Method For Purification Of Proteins Research Articles

CONSTRUCTION, EXPRESSION AND PURIFICATION OF BRUCELLA SPP. RECOMBINANT PROTEINS L7/L12 AND SODC IN E. COLI

Brucellosis is still an important public health problem as long as natural reservoirs of infection exist. Currently, live attenuated vaccines based on strains S19, RB51 and Rev1 are used for the prevention of brucellosis in animals, the main disadvantage of which is virulence for humans. However, animal immunization programs should be implemented to reduce the incidence of humans. The development of safe and effective new generation vaccines using “omix” technology is a promising direction of vaccinology. A number of immunogenic Brucella proteins that elicit both a humoral and cellular immune response has been identified. The aim of these research was to optimize the expression and purification conditions of the Brucella spp. recombinant proteins L7/L12 and SodC. As a result, expressing plasmids pET/Br-L7/L12 and pET/Br-SodC were obtained. The parameters of target genes expression in E. coli were established and the method for purification of recombinant proteins was optimized. Purification of the L7/L12 protein was performed under hybrid conditions on HisPur agarose using a binding buffer containing 6 M guanidine hydrochloride, a wash buffer with 20 mM imidazole and an elution buffer with 300 mM imidazole. Protein SodC was purified under denaturing conditions with the addition of 1 % Triton X-100 and 1 % sodium deoxycholate to the lysis buffer. Inclusions were solubilized with a buffer containing 8 M urea and 5 mM imidazole. The target protein was eluted from HisPur agarose with buffer containing 8 M urea and 100 mM imidazole. The use of modified purification protocols made it possible to obtain purified recombinant proteins with a yield of 13 mg/L for the L7/L12 protein and 10 mg/L for the protein SodC, respectively. The specificity of the proteins was confirmed by a Western blot. Immunization of mice with recombinant proteins led to the production of specific antibodies, the titer of which in ELISA was 1:20480 and 1:20480, respectively.

A simple and rapid protein purification method based on cell-surface display of SUMO-fused recombinant protein and Ulp1 protease

The development of novel methods for highly efficient protein purification remains a research focus in the biotechnology field because conventional purification approaches, including affinity purification, gel filtration, and ion-exchange chromatography, require complex manipulation steps and are costly. Here, we describe a simple and rapid protein purification strategy in which the SUMO tag and Ulp1 protease are surface-displayed separately on Escherichia coli cells. After protein induction, the cells are harvested, resuspended in cleavage buffer, and incubated together for cleavage. In this approach, the surface-displayed Ulp1 cleaves the membrane-anchored SUMO fusion protein, resulting in the release of the target protein from the C-terminal of SUMO into the solution. The bacterial cells harboring SUMO and Ulp1 on their surfaces can be easily removed by centrifugation. To evaluate the purification method, we used red fluorescent protein (mCherry). Purified mCherry protein (7.72 ± 1.05 mg from 1 L of bacterial culture) was obtained after only 30 min of incubation. The protein purity was higher than 80%, and could be further improved (> 90%) by simple ultrafiltration. This study offers a promising and simple strategy for the purification of recombinant protein in its native form that requires only cleavage and centrifugation steps.

Optimizing Protein Function for Screening of Novel Inhibitors that Target Multi‐Drug Resistance in Cancers

P‐glycoprotein (P‐gp) belongs to the ATP‐Binding Cassette (ABC) transporter family of proteins and is strongly linked with multidrug resistance (MDR) in tumors where overexpression often abolishes the effects of chemotherapeutics by removing the therapeutics from the cells. In hopes of creating co‐therapeutics to re‐sensitize tumors to chemotherapeutics, we previously used high‐throughput in silico ligand docking studies and identified drug‐like compounds that reversed MDR in human cancer cells in culture. To evaluate the mechanism of inhibition in human P‐gp, we have isolated human P‐gp from the yeast Pichia pastoris using mixed detergent micelles. In order to effectively assess the potential inhibitors, we must be able to sufficiently stimulate our protein and have a high enough activity to see the inhibitory effects of the potential inhibitors. In previous work, we found that the activity of P‐gp assembled into membrane nanodiscs had significantly higher basal activity in the absence of transport substrate than P‐gp in detergent micelles. However, significant increase in activity in the presence of the substrate verapamil was not observed in micelles or nanodiscs. Here, we report methods of protein purification and nanodisc assembly modified to have optimally functional human P‐gp. The resulting purified P‐gp will be used to evaluate the inhibition mechanism of lead compounds that were shown to reverse MDR in cancer cell culture.Support or Funding InformationThis work was supported by NIH NIGMS [R15GM094771‐02] to PDV and JGW, SMU Hamilton Undergraduate Research Scholars and Undergraduate Research Assistantship Programs, the SMU Center for Drug Discovery, Design and Delivery, the Communities Foundation of Texas, and private gifts from Ms. Suzy Ruff of Dallas, Texas, and Ms. Myra Williams, Ph.D. of Naples, Florida. The authors would like to thank Dr. Ina L. Urbatsch, Texas Tech University Health Science Center, for providing the P. pastoris cells expressing the human wild‐type MDR1 used in this work.

Cyclodextrin and its derivatives enhance protein crystallization by grafted on crystallization plates

Protein drugs are attracting increasing attention. Eight of best-selling drugs in worldwide are proteins. Crystallization is an important protein purification method; however, it remains a bottleneck step. Heterogeneous nucleate is an effective method of enhancing protein crystallization. Cyclodextrin has been widely used in pharmaceutics, and our previous study showed that it is an effective heterogeneous nucleate for enhancing protein crystallization, and it may be widely used in purification of protein drugs. However, cyclodextrin must be added into the crystallization plate wells by hand, which is labor intensive and is not beneficial to automated crystallization screening. We grafted β-cyclodextrin (β-CD) and its derivatives (i.e., p-toluenesulfonyl-β-cyclodextrin [PTCD], mono-(6-(1,6-hexamethylenediamine)-6-deoxy)-β-cyclodextrin [MHCD] and mercapto-β-cyclodextrin [MCD]) on crystallization plates and tested their effects on protein crystallization. Protein crystallization success rate was improved, particularly for the PTCD-grafted group. This is an easy method to facilitate protein crystallization and can be widely applied for automatic crystallization screening.

Development and characterization of standard reagents for cell-based prepandemic influenza vaccine products

ABSTRACT Outbreaks of infection by novel avian influenza virus strains in humans cause public health issues worldwide, and the development of vaccines against such novel strains is the most effective method for the prevention of these virus outbreaks. All types of vaccines must be tested for potency before use; thus, quantitative potency assays are needed for influenza vaccines. The single radial immunodiffusion (SRID) assay is considered the gold standard for quantification of influenza virus antigens, and the SRID reference reagents are essential for the determination of vaccine potency. However, it remains debatable whether reference reagents derived from egg-based vaccine platforms can be used to precisely quantify non-egg-derived vaccines; thus, influenza vaccine production using cell-based platforms has attracted increasing attention. To evaluate the utility of reference reagents derived from a cell-based influenza vaccine platform, we prepared cell-based reference reagents from MDCK cell-grown viruses and compared them with egg-derived reference reagents. A primary liquid standard (PLS) was purified from cell-derived candidate influenza vaccine viruses, and hemagglutinin (HA) antigen content was determined by a densitometric method. The produced PLS could be stored at 4°C for more than 10 months. We also established a simple HA protein purification method for goat antiserum preparation, and the performance of the resulting antiserum was compared to that of standard reagents obtained using different production platforms. The results of this study indicate that these reference reagents can be used for both cell-based and egg-based production platforms and that the differences between these two types of platforms are negligible.

Comparison of the pH-dependent formation of His and Cys heptapeptide complexes of nickel(II), copper(II), and zinc(II) as determined by ion mobility-mass spectrometry.

The analog methanobactin (amb) peptide with the sequence ac-His1 -Cys2 -Gly3 -Pro4 -Tyr5 -His6 -Cys7 (amb5A ) will bind the metal ions of zinc, nickel, and copper. To further understand how amb5A binds these metals, we have undertaken a series of studies of structurally related heptapeptides where one or two of the potential His or Cys binding sites have been replaced by Gly, or the C-terminus has been blocked by amidation. The studies were designed to compare how these metals bind to these sequences in different pH solutions of pH 4.2 to 10 and utilized native electrospray ionization (ESI) with ion mobility-mass spectrometry (IM-MS) which allows for the quantitative analysis of the charged species produced during the reactions. The native ESI conditions were chosen to conserve as much of the solution-phase behavior of the amb peptides as possible and an analysis of how the IM-MS results compare with the expected solution-phase behavior is discussed. The oligopeptides studied here have applications for tag-based protein purification methods, as therapeutics for diseases caused by elevated metal ion levels or as inhibitors for metal-protein enzymes such as matrix metalloproteinases.

A simplified protein purification method through nickel cleavage of the recombinant protein from the Escherichia coli cell surface.

To simplify the protein purification process, we developed a novel one-step purification method in which the recombinant protein can be cleaved directly from the Escherichia coli cell surface. This method involves fusion of the target protein to the C-terminus of a LOS tag comprising a surface anchor protein (Lpp-OmpA) and a sequence-specific nickel-assisted cleavage (SNAC)-tag. The LOS tag facilitates the anchoring of the target protein to the outer membrane of E. coli cells and its separation from the cell membrane through Ni2+ cleavage. Intact, biologically active protein with a purity of 95% and a yield of approximately 100 mg per liter of culture can be readily obtained through Ni2+ cleavage in resuspension solution followed by centrifugation. In this study, a practical and promising protein purification method has been established with minimal labor and cost, as no cell disruption and chromatographic separation are required downstream.

A simple method for non-denaturing purification of biotin-tagged proteins through competitive elution with free biotin.

The use of avidin or streptavidin in the purification of biotinylated proteins has been highly restricted due to the harsh and denaturing elution conditions. Here, we use biotinylated bovine serum albumin as a working model to demonstrate a simple and rapid method for biotin-tagged protein purification under non-denaturing conditions. The biotinylated bovine serum albumin is specifically bound to the anti-biotin antibody agarose beads and competitively eluted with free biotin under near-neutral conditions. The optimized elution conditions include using 4 mg/ml biotin (pH 8.5) as the elution buffer and allowing the buffer to incubate with agarose beads for 30min prior to elution. The elution recovery rate is over 85% without apparent protein denaturation. The method is applicable for both immunoprecipitation and column chromatography.

Classification of Cutibacterium acnes at phylotype level by MALDI-MS proteotyping.

Cutibacterium acnes is a major commensal human skin bacteria. It is a producer of propionic acids that maintain skin acidic pH to inhibit the growth of pathogens. On the other hand, it is also associated with diseases such as acne vulgaris and sarcoidosis. C. acnes strains have been classified into six phylotypes using DNA-based approaches. Because several characteristic features of C. acnes vary according to the phylotype, the development of a practical method to identify these phylotypes is needed. For rapid identification of phylotypes for C. acnes strains, a matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) fingerprinting technique has been applied; however, some phylotypes have not been discriminated. We developed a high-throughput protein purification method to detect biomarker proteins by ultrafiltration. MALDI-MS proteotyping using profiling of identified biomarker peaks was applied for the classification of 24 strains of C. acnes, and these were successfully classified into the correct phylotypes. This is a promising method that allows the discrimination of C. acnes phylotypes independent of a DNA-based approach.

BioID Combined with Mass Spectrometry to Study Herpesvirus Protein-Protein Interaction Networks.

Herpes viruses are important human pathogens that cause a wide range of diseases from skin lesions to malignancies. Protein interactions drive many cellular events and mediate a number of biochemical pathways leading to different physiological outcomes. Protein interactions between viral proteins and host proteins play significant roles in viral entry, replication and suppression of host-immune responses. Therefore, the study of virus-host interactions promises significant advancement in designing therapeutics to control infection and disease. Various approaches are employed in the field to study and identify protein interactions that combine affinity purification along with different detection methods. Advancements in protein purification and high-throughput detection methods have resulted in an unprecedented level of discovery. Here we detail the use of proximity dependent biotinylation (BioID) as a means of affinity purification coupled with the use of LC-MS/MS for the detection and identification of protein-protein interaction networks.

Cellulose Nanofibrous Membranes Modified with Phenyl Glycidyl Ether for Efficient Adsorption of Bovine Serum Albumin

Hydrophobic interaction chromatography (HIC) as an indispensable method for protein purification has attracted considerable attentions of researchers as well as biopharmaceutical industries. However, the low binding capacity and slow adsorption rate of the currently available HIC media lead to a little supply and high price of the highly purified proteins. Herein, nanofibrous membranes with hydrophobic binding sites were developed for HIC by directly coupling phenyl glycidyl ether on the hydrolyzed cellulose acetate nanofiber membrane (cellulose-phenyl NFM). Scanning electron microscope (SEM), water contact angle (WCA), Fourier transform infrared (FTIR), thermogravimetric analysis (TGA), Brunauer–Emmett–Teller (BET) surface area analysis and capillary flow porometer (CFP) were applied to evaluate the physically and chemically structural transformation. The obtained cellulose-phenyl NFMs showed a proper hydrophilcity (WCA = 37°), a relatively high BET surface area (3.6 times the surface area of commercial fibrous membranes), and tortuous-channel structure with through-hole size in the range of 0.25–1.2 μm, which led to a little non-specificity adsorption, high bovine serum albumin adsorption capacity of 118 mg g−1, fast adsorption process within 12 h, good long-term stability and reusability. Moreover, compared with traditional modification methods which always include activation and graft two steps, direct coupling method is more efficient for HIC media fabrication. Therefore, cellulose-phenyl NFMs with outstanding protein adsorption performance could be a kind of promising candidate for HIC.

An efficient and rapid method to extract and purify protein – Liquid Triphasic Flotation system

Microalgae are rich in valuable biomolecules and grow on non-arable land with rapid growth rate, which has a host of new possibility as alternative protein sources. In the present study, extraction of proteins from Chlorella vulgaris via an efficient technique, Liquid Triphasic Flotation (LTF) system, was studied. The optimized conditions in LTF system were 70% v/v of t-butanol, 40% w/v of salt solution, 0.5% w/v of biomass, pH 5.54, 1:1 of salt to t-butanol solution, and 10 min of air flotation time to attain 87.23% of protein recovery and 56.72% of separation efficiency. Besides, the study on recycling t-butanol has demonstrated that only one run was sufficient to maintain the performance of system. The efficiency of LTF in extracting protein has performed better than just Three Phase Partitioning (TPP) system. LTF system is hence an effective protein extraction and purification method with minimum operation unit and processing time.

Nanoparticle-doped polystyrene/polyacrylonitrile nanofiber membrane with hierarchical structure as promising protein hydrophobic interaction chromatography media

Abstract Hydrophobic interaction chromatography (HIC) as an indispensable method for protein purification has attracted considerable attentions of researchers as well as biopharmaceutical industries. However, the operation pressure-drop and flow rate of the typical HIC porous resin beads are less than satisfactory. To address these issues, composite nanofibrous membranes (CNFMs) with controllable wettability have been developed by multi-component electrospinning of polystyrene/polyacrylonitrile (PS/PAN), and further by regulating the solution properties and introducing SiO 2 nanoparticles in, CNFMs with proper wettability and large surface area of 23.6 m−2 g−1 were fabricated. The obtained CNFMs showed a high static adsorption capacity of 78 mg g−1 and fast adsorption process within 30 min. Additionally, a high saturation dynamic binding capacity of 39.6 mg ml−1 was obtained under a low pressure-drop of 200 Pa, which surpassed the commercial HIC membrane media. Moreover, these membranes have a selectivity toward the protein with higher hydrophobicity , and proteins adsorbed on the membranes can be eluted with 10 wt% ethanol aqueous solution. Therefore, such a successful fabrication of nanofibrous membranes with outstanding hydrophobic protein adsorption performance could provide a promising platform to prepare economical and inspiring HIC media in the future.

Технология получения белкового концентрата овса посевного с высокими физико-химическими и функционально-технологическими характеристиками

The current intensive industrialization has changed the food preferences of consumers. As a result, there is a growing demand for high-grade high-nutritional meat and dairy products, which, in its turn, triggered an increase in the demand for grain crops and led to higher animal feed prices. All these affected the price and quality of the finished product, since farms are trying to stay profitable. As a consequence, the high cost of animal proteins make producers look for other sources of protein with similar qualities. Common oat (Avena sativa L.) remains the most cultivated species. Oats are a source of high-quality protein with an optimal amino acid balance. The paper features a oat protein technology (Avena sativa). The research defined the parameters of the protein extraction process. For acid and alkaline methods, the following optimum parameters were revealed: temperature – 40 ± 2°C, hydraulic module – 1:10, time – 90 minutes, active acidity of the acid extraction – 2.0 units, active acidity of alkaline extraction
 – 9.0 units. The authors managed to obtain protein substances with the molecular weight > 50 kDa. The optimal parameters of ultrafiltration of the protein extract were as follows: pore diameter = 100 kDa at pH 8.0 and 0.5 MPa. The ultrafiltration conducted under these conditions showed that the content of high molecular fractions (globulins and albumins) increased from 39.12% to 55.15% for the extract obtained by alkaline method, whereas the content of low molecular weight fractions (prolamins and glutelins) decreased from 60.88% to 44.85%. Ultrafiltration of protein extracts obtained by alkaline and acidic methods made it possible to concentrate protein fractions with a molecular weight ≥ 50 kDa. When a 10% aqueous solution of succinic acid was used as a precipitator, the protein precipitation degree equaled 89.3%. The paper introduces a new oat protein purification method. The optimal multiplicity of purification by RP-HPLC was 4 purification cycles. For the alkaline extract, the total content of high molecular weight fractions (50.0–120.0 kDa) was 72.7% and the total content of low molecular weight fractions (15.0–49.0 kDa) was 27.3%. For the acid extract, the total content of high molecular weight fractions was 72.9%, while the content of low molecular weight fractions was 27.1%. Oat proteins obtained by alkaline and acid extraction demonstrated a high foaming ability (148–177%) at pH = 6.0–9.0, as well as a good fat and water retention capacity. The oat proteins were found to have a high content of protein and essential amino acids similar to animal proteins. A comparative analysis showed that oat protein can act as an alternative substitute for animal proteins.

First comprehensive view on a magnetic separation based protein purification processes: From process development to cleaning validation of a GMP-ready magnetic separator.

Magnetic separation processes are known as integrated bioanalytical protein purification method since decades and are well described. However, use of magnetic separation processes in a regulated industrial production environment has been prevented by the lack of suitable process equipment and prejudice against the productivity of the process and its qualification for cleaning-in-place operation. With the aim of overcoming this prejudice, a comprehensive process development approach is presented, based on a GMP-compliant magnetic separator, including an optimization of the batch adsorption process, implementation into a technical-scale, and the development and validation of cleaning routines for the device. By the implementation of a two-step counter-current binding process, it was possible to raise the yields of the magnetic separation process even for very low concentrated targets in a vast surplus of competing proteins, like the hormone equine chorionic gonadotropin in serum, from 74% to over 95%. For the validation of the cleaning process, a direct surface swabbing method combined with a total organic carbon analysis was established for the determination of two model contaminants. The cleanability of the process equipment was proven for both model contaminants by reliably meeting the 10ppm criteria.

Multifunctional elastin-like polypeptide renders \u03b2-glucosidase enzyme phase transition and high stability

BackgroundIn the enzymatic conversion of biomass, it becomes an important issue to efficiently and cost-effectively degrade cellulose into fermentable glucose. β-Glucosidase (Bgluc), an essential member of cellulases, plays a critical role in cellulosic biomass degradation. The difficulty in improving the stability of Bgluc has been a bottleneck in the enzyme-dependent cellulose degradation. The traditional method of protein purification, however, leads to higher production cost and a decrease in activity. To simplify and efficiently purify Bgluc with modified special properties, Bgluc-tagged ELP and His with defined phase transitions was designed to facilitate the process.ResultsHere, a novel binary ELP and His tag was fused with Bgluc from termite Coptotermes formosanus to construct a Bgluc–linker–ELP–His recombinant fusion protein (BglucLEH). The recombinant plasmid Bgluc expressing a His tag (BglucH) was also constructed. The BglucLEH and BglucH were expressed in E. coli BL21 and purified using inverse transition cycling (ITC) or Ni-NTA resin. The optimum salt concentration for the ITC purification of BglucLEH was 0.5 M (NH4)2SO4 and the specific activity of BglucLEH purified by ITC was 75.5 U/mg for substrate p-NPG, which was slightly higher than that of BglucLEH purified by Ni-NTA (68.2 U/mg). The recovery rate and purification fold of BglucLEH purified by ITC and Ni-NTA were 77.8%, 79.1% and 12.60, 11.60, respectively. The results indicated that purification with ITC was superior to the traditional Ni-NTA. The Km of BglucLEH and BglucH for p-NPG was 5.27 and 5.73 mM, respectively. The Kcat/Km (14.79 S−1 mM−1) of BglucLEH was higher than that of BglucH (12.10 S−1 mM−1). The effects of ELP tag on the enzyme activity, secondary structure and protein stability were also studied. The results showed that ELP tag did not affect the secondary structure or enzyme activity of Bgluc. More importantly, ELP improved the protein stability in harsh conditions such as heating and exposure to denaturant.ConclusionThe Bgluc–linker–ELP–His system shows wide application prospect in maintaining the activity, efficient purification and improving the stability of Bgluc. These properties of BglucLEH make it an interesting tool to reduce cost, to improve the efficiency of biocatalyst and potentially to enhance the degradation of lignocellulosic biomass.

A novel protein purification strategy mediated by the combination of CipA and Ssp DnaB intein

Protein purification is an indispensable step in diverse fields of biological research or production process. Conventional purification methods including the affinity purification or the usage of self-aggregating tags suffered from many drawbacks such as the complicated steps, high cost and low efficiency. Moreover, the fusion tag usually had negative effects on the activity of the target protein. To address the above issues, here we propose a novel protein purification method which needs simple operation steps, and this method is mediated by the combination of CipA protein and a mini-intein (Synechocystis sp. PCC6803 DnaB, Ssp DnaB), depending on the assembly function of CipA and the self-cleavage function of Ssp DnaB. To realize the purification, CipA-DnaB-eGFP protein was expressed and assembled into protein crystalline inclusions (PCIs) in E. coli. Then, only cell lysis, cleavage and centrifugation steps were required to purify eGFP. Purified eGFP was in the supernatant with a purity of over 90%. The cleavage efficiency and the yield of eGFP reached 51.96% and 13.99 ± 0.88 mg/L fermentation broth, respectively. Furthermore, to broaden the application of this approach, three other proteins which were maltose binding protein (MBP), ketoisovalerate decarboxylase (Kivd) and alcohol dehydrogenase (AdhP) were purified with high cleavage efficiency. The purified Kivd and AdhP remained high specific activities. This work demonstrated an effective and convenient protein purification method.

Magnetically steerable Fe3O4@Ni2+-NTA-polystyrene nanoparticles for the immobilization and separation of his6-protein

We developed Ni2+-nitrilotriacetic acid (NTA) functionalized polystyrene (Ni2+-NTA-PS) nanoparticles encapsulated with magnetic Fe3O4 nanoparticles (Fe3O4@Ni2+-NTA-PS nanoparticles) via miniemulsion/solvent evaporation method for the affinity purification of his6-tag recombinant proteins. Fe3O4@Ni2+-NTA-PS nanoparticles have a high surface to volume ratio, which enhanced the protein immobilization efficiency through the specific interaction between his6-tag of protein and Ni2+-NTA end of the polymer. The potential of Fe3O4@Ni2+-NTA-PS nanoparticles is demonstrated by a direct comparison with commercially available Ni2+-NTA-magnetic beads in his6-protein immobilization and recovery. Furthermore, the practical application of Fe3O4@Ni2+-NTA-PS magnetic nanoparticles is illustrated in his6-protein separation from crude cell lysate.

Semiautomated Small-Scale Purification Method for High-Throughput Expression Analysis of Recombinant Proteins.

The expression analysis of recombinant proteins is a challenging step in any high-throughput protein production pipeline. Often multiple expression systems and a variety of expression construct designs are considered for the production of a protein of interest. There is a strong need to triage constructs rapidly and systematically. This chapter describes a semiautomated method for the simultaneous purification and characterization of proteins expressed from multiple samples of expression cultures from the E. coli, baculovirus expression vector system, and mammalian transient expression systems. This method assists in the selection of the most promising expression construct(s) or the most favorable expression condition(s) to move forward into large-scale protein production.

Cloning, Expression, and Purification of Recombinant Neisseria gonorrhoeae Proteins.

Modern DNA recombinant techniques and major advances in genetic engineering have resulted in the development of bacterial expression systems that guarantee an unlimited supply of valuable proteins that have potential clinical or industrial use, but which are often limited by their low natural availability. This chapter provides the reader with a general scheme to clone, express, and purify native histidine (His)-tagged proteins in the desired quantity and quality required for its intended use, and reviews the most important factors affecting the production of recombinant proteins in a soluble form. Alternative methods for purification of insoluble recombinant proteins under denaturing conditions are also discussed. An optimized protocol to successfully purify native Neisseria gonorrhoeae Adhesin Complex Protein (Ng-ACP; NGO1981) is used as a technical example for the processes, which could potentially be applied to any gonococcal recombinant protein of interest.