Dynamic Cooperative Glycan Assembly Blocks the Binding of Bacterial Lectins to Epithelial Cells

Analysis of the sensitization activity of Moringa oleifera leaves protein

The determination of allergenic proteins in Moringa oleifera leaves, which is the main components of immune activity, has enabled the development of a more effective method for evaluating the activity of extracted Moringa oleifera leaves protein. In this study, the extraction process of Moringa oleifera leaves protein was optimized based on a single factor experiment. The hemagglutination-related properties of Moringa oleifera leaves protein, such as (thermal, acid-base) stability, sugar binding specificity, ion binding characteristics, and hemolytic activity, were detected. The optimal combination of extraction process was: extraction time of 6 h, material-liquid ratio of 1:8, and ammonium sulfate saturation of 60%. The extraction rate of moringa leaf protein under this condition was 14.37 mg/g. The molecular weight of moringa leaf protein was analyzed by SDS-PAGE, and the molecular weight was mainly concentrated around 23 kDa~70 kDa, with the highest content of 35 kDa (major allergen). The study of the hemagglutination characteristics of Moringa oleifera leaves protein revealed that the protein exhibited high stability at temperatures below 60°C, with complete loss of activity occurring at temperatures above 110°C for 20 min. The effect of different pH conditions on the hemagglutination capacity of Moringa oleifera leaves protein was readily discernible. The hemagglutination activity of Moringa oleifera leaves protein was 104 in a pH value from 3.7 to 7.8, and the hemagglutination activity was completely lost at a pH value higher than 11.9. D(+) anhydrous glucose is the specific inhibitory sugar of Moringa oleifera leaves protein lectin. Moringa oleifera leaves protein exhibits hemolytic activity at a concentration of at least 20 mg/mL, and α-methyl-mannoside, galactoside, raffinose and Al3+ can inhibit the hemolysis of Moringa oleifera leaves protein. The present study identified the effects of different factors on the coagulation activity and hemolytic ability of Moringa oleifera leaves protein, thereby providing a theoretical basis for further purification and application of Moringa oleifera lectin. However, it should be noted that the results of the mixture have certain limitations, and further purification of lectin is needed to obtain more targeted research results.

Two-Helix Supramolecular Proteomimetic Binders Assembled via PNA-Assisted Disulfide Crosslinking

Peptidic motifs folded in a defined conformation are able to inhibit protein-protein interactions (PPIs) covering large interfaces and as such they are biomedical molecules of interest. Mimicry of such natural structures with synthetically tractable constructs often requires complex scaffolding and extensive optimization to preserve the fidelity of binding to the target. Here, we present a novel proteomimetic strategy based on a 2-helix binding motif that is brought together by hybridization of peptide nucleic acids (PNA) and stabilized by a rationally positioned intermolecular disulfide crosslink. Using a solid phase synthesis approach (SPPS), the building blocks are easily accessible and such supramolecular peptide-PNA helical hybrids could be further coiled using precise templated chemistry. The elaboration of the structural design afforded high affinity SARS CoV-2 RBD (receptor binding domain) binders without interference with the underlying peptide sequence, creating a basis for a new architecture of supramolecular proteomimetics.

Switchable DNA-Encoded Chemical Library: Interconversion between Double- and Single-Stranded DNA Formats

DNA-Encoded Chemical Library (DEL) has attracted substantial attention due to the infinite possibility for hit discovery in both pharmaceutical companies and academia. The encoding method is the initial step of DEL construction and one of the cornerstones of DEL applications. Classified by the DNA format, the existing DEL encoding strategies could be categorized into single-stranded DNA-based strategies and double-stranded DNA-based strategies. The two DEL formats have their unique advantages but are usually incompatible with each other. To address this issue, we proposed the concept of interconversion between double- and single-stranded DEL based on the "reversible covalent headpiece (RCHP)" design, which combined maximum robustness of synthesis with extraordinary flexibility of applications in distinct setups. Future opportunities in this field were also proposed to advance DEL technology to a comprehensive drug discovery platform.

Reversible Covalent Headpiece Enables Interconversion between Double- and Single-Stranded DNA-Encoded Chemical Libraries

The use of a proper encoding methodology is one of the most important aspects when practicing DEL technology. A "headpiece"-based double-stranded DEL encoding method is currently the most widely used for productive DEL. However, the robustness of double-stranded DEL construction conflicts with the versatility presented by single-stranded DEL applications. We here report a novel encoding method, which is based on a "reversible covalent headpiece (RCHP)". The RCHP allows reversible interconversion between double- and single-stranded DNA formats, providing an avenue to robust synthesis and allowing for the applications in distinct setups. We have validated the versatility of this encoding method with encoded self-assembled chemical library and DNA-encoded dynamic library technology. Notably, based on the RCHP-settled library construction, a unique "ternary covalent complex" mediating ligand isolation methodology against non-immobilized targets was developed.

Recent Advances on the Selection Methods of DNA-Encoded Libraries

DNA-encoded libraries (DEL) have come of age and become a major technology platform for ligand discovery in both academia and the pharmaceutical industry. Technological maturation in the past two decades and the recent explosive developments of DEL-compatible chemistries have greatly improved the chemical diversity of DELs and fueled its applications in drug discovery. A relatively less-covered aspect of DELs is the selection method. Typically, DEL selection is considered as a binding assay and the selection is conducted with purified protein targets immobilized on a matrix, and the binders are separated from the non-binding background via physical washes. However, the recent innovations in DEL selection methods have not only expanded the target scope of DELs, but also revealed the potential of the DEL technology as a powerful tool in exploring fundamental biology. In this Review, we first cover the "classic" DEL selection methods with purified proteins on solid phase, and then we discuss the strategies to realize DEL selections in solution phase. Finally, we focus on the emerging approaches for DELs to interrogate complex biological targets.

Efficient Buchwald-Hartwig-Migita Cross-Coupling for DNA Thioglycoconjugation

An efficient method for the thioglycoconjugation of iodinated oligonucleotides by Buchwald-Hartwig-Migita cross-coupling under mild conditions is reported. The method enables divergent synthesis of many different functionalized thioglycosylated ODNs in good yields, without affecting the integrity of the other A, C, and G nucleobases.