Gellan beads as a transparent media for protein immobilization and affinity capture

Advances in fermentative production, purification, characterization and applications of gellan gum

Multiple microbial exopolysaccharides have been reported in recent decade with their structural and functional features. Gellan gum (GG) is among these emerging biopolymers with versatile properties. Low production yield, high downstream cost, and abundant market demand have made GG a high cost material. Hence, an understanding on the various possibilities to develop cost-effective gellan gum bioprocess is desirable. This review focuses on details of upstream and downstream process of GG from an industrial perspective. It emphasizes on GG producing Sphingomonas spp., updates on biosynthesis, strain and media engineering, kinetic modeling, bioreactor design and scale-up considerations. Details of the downstream operations with possible modifications to make it cost-effective and environmentally sustainable have been discussed. The updated regulatory criteria for GG as a food ingredient and analytical tools required to validate the same have been briefly discussed. Derivatives of GG and their applications in various industrial segments have also been highlighted.

Improvement of low-acyl gellan gum on gelation and microstructural properties of protein hydrolysates from male gonad of scallop (Patinopecten yessoensis)

This study aimed to examine the gelation and microstructural properties of scallop male gonad hydrolysates (SMGHs) in the presence of low-acyl gellan gum (GG) at different mass ratios. The rheological results showed that both elastic modulus and thermal stability of SMGHs were significantly improved by the addition of GG. Meanwhile, the relaxation time T₂₃ was significantly reduced in SMGHs/GG by low-field nuclear magnetic resonance, indicating a strong interaction between SMGHs and GG. Fourier transform infrared spectroscopy indicated the blueshift of amide I and II peaks in SMGHs/GG further demonstrated the electrostatic interaction between SMGHs and GG. The network structure of SMGHs/GG binary complexes was more compact and the surface was smoother than that of SMGHs by cryo-scanning electron microscopy. Furthermore, increasing the content of GG in the SMGHs/GG binary complex significantly reinforced the gel strength and promoted the gelation process.

Recent developments in protein-ligand affinity mass spectrometry

This review provides an overview of direct and indirect technologies to screen protein–ligand interactions with mass spectrometry. These technologies have as a key feature the selection or affinity purification of ligands in mixtures prior to detection. Specific fields of interest for these technologies are metabolic profiling of bioactive metabolites, natural extract screening, and the screening of libraries for bioactives, such as parallel synthesis libraries and small combichem libraries. The review addresses the principles of each of the methods discussed, with a focus on developments in recent years, and the applicability of the methods to lead generation and development in drug discovery.

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Direct Dynamic Protein-Affinity Selection Mass-Spectrometry

A new methodology is described enabling the affinity screening of potential ligands towards the human estrogen receptor alpha ligand binding domain (ERα-LBD). In-solution incubation is performed of the analyte and the His-tagged ERα-LBD. The bound complex is immobilized on a nickel-loaded protein-affinity selection column, where after the unbound fraction is removed. The immobilized protein–ligand complex is exposed to a decreased pH value and an increased organic modifier concentration releasing the ligand for MS detection, and precipitating the proteins on a filter positioned between the affinity column and the mass spectrometer. The trapping column can be regenerated for reuse at least 70 times. The advantages of the methodology over existing methodologies are the absence of a pre-concentration as well as a chromatographic separation step, resulting in a significantly shorter analysis time compared to previously described procedures, and in addition, allowing the determination of solutes with unfavorable chromatographic properties. The overall analysis time now can be reduced about 250% to approximately 6 min. Replacing the filters after every measurement results in an intra-day standard deviation of 14.8% and an inter-day standard deviation of 21.3%.