pH solution containing low concentration of urea had much higher mass recovery than the one solubilized by 8 M urea when using anyone of the three refolding methods employed in this work. In the case of weak anion exchange chromatography, the high pH solubilized rhG-CSF could get a mass recovery of 73%. The strategy of combining solubilization of inclusion bodies at high pH with refolding of protein using liquid chromatography may become a routine method for protein production from inclusion bodies.

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 x 10(5) IU x 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.

Expression, refolding, and purification of a truncated human Delta-like1, a ligand of Notch receptors

The Notch signaling pathway plays a pivotal role in proliferation, apoptosis, and cell fate specification in both embryonic and postnatal development, and is a potential therapeutic target for human diseases such as cancer. To express in Escherichia coli and purify soluble fragment of human Delta-like1 (hDll1), we cloned two extracellular fragments of hDll1 [hDll1 (127-225) and hDll1 (26-225)]. The hDll1 (127-225) fragment was successfully expressed in E. coli as a GST fusion protein (GST-hDll1). The GST-hDll1 protein, which was expressed as inclusion bodies after induction by IPTG, was refolded and purified simultaneously using affinity chromatography and size exclusion chromatography. The purified GST-hDll1 was of more than 95% purity, and had a molecular weight of 39kDa. Reporter assay showed that GST-hDll1 could activate a reporter gene that is dependent on Notch activation. Therefore, using the E. coli expression system and different chromatography systems, we successfully expressed, refolded, and purified a biologically active GST-hDll1, which might be potentially useful for therapy and studying the Notch pathway.

Protein folding liquid chromatography and its recent developments

The ultimate goal of proteomics is to identify biologically active proteins and to produce them using biotechnology tools such as bacterial hosts. However, proteins produced by Escherichia coli must be refolded to their native state. Protein folding liquid chromatography (PFLC) is a new method developed in recent years, and it is widely used in molecular biology and biotechnology. In this paper, the new method, PFLC is introduced and its recent development is reviewed. In addition the paper includes definitions, advantages, principles, applications for both laboratory and large scales, apparatus, and effecting factors of PFLC. In addition, the role of this method in the future is examined.

Renaturation with simultaneous purification of rhG-CSF fromEscherichia 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.