Two-Dimensional Detergent Expansion Strategy for Membrane Protein Studies.

Detergents are the most frequently applied reagents in membrane protein (MP) studies. The limited diversity of one-head-one-tailed traditional detergents, however, is far from sufficient for structurally distinct MPs. Expansion of detergent repertoire has a continuous momentum. In line with the speculation that detergent pre-assembly exerts superiority, herein we report for the first time cross-conjugation of two series of monomeric detergents for constructing a two-dimensional library of dimeric detergents. Optimum detergents stood out with unique preferences in the systematic evaluation of individual MPs. Furthermore, unprecedented hybrid detergents 14M8G and 14M9G enabled high-quality EM study of transporter MsbA and NMR study of G protein-coupled receptor A2A AR, respectively. Given the abundance of cross-coupling chemistries, comprehensive diversity could be readily covered that would facilitate the finding of new detergents for the manipulation of thorny MPs and innovation of the functional and structural study in future.

Design and synthesis of novel dual-cyclic RGD peptides for αvß3 integrin targeting.

The specific binding of RGD cyclic peptide with integrin αvß3 attracts great research interest for tumor-targeting drug delivery. Herein, we designed and synthesized a series of dual-ring RGD-peptide derivatives as a drug carrier for αvß3 targeting. Three novel peptides showed excellent cell adhesion inhibition effect, in which, P3 exhibited 7-fold enhancement in IC50 compared with cyclo(RGDfK). Drug-loaded cytotoxicity experiment and imaging experiment indicated that such dual-cyclic RGD peptides have good tumor targeting effects. This work provides a new strategy for the design of novel RGD peptides.

Catalytically Cleavable Detergent for Membrane Protein Studies.

Throughout the in vitro studies of membrane proteins (MPs), proper detergents are essential for the preparation of stable aqueous samples. To date, universally applicable detergents have not yet been reported to accommodate the distinct requirements for the highly diversified MPs and at the different stages of MP manipulation. Detergent exchange often has to be performed. We report herein the catalytically cleavable detergents (CatCDs) that can be efficiently removed to facilitate a complete exchange. To this end, functional groups, like propargyl and allyl, are introduced as branched chains or built in the hydrophobic chain close to the hydrophilic head. The representative CatCDs can be used as usual detergents in the extraction and purification of MPs and later be removed upon the addition of catalytic palladium. Mediated by CatCD-1, reconstitution of a transporter protein MsbA into a series of detergents was achieved. The extension of these designs could facilitate the future optimization of other biophysics studies.

Structure-Activity Relationship Studies of Hydantoin-Cored Ligands for Smoothened Receptor.

An underside binding site was recently identified in the transmembrane domain of smoothened receptor (SMO). Herein, we report efforts in the exploration of new insights into the interactions between the ligand and SMO. The hydantoin core in the middle of the parent compound was found to be highly conservative in chirality, ring size, and substituents. On each benzene at two ends, a plethora of variations, particularly halogen substitutions, were introduced and investigated. Analysis of the structure-activity relationship revealed miscellaneous halogen effects. The ligands with double halogen substituents exhibit remarkably enhanced potency, providing promising candidates that potentially overcome the common drug resistance and useful heavy-atom labeled chemical tools for co-crystallization studies of SMO.

Glycoengineering and glycosite-specific labeling of serum IgGs from various species.

Chemoenzymatic glycoengineering of immunoglobulin G (IgG) catalyzed by Endo-S is a powerful approach to remodel the heterogeneous N-glycoforms of Fc domain with a homogeneous synthetic glycan structure for enhanced Fc receptor-mediated effector functions. The previous researches on the method development mainly focused on human or humanized IgGs with therapeutic potentials. Here, for the first time we report the extended application of this method on glycan-remodeling of serum IgGs from other species including rabbit, mouse, and goat. Harnessing an azido-tagged non-natural N-glycan substrate and successive click reaction, glycosite-specific fluorescent labeling of IgGs was enabled. This study provided a new avenue for glycoengineering and Fc-specific labeling of IgGs with minimized influence on antigen-binding domains, and this method was adaptive to thousands of commercial antibody reagents from various species with great application potentials.

Glycoconjugate probes containing a core-fucosylated N-glycan trisaccharide for fucose lectin identification and purification.

Glyco-PAMAM dendrimers and glyco-agarose beads bearing a core-fucosylated N-glycan trisaccharide GlcNAcß1,4(Fucα1,6)GlcNAc or a non-fucose disaccharide GlcNAcß1,4GlcNAc were successfully synthesized and characterized by monosaccharide analysis with HPAEC-PAD technique. These glycoconjugates as fucose lectin probes were applied in fucose-specific lectin detection and purification. The model fucose lectin AAL indicated binding activity with the FITC-labeled PAMAM carrying core-fucose trisaccharide. An affinity chromatography column stuffed with the agarose beads carrying core-fucosylated trisaccharide exhibited a good specificity in purification of AAL than non-fucose disaccharide agarose beads. These novel glycoconjugates bearing the precise and simplified core-fucose N-glycan structure provided a potential application for core-fucose-specific lectin discovery.

Atmospheric pressure liquefaction of dried distillers grains (DDG) and making polyurethane foams from liquefied DDG.

In this study, dried distillers grains (DDG) was liquefied in acidic conditions at atmospheric pressure, and polyurethane foams were subsequently prepared from the liquefied DDG. Liquefaction was examined over a range of conditions including liquefaction time of 1-3 h, temperature of 150-170 degrees C, sulfuric acid (as catalyst) concentration of 1.0-3.0 wt%, and liquefaction solvent (ethylene carbonate) to DDG ratio of 3:1-5:1. The bio-polyols in the liquefied DDG were rich in hydroxyl groups, which can react with methylene diphenyl diisocyanate (MDI) to form cross-linked polyurethane networks. The biodegradability of the prepared polyurethane foams was also evaluated. This study strives to broaden the application of DDG as a feedstock for bio-polyurethane preparation.