Protein purification: an overview

A Review on Bacteriocin Extraction Techniques from Lactic Acid Bacteria

Lactic acid bacteria (LAB) are widely known for the production of secondary metabolites such as organic acids and other bioactive compounds such as bacteriocins. Finding a broad application in food and healthcare, bacteriocins have received increased attention due to their inherent antimicrobial properties. However, the extraction of bacteriocins is often plagued with low yields due to the complexity of the extraction processes and the diversity of bacteriocins themselves. Here, we review the current knowledge related to bacteriocin extraction on the different extraction techniques for isolating bacteriocins from LAB. The advantages and disadvantages of each technique will also be critically appraised, taking into account factors such as extraction efficiency, scalability and cost-effectiveness. This review aims to guide researchers and professionals in selecting the most suitable approach for bacteriocin extraction from LAB by illuminating the respective advantages and limitations of various extraction techniques.

Surface imprinted microhelical magnetic polymer nanocomposite fibers for targeted lysozyme separation

Magnetic microhelical structures have recently drawn attention as microswimmers capable of mimicking bacterial propulsion in the low Reynolds number regime. Such structures can be used in microfluidic bioseparation or targeted delivery and their interaction with proteins is extremely important. In this study we fabricated silica coated magnetic microhelices resembling artificial bacterial flagella like structures via electrospinning magnetite nanoparticle incorporated polystyrene nanocomposite solution followed by silica sol coating. Two model proteins, Lysozyme (Lyz) and Bovine Serum Albumin (BSA), were used for protein imprinting along with a polydopamine layer on the magnetic microhelical substrates. The adsorption mechanism of lysozyme on the molecularly imprinted support system was analyzed using adsorption model fitting (Langmuir, Freundlich and Temkin). Adsorption capacity, selective binding and imprinting factor values were calculated for both imprinted (Lyz and BSA) and non-imprinted samples. A significantly higher adsorption capacity was obtained compared to previously reported studies.

Complete biosynthetic pathway of furochromones in Saposhnikovia divaricata and its evolutionary mechanism in Apiaceae plants

Furochromones are specific bioactive secondary metabolites of many Apiaceae plants. Their biosynthesis remains largely unexplored. In this work, we dissect the complete biosynthetic pathway of major furochromones in the medicinal plant Saposhnikovia divaricata by characterizing prenyltransferase, peucenin cyclase, methyltransferase, hydroxylase, and glycosyltransferases. De novo biosynthesis of prim-O-glucosylcimifugin and 5-O-methylvisamminoside is realized in Nicotiana benthamiana leaves. Through comparative genomic and transcriptomic analyses, we further find that proximal duplication and high expression of a pentaketide chromone synthase gene SdPCS, together with the presence of a lineage-specific peucenin cyclase gene SdPC, lead to the predominant accumulation of furochromones in the roots of S. divaricata among surveyed Apiaceae plants. This study paves the way for metabolic engineering production of furochromones, and sheds light into evolutionary mechanisms of furochromone biosynthesis among Apiaceae plants.

Application research and progress of microalgae as a novel protein resource in the future

Economic growth and health awareness spotlight opportunities and challenges in the food industry, particularly with decreasing arable land, climate change, dwindling freshwater resources, and pollution affecting traditional protein sources. Microalgae have emerged as a promising alternative, with higher protein content, better nutritional quality, and greater environmental resilience compared to conventional crops. They offer a protein balance comparable to meat, making them a sustainable protein source with health benefits like antioxidants, cardiovascular support, and anti-inflammatory properties. Improving the protein content of microalgae through optimized cultivation techniques is crucial to fully realize its potential as a novel food source. While there are already microalgae-based food products in the market, challenges remain in utilizing microalgal protein for widespread food production, emphasizing the need for further research. This review article explores the impact of microalgae culture conditions on protein content, the physicochemical and nutritional characteristics of microalgal protein, the health advantages of microalgal proteins and their derivatives, as well as research on separating and purifying microalgal proteins and their derivatives. It also delves into the current opportunities and obstacles of microalgal proteins and their derivatives as food, highlighting the potential for investigating the link between microalgal protein food and human health.

Magnetic silica-coated cutinase immobilized via ELPs biomimetic mineralization for efficient nano-PET degradation

The proliferation of nano-plastic particles (NPs) poses severe environmental hazards, urgently requiring effective biodegradation methods. Herein, a novel method was developed for degrading nano-PET (polyethylene terephthalate) using immobilized cutinases. Nano-PET particles were prepared using a straightforward method, and biocompatible elastin-like polypeptide-magnetic nanoparticles (ELPs-MNPs) were obtained as magnetic cores via biomimetic mineralization. Using one-pot synthesis with the cost-effective precursor tetraethoxysilane (TEOS), silica-coated magnetically immobilized ELPs-tagged cutinase (ET-C@SiO2@MNPs) were produced. ET-C@SiO2@MNPs showed rapid magnetic separation within 30 s, simplifying recovery and reuse. ET-C@SiO2@MNPs retained 86 % of their initial activity after 11 cycles and exhibited superior hydrolytic capabilities for nano-PET, producing 0.515 mM TPA after 2 h of hydrolysis, which was 96.6 % that of free enzymes. Leveraging ELPs biomimetic mineralization, this approach offers a sustainable and eco-friendly solution for PET-nanoplastic degradation, highlighting the potential of ET-C@SiO2@MNPs in effective nanoplastic waste management and contributing to environmental protection and sustainable development.

Efficient experimental method for purifying allergens from aqueous extracts

Studying the molecular and immunological basis of allergic diseases often requires purified native allergens. The methodologies for protein purification are usually difficult and may not be completely successful. The objective of this work was to describe a methodology to purify allergens from their natural source, while maintaining their native form. The purification strategy consists of a three-step protocol and was used for purifying five specific allergens, Ole e 1, Amb a 1, Alt a 1, Bet v 1 and Cup a 1. Total proteins were extracted in PBS (pH 7.2). Then, the target allergens were pre-purified and enriched by salting-out using increasing concentrations of ammonium sulfate. The allergens were further purified by anion exchange chromatography. Purification of Amb a 1 required an extra step of cation exchange chromatography. The detection of the allergens in the fractions obtained were screened by SDS-PAGE, and Western blot when needed. Further characterization of purified Amb a 1 was performed by mass spectrometry. Ole e 1, Alt a 1, Bet v 1 and Cup a 1 were obtained at > 90 % purity. Amb a 1 was obtained at > 85 % purity. Overall, we propose an easy-to-perform purification approach that allows obtaining highly pure allergens. Since it does not involve neither chaotropic nor organic reagents, we anticipate that the structural and biological functions of the purified molecule remain intact. This method provides a basis for native allergen purification that can be tailored according to specific needs.

Innovation in precision fermentation for food ingredients

A transformation in our food production system is being enabled by the convergence of advances in genome-based technologies and traditional fermentation. Science at the intersection of synthetic biology, fermentation, downstream processing for product recovery, and food science is needed to support technology development for the production of fermentation-derived food ingredients. The business and markets for fermentation-derived ingredients, including policy and regulations are discussed. A patent landscape of fermentation for the production of alternative proteins, lipids and carbohydrates for the food industry is provided. The science relating to strain engineering, fermentation, downstream processing, and food ingredient functionality that underpins developments in precision fermentation for the production of proteins, fats and oligosaccharides is examined. The production of sustainably-produced precision fermentation-derived ingredients and their introduction into the market require a transdisciplinary approach with multistakeholder engagement. Successful innovation in fermentation-derived ingredients will help feed the world more sustainably.

Novel melanin-derived stationary phase for immobilized metal ion affinity chromatography in recombinant His-tagged protein purification

The matrix of the stationary phase is a crucial element in affinity chromatography for protein purification. Various materials, including polymer or magnetic materials, have been employed as the matrix in the purification of His-tagged protein. Here, for the first time, we utilized a combination of melanin and alginate, both natural polymer materials, to synthesize Ni-melanin/alginate (Ni-M/A) beads for His-tagged protein purification. We investigated the binding of His-tagged Mpro on the Ni-M/A beads, referred to as Ni-M/A-Mpro, and assessed the elution efficiency of Mpro from the beads. Our examination involved FTIR, EDS, XRD, SDS-PAGE, and Western blotting methods. FTIR spectra revealed notable changes in the stretching patterns and intensities of hydroxyl, amine, carbonyl, imine and amide chemical groups, when Mpro protein was present in the Ni-M/A sample. XRD spectra demonstrated the occurrence of two Nickel peaks at 35-40 deg and 40-45 deg in Ni-M/A, but only one nickel peak at 35-40 deg in Ni-M/A-Mpro, indicating the binding of Mpro on the Nickel ions. EDS analysis reported a decrease in the concentration of Nickel on the surface of Ni-M/A from 16% to 7% when Mpro protein was loaded into the stationary phase. Importantly, our data indicated that the purity of the His-tagged protein Mpro after purification reached 97% after just one-step purification using the Ni-M/A stationary phase. Moreover, the binding capacity of Ni-M/A for Mpro was approximately 5.2 mg/g with recovery efficiency of 40%. Our results suggested Ni-M/A as a highly potential solid phase for affinity chromatography in the purification of His-tagged protein.

From Fundamental Amyloid Protein Self-Assembly to Development of Bioplastics

Proteins can self-assemble into a range of nanostructures as a result of molecular interactions. Amyloid nanofibrils, as one of them, were first discovered with regard to the relevance of neurodegenerative diseases but now have been exploited as building blocks to generate multiscale materials with designed functions for versatile applications. This review interconnects the mechanism of amyloid fibrillation, the current approaches to synthesizing amyloid protein-based materials, and the application in bioplastic development. We focus on the fundamental structures of self-assembled amyloid fibrils and how external factors can affect protein aggregation to optimize the process. Protein self-assembly is essentially the autonomous congregation of smaller protein units into larger, organized structures. Since the properties of the self-assembly can be manipulated by changing intrinsic factors and external conditions, protein self-assembly serves as an excellent building block for bioplastic development. Building on these principles, general processing methods and pathways from raw protein sources to mature state materials are proposed, providing a guide for the development of large-scale production. Additionally, this review discusses the diverse properties of protein-based amyloid nanofibrils and how they can be utilized as bioplastics. The economic feasibility of the protein bioplastics is also compared to conventional plastics in large-scale production scenarios, supporting their potential as sustainable bioplastics for future applications.

Protein Hydrolysate from Underutilized Legumes: Unleashing the Potential for Future Functional Foods

Proteins play a vital role in human development, growth, and overall health. Traditionally, animal-derived proteins were considered the primary source of dietary protein. However, in recent years, there has been a remarkable shift in dietary consumption patterns, with a growing preference for plant-based protein sources. This shift has resulted in a significant increase in the production of plant proteins in the food sector. Consequently, there has been a surge in research exploring various plant sources, particularly wild, and underutilized legumes such as Canavalia, Psophocarpus, Cajanus, Lablab, Phaseolus, and Vigna, due to their exceptional nutraceutical value. This review presents the latest insights into innovative approaches used to extract proteins from underutilized legumes. Furthermore, it highlights the purification of protein hydrolysate using Fast Protein Liquid Chromatography. This review also covers the characterization of purified peptides, including their molecular weight, amino acid composition, and the creation of three-dimensional models based on amino acid sequences. The potential of underutilized legume protein hydrolysates as functional ingredients in the food industry is a key focus of this review. By incorporating these protein sources into food production, we can foster sustainable and healthy practices while minimizing environmental impact. The investigation of underutilized legumes offers exciting possibilities for future research and development in this area, further enhancing the utilization of plant-based protein sources.

Technological interventions in improving the functionality of proteins during processing of meat analogs

Meat analogs have opened a new horizon of opportunities for developing a sustainable alternative for meat and meat products. Proteins are an integral part of meat analogs and their functionalities have been extensively studied to mimic meat-like appearance and texture. Proteins have a vital role in imparting texture, nutritive value, and organoleptic attributes to meat analogs. Processing of suitable proteins from vegetable, mycoproteins, algal, and single-cell protein sources remains a challenge and several technological interventions ranging from the isolation of proteins to the processing of products are required. The present paper reviews and discusses in detail various proteins (soy proteins, wheat gluten, zein, algal proteins, mycoproteins, pulses, potato, oilseeds, pseudo-cereals, and grass) and their suitability for meat analog production. The review also discusses other associated aspects such as processing interventions that can be adapted to improve the functional and textural attributes of proteins in the processing of meat analogs (extrusion, spinning, Couette shear cell, additive manufacturing/3D printing, and freeze structuring). '.

Recombinant protein polymers as carriers of chemotherapeutic agents

Chemotherapy is the standard of care for the treatment of cancer and infectious diseases. However, its use is associated with severe toxicity and resistance arising mainly due to non-specificity, resulting in disease progression. The advancement in recombinant technology has led to the synthesis of genetically engineered protein polymers like Elastin-like polypeptide (ELP), Silk-like polypeptide (SLP), hybrid protein polymers with specific sequences to impart precisely controlled properties and to target proteins that have provided satisfactory preclinical outcomes. Such protein polymers have been exploited for the formulation and delivery of chemotherapeutics for biomedical applications. The use of such polymers has not only solved the limitation of conventional chemotherapy but has also improved the therapeutic index of typical drug delivery systems. This review, therefore, summarizes the development of such advanced recombinant protein polymers designed to deliver chemotherapeutics and also discusses the key challenges associated with their current usage and their application in the future.

Expression and purification of recombinant human CCL5 and its biological characterization

C-C motif chemokine ligand 5 (CCL5) is crucial in the tumor microenvironment. It has been previously reported to act as a key role in tumor invasion and metastasis. However, the function of exogenous CCL5 in ovarian cancer has not been well-characterized. The present study attempted to express and purify recombinant CCL5 protein and investigate the exogenous CCL5 in ovarian cancer cell proliferation. The human CCL5 was amplified and inserted into the pET-30a vectors for prokaryotic expression in Escherichia coli BL21. Soluble His-CCL5 was successfully expressed with 0.1 mmol/L of isopropyl-β-D-1-tiogalactopiranoside at 25 ℃ and purified by affinity chromatography. Additionally, methyl thiazolyl tetrazolium (MTT) assay demonstrated that CCL5 promotes ovarian cancer cell proliferation; increases the phosphorylation levels of extracellular-signal-regulated kinase and mitogen-activated protein kinase/ERK kinase, and increases the mRNA levels of Jun, NF-κB2, Nras, Relb, and Traf2. Furthermore, treatment with the MEK inhibitor reduced the Jun, NF-κB2, and Traf2 mRNA levels, indicating that exogenous CCL5 increased ovarian cancer cell proliferation, through MEK/ERK pathway activation, and Jun, NF-κB2, and Traf2 expression. The present study provided primary data for further studies to discover more CCL5 functions in ovarian cancer.

Aptamer loaded superparamagnetic beads for selective capturing and gentle release of activated protein C

Activated protein C (APC) is a serine protease with anticoagulant and cytoprotective activities which make it an attractive target for diagnostic and therapeutic applications. In this work, we present one-step activation of APC from a commercial source of protein C (PC, Ceprotin) followed by rapid and efficient purification using an APC-specific aptamer, HS02-52G, loaded on MyOne superparamagnetic beads. Due to the Ca2+-dependent binding of APC to HS02-52G, an efficient capturing of APC was applied in the presence of Ca2+ ions, while a gentle release of captured APC was achieved in the elution buffer containing low EDTA concentration (5 mM). The captured and eluted APC showed more than 95% purity according to SDS-PAGE gel analysis and an enzyme-linked fluorescent assay (VIDAS Protein C). The purification yield of 45% was calculated when 4.2 µg APC was used, however this yield reduced to 21% if the starting amount of APC increased to 28.5 µg. Altogether, this method is recommended for rapid and efficient PC activation and APC purification. The purified APC can be used directly for downstream processes where high concentration of pure and active APC is needed.

Design of Experiment (DoE) for Optimization of HPLC Conditions for the Simultaneous Fractionation of Seven α-Amylase/Trypsin Inhibitors from Wheat (Triticum aestivum L.)

Wheat alpha-amylase/trypsin inhibitors remain a subject of interest considering the latest findings showing their implication in wheat-related non-celiac sensitivity (NCWS). Understanding their functions in such a disorder is still unclear and for further study, the need for pure ATI molecules is one of the limiting problems. In this work, a simplified approach based on the successive fractionation of ATI extracts by reverse phase and ion exchange chromatography was developed. ATIs were first extracted from wheat flour using a combination of Tris buffer and chloroform/methanol methods. The separation of the extracts on a C18 column generated two main fractions of interest F1 and F2. The response surface methodology with the Doehlert design allowed optimizing the operating parameters of the strong anion exchange chromatography. Finally, the seven major wheat ATIs namely P01083, P17314, P16850, P01085, P16851, P16159, and P83207 were recovered with purity levels (according to the targeted LC-MS/MS analysis) of 98.2 ± 0.7; 98.1 ± 0.8; 97.9 ± 0.5; 95.1 ± 0.8; 98.3 ± 0.4; 96.9 ± 0.5, and 96.2 ± 0.4%, respectively. MALDI-TOF-MS analysis revealed single peaks in each of the pure fractions and the mass analysis yielded deviations of 0.4, 1.9, 0.1, 0.2, 0.2, 0.9, and 0.1% between the theoretical and the determined masses of P01083, P17314, P16850, P01085, P16851, P16159, and P83207, respectively. Overall, the study allowed establishing an efficient purification process of the most important wheat ATIs. This paves the way for further in-depth investigation of the ATIs to gain more knowledge related to their involvement in NCWS disease and to allow the absolute quantification in wheat samples.

In Vitro Biochemical Analysis of Recombinant Plant Proteins Under Oxidation

Biochemical analysis is crucial for determining protein functionality changes during various conditions, including oxidative stress conditions. In this chapter, after giving brief guidelines for experimental design, we provide step-by-step instructions to purify recombinant plant proteins from E. coli, to prepare reduced and oxidized proteins for activity assay, and to characterize the protein under reducing and oxidizing conditions, with a focus on thiol-based oxidative modifications, like S-sulfenylation and disulfide formations.

A Comprehensive Updated Review on Magnetic Nanoparticles in Diagnostics

Magnetic nanoparticles (MNPs) have been studied for diagnostic purposes for decades. Their high surface-to-volume ratio, dispersibility, ability to interact with various molecules and superparamagnetic properties are at the core of what makes MNPs so promising. They have been applied in a multitude of areas in medicine, particularly Magnetic Resonance Imaging (MRI). Iron oxide nanoparticles (IONPs) are the most well-accepted based on their excellent superparamagnetic properties and low toxicity. Nevertheless, IONPs are facing many challenges that make their entry into the market difficult. To overcome these challenges, research has focused on developing MNPs with better safety profiles and enhanced magnetic properties. One particularly important strategy includes doping MNPs (particularly IONPs) with other metallic elements, such as cobalt (Co) and manganese (Mn), to reduce the iron (Fe) content released into the body resulting in the creation of multimodal nanoparticles with unique properties. Another approach includes the development of MNPs using other metals besides Fe, that possess great magnetic or other imaging properties. The future of this field seems to be the production of MNPs which can be used as multipurpose platforms that can combine different uses of MRI or different imaging techniques to design more effective and complete diagnostic tests.

Evaluation of the influence of temperature on the protein-tannic acid complex

Precipitation of blood products from plasma fractionation has played a fundamental role in the industrial purification of important therapeutic products. Only a few studies have been reported by using tannins as proteins precipitant agent from whole plasma while, several conditions have been analyzed. Here, we decided to verify the effect of the temperature on the precipitation process of plasma proteins using tannic acid (TA). Plasma proteins were precipitated with tannic acid by using different temperature incubations. Subsequently, the protein-TA complex was analyzed by SDS-PAGE and quantified. In addition, the protein activity of the complex was measured after heating, as well as the structural changes of the complexes were accompanied by thermogravimetric analysis, differential scanning calorimetry and circular dichroism. In all conditions tested, tannic acid was able to precipitate without selectively separating the proteins in the mixture by using different temperatures during the precipitation process. Furthermore, the protein concentration from the plasma precipitate was not affected by different temperatures and the plasma precipitate was able to dissolve fibrin clots in vitro.

Proteomic Analysisof Food Allergens by MALDI TOF/TOF Mass Spectrometry

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) is largely recognized as an important tool in the analysis of many biomolecules such as proteins and peptides. The MS analysis of digested peptides to identify a protein or some of its modifications is a key step in proteomics. MALDI-MS is well suited for the peptide mass fingerprinting (PMF) technique, as well as selected fragmentation of various precursors using collisional-induced dissociation (CID) or post-source decay (PSD).In the last few years, MALDI-MS has played a significant role in food chemistry, especially in the detection of food adulterations, characterization of food allergens, and investigation of protein structural modifications induced by various industrial processes that could be an issue in terms of food quality and safety.Here, we present simple extraction protocols of allergenic proteins in food commodities such as milk, egg, hazelnut , and lupin seeds. Classic bottom-up approaches based on Sodium Dodecyl Sulphate (SDS) gel electrophoresis separation followed by in-gel digestion or direct in-solution digestion of whole samples are described. MALDI-MS and MS /MS analyses are discussed along with a comparison of data obtained by using the most widespread matrices for proteomic studies, namely, α-cyano-4-hydroxy-cinnamic acid (CHCA) and α-cyano-4-chloro-cinnamic acid (CClCA). The choice of the most suitable MALDI matrix is fundamental for high-throughput screening of putative food allergens.

Opportunities and challenges of the tag-assisted protein purification techniques: Applications in the pharmaceutical industry

Tag-assisted protein purification is a method of choice for both academic researches and large-scale industrial demands. Application of the purification tags in the protein production process can help to save time and cost, but the design and application of tagged fusion proteins are challenging. An appropriate tagging strategy must provide sufficient expression yield and high purity for the final protein products while preserving their native structure and function. Thanks to the recent advances in the bioinformatics and emergence of high-throughput techniques (e.g. SEREX), many new tags are introduced to the market. A variety of interfering and non-interfering tags have currently broadened their application scope beyond the traditional use as a simple purification tool. They can take part in many biochemical and analytical features and act as solubility and protein expression enhancers, probe tracker for online visualization, detectors of post-translational modifications, and carrier-driven tags. Given the variability and growing number of the purification tags, here we reviewed the protein- and peptide-structured purification tags used in the affinity, ion-exchange, reverse phase, and immobilized metal ion affinity chromatographies. We highlighted the demand for purification tags in the pharmaceutical industry and discussed the impact of self-cleavable tags, aggregating tags, and nanotechnology on both the column-based and column-free purification techniques.

Synthesis and Evaluation of Dye-Ligand Affinity Adsorbents for Protein Purification

Dye-ligand affinity chromatography is a widely used technique in protein purification. The utility of the reactive dyes as affinity ligands results from their unique chemistry, which confers wide specificity toward a large number of proteins. They are commercially available, inexpensive, stable and can easily be immobilized. Significant factors that contribute to the successful operation of a dye-ligand chromatography include matrix type, dye-ligand density, adsorption along with elution conditions and flow rate. The present chapter provides protocols for the synthesis of dye-ligand affinity adsorbents as well as protocols for screening, selection, and optimization of a given dye-ligand purification step. The purification of the glutathione transferases from Phaseolus vulgaris on Cibacron Blue 3GA-Sepharose affinity adsorbent is given as an example.

Expression, purification, and characterization of pneumococcal PsaA-PspA fusion protein

Streptococcus pneumoniae is a gram-positive bacterial pathogen causing invasive pneumonia, meningitis, otitis media, and bacteremia. Owing to the current pitfalls of polysaccharide and polysaccharide-conjugate vaccines, protein vaccines are considered promising candidates against pneumonia. Pneumococcal surface protein A (PspA) and pneumococcal surface adhesin A (PsaA) are virulence proteins showing good immunogenicity and protective effects against S. pneumoniae strains in mice. In this study, we expressed the fusion protein PsaA-PspA, which consists of PsaA and the N-terminal region of PspA family 1 and 2, in Escherichia coli. We describe a novel and effective method to purify PsaA-PspA using hydroxyapatite and two-step chromatography. After determining the optimal induction conditions and a series of purification steps, we obtained PsaA-PspA fusion protein with over 95% purity at a final yield of 22.44% from the starting cell lysate. The molecular weight of PsaA-PspA was approximately 83.6 kDa and its secondary structure was evaluated by circular dichroism. Immunization with the purified protein induced high levels of IgG antibodies in mice. Collectively, these results demonstrate that our purification method can effectively produce high-purity PsaA-PspA fusion protein with biological activity and chemical integrity, which can be widely applied to the purification of other PspA subclass proteins.

Reduce, Reuse and Recycle in Protein Chromatography: Development of an Affinity Adsorbent from Waste Paper and Its Application for the Purification of Proteases from Fish By-Products

In the present study, we report the development of a cellulose-based affinity adsorbent and its application for the purification of proteases from fish by-products. The affinity adsorbent was synthesized using cellulose microfibers as the matrix, isolated from recycled newspapers using the acid precipitation method. As an affinity ligand, the triazine dye Cibacron Blue 3GA (CB3GA) was used and immobilized directly onto the cellulose microfibers. Absorption equilibrium studies and frontal affinity chromatography were employed to evaluate the chromatographic performance of the adsorbent using as model proteins bovine serum albumin (BSA) and lysozyme (LYS). Absorption equilibrium studies suggest that the adsorption of both proteins obeys the Langmuir isotherm model. The kinetics of adsorption obey the pseudo-second-order model. The affinity adsorbent was applied for the development of a purification procedure for proteases from Sparus aurata by-products (stomach and pancreas). A single-step purification protocol for trypsin and chymotrypsin was developed and optimized. The protocol afforded enzymes with high yields suitable for technical and industrial purposes.

A Brief Reminder of Systems of Production and Chromatography-Based Recovery of Recombinant Protein Biopharmaceuticals

Recombinant proteins are produced for various applications in laboratory and industrial settings. Among them, therapeutic applications have evolved into a mature field in recent years, affecting the face of contemporary medical treatment. This, in turn, has stimulated an ever-greater need for innovative technologies for the description, expression, and purification of recombinant protein biopharmaceuticals. Therefore, many biopharmaceuticals are synthesized in heterologous systems to obtain satisfactory yields that cannot be provided by natural sources. As more than 35 years has passed since the first recombinant biopharmaceutical (human insulin) successfully completed clinical trials in humans, we provide a brief review of the available prokaryotic and eukaryotic expression systems, listing the advantages and disadvantages of their use. Some examples of therapeutic proteins expressed in heterologous hosts are also provided. Moreover, technologies for the universal extraction of protein molecules are mentioned here, as is the methodology of their purification.

Accelerated pharmaceutical protein development with integrated cell free expression, purification, and bioconjugation

The use of living cells for the synthesis of pharmaceutical proteins, though state-of-the-art, is hindered by its lengthy process comprising of many steps that may affect the protein’s stability and activity. We aimed to integrate protein expression, purification, and bioconjugation in small volumes coupled with cell free protein synthesis for the target protein, ciliary neurotrophic factor. Split-intein mediated capture by use of capture peptides onto a solid surface was efficient at 89–93%. Proof-of-principle of light triggered release was compared to affinity chromatography (His₆ fusion tag coupled with Ni-NTA). The latter was more efficient, but more time consuming. Light triggered release was clearly demonstrated. Moreover, we transferred biotin from the capture peptide to the target protein without further purification steps. Finally, the target protein was released in a buffer-volume and composition of our choice, omitting the need for protein concentration or changing the buffer. Split-intein mediated capture, protein trans splicing followed by light triggered release, and bioconjugation for proteins synthesized in cell free systems might be performed in an integrated workflow resulting in the fast production of the target protein.

Structure-based design and application of a nucleotide coenzyme mimetic ligand: Application to the affinity purification of nucleotide dependent enzymes

In the present study, a structure-based approach was exploited for the in silico design of a nucleotide coenzyme mimetic ligand. The enzyme formate dehydrogenase (FDH) was employed as a model in our study. The biomimetic ligand was designed and synthesized based on a tryptamine/3-aminopropylphosphonic acid bi-substituted 1,3,5-triazine (Trz) scaffold (Tra-Trz-3APP), which potentially mimics the interactions of NAD⁺-FDH complex. Molecular docking studies of the biomimetic ligand predicted that it can occupy the same binding site as the natural coenzyme. Molecular modeling and dynamics simulations revealed that the ligand binds in an energetically more stable pose in the FDH binding site, as it adopts a more twisty conformation, compared to the natural coenzyme. Study of the FDH/Tra-Trz-3APP-Sepharose interaction, through adsorption equilibrium studies and site-directed mutagenesis of selected FDH coenzyme binding residues, provided additional experimental evidences of the specificity of the interaction. The Tra-Trz-3APP-Sepharose biomimetic adsorbent was further evaluated towards a range of different dehydrogenases and was exploited for the development of a single-step purification protocol for FDH. The protocol afforded enzyme with high yield and purity, suitable for analytical and industrial purposes.

Kinetics of Antibody Aggregation at Neutral pH and Ambient Temperatures Triggered by Temporal Exposure to Acid

The purification process of an antibody in manufacturing involves temporal exposure of the molecules to low pH followed by neutralization-pH-shift stress-which causes aggregation. It remains unclear how aggregation triggered by pH-shift stress grows at neutral pH and how it depends on the temperature in an ambient range. We used static and dynamic light scattering to monitor the time-dependent evolution of the aggregate size of the pH-shift stressed antibody between 4.0 and 40.0 °C. A power-law relationship between the effective molecular weight and the effective hydrodynamic radius was found, indicating that the aggregates were fractal with a dimension of 1.98. We found that the aggregation kinetics in the lower-temperature range, 4.0-25.0 °C, were well described by the Smoluchowski aggregation equation. The temperature dependence of the effective aggregation rate constant gave 13 ± 1 kcal/mol of endothermic activation energy. Temporal acid exposure creates an enriched population of unfolded protein molecules that are competent of aggregating. Therefore, the energetically unfavorable unfolding step is not required and the aggregation proceeds faster. These findings provide a basis for predicting the growth of aggregates during storage under practical, ambient conditions.

Comparison of capillary electrophoresis and capillary liquid chromatography coupled to mass spectrometry for the analysis of transthyretin in human serum

Capillary electrophoresis and capillary liquid chromatography coupled to mass spectrometry (CE-MS and CapLC-MS, respectively) are nowadays very suitable techniques for the separation and characterization of intact proteins in biological fluids. In this paper, we compare the performance of both techniques for the analysis of transthyretin (TTR), which is a homotetrameric protein (relative molecular mass (Mr) ∼56,000) involved in different types of amyloidosis. Furthermore, it is also presented a novel sample pretreatment based on immunoprecipitation (IP) using Protein A Ultrarapid Agarose™ (UAPA) magnetic beads (MBs) to purify TTR from serum samples. This novel IP based on MBs allowed the detection of TTR monomeric proteoforms that were not possible to analyze by conventional IP in solution. In addition, UAPA MBs provided many other desirable advantages including higher selectivity and minimal unspecific binding of other proteins. CE-MS and CapLC-MS were applied to analyze serum samples from healthy controls and familial amyloidotic polyneuropathy type I (FAP-I) patients, who suffered from the most common hereditary systemic amyloidosis. Both techniques allowed detecting the same TTR proteoforms, including the mutant TTR (Met 30) variant (variation in relative molecular mass (ΔMr) was +32.07, from wild-type TTR). Migration/retention times and relative quantitation of the different proteoforms were similar and reproducible in both cases, but the limits of detection (LODs) achieved by CE-MS were slightly lower (2-2.5-fold). Some other differences were also found on separation selectivity (migration orders and separation of antibody), peak efficiency, total analysis time, calibration ranges and experimental Mr accuracy.