Size of Protein is a Major Factor that Affects Retention on Preparative IMAC Columns

Facile Synthesis of Aptamer-Functionalized Polydopamine-Coated Magnetic Graphene Oxide Nanocomposites for Highly Efficient Purification of His-Tagged Proteins

Recombinant proteins hold significant importance in numerous disciplines. As the demand for expressing and purifying these proteins grows, the scientific community is in dire need of a simple yet versatile methodology that can efficiently purify these proteins. Aptamers as synthetic nucleic acid-based ligands with high affinity have shown promise in this regard, as they can capture targets through molecular recognition. In this study, novel aptamer-functionalized polydopamine-coated magnetic graphene oxide nanocomposites were facilely prepared, achieving an impressive average aptamer coverage density (45 nmol/mg). These nanocomposites exhibited a uniform structure and robust magnetic responsiveness. The findings indicated that they possess several advantages, such as rapid adsorption, substantial capacity (171.4 mg/g), and excellent reusability. Notably, due to the inherent properties of nucleic acids, the immobilized aptamer-magnetic beads can be utilized repeatedly with high purification efficiency. Finally, the nanocomposites were further employed to purify His-tagged proteins from actual samples. Remarkably, they were able to selectively and efficiently isolate His-tagged retinoid X receptor alpha protein from complex Escherichia coli lysate. The purified His-tagged retinoid X receptor alpha protein was analyzed using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry. This confirmed the efficacy of developed nanocomposites, reinforcing their vast potential for purification of His-tagged recombinant proteins.

Overcoming the Solubility Problem in E. coli: Available Approaches for Recombinant Protein Production

Despite the importance of recombinant protein production in the academy and industrial fields, many issues concerning the expression of soluble and homogeneous products are still unsolved. Several strategies were developed to overcome these obstacles; however, at present, there is no magic bullet that can be applied for all cases. Indeed, several key expression parameters need to be evaluated for each protein. Among the different hosts for protein expression, Escherichia coli is by far the most widely used. In this chapter, we review many of the different tools employed to circumvent protein insolubility problems.

Database Study on the Expression and Purification of Membrane Proteins

Membrane proteins are crucial for biological processes, and many of them are important to drug targets. Understanding the three-dimensional structures of membrane proteins are essential to evaluate their bio function and drug design. High-purity membrane proteins are important for structural determination. Membrane proteins have low yields and are difficult to purify because they tend to aggregate. We summarized membrane protein expression systems, vectors, tags, and detergents, which have deposited in the Protein Data Bank (PDB) in recent four-and-a-half years. Escherichia coli is the most expression system for membrane proteins, and HEK293 cells are the most commonly cell lines for human membrane protein expression. The most frequently vectors are pFastBac1 for alpha-helical membrane proteins, pET28a for beta-barrel membrane proteins, and pTRC99a for monotopic membrane proteins. The most used tag for membrane proteins is the 6×His-tag. FLAG commonly used for alpha-helical membrane proteins, Strep and GST for beta-barrel and monotopic membrane proteins, respectively. The detergents and their concentrations used for alpha-helical, beta-barrel, and monotopic membrane proteins are different, and DDM is commonly used for membrane protein purification. It can guide the expression and purification of membrane proteins, thus contributing to their structure and bio function studying.