Synthetic polyubiquitinated α-Synuclein reveals important insights into the roles of the ubiquitin chain in regulating its pathophysiology

Ubiquitination regulates, via different modes of modifications, a variety of biological processes, and aberrations in the process have been implicated in the pathogenesis of several neurodegenerative diseases. However, our ability to dissect the pathophysiological relevance of the ubiquitination code has been hampered due to the lack of methods that allow site-specific introduction of ubiquitin (Ub) chains to a specific substrate. Here, we describe chemical and semisynthetic strategies for site-specific incorporation of K48-linked di- or tetra-Ub chains onto the side chain of Lys12 of α-Synuclein (α-Syn). These advances provided unique opportunities to elucidate the role of ubiquitination and Ub chain length in regulating α-Syn stability, aggregation, phosphorylation, and clearance. In addition, we investigated the cross-talk between phosphorylation and ubiquitination, the two most common α-Syn pathological modifications identified within Lewy bodies and Parkinson disease. Our results suggest that α-Syn functions under complex regulatory mechanisms involving cross-talk among different posttranslational modifications

Native Chemical Ligation at Glutamine

The desulfurization reaction introduced by Yan and Dawson as a postnative chemical ligation step greatly expanded the scope of ligation chemistry beyond Xaa-Cys (Xaa is any amino acid) by making ligation at Xaa-Phe, Xaa-Val, Xaa-Lys, Xaa-Leu, Xaa-Thr, and Xaa-Pro junctions accessible in the synthesis of functional proteins. A new ligation site based on Xaa-Gln utilizing γ-mercaptoglutamine is reported, and several examples on the efficiency of ligation coupled with desulfurization are provided

Nonclassical Crystal Growth of Supramolecular Polymers in Aqueous Medium

International audienceAbstract A mechanistic understanding of the principles governing the hierarchical organization of supramolecular polymers offers a paradigm for tailoring synthetic molecular architectures at the nano to micrometric scales. Herein, the unconventional crystal growth mechanism of a supramolecular polymer of superbenzene(coronene)‐diphenylalanine conjugate (Cr‐FF OEt ) is demonstrated. 3D electron diffraction (3D ED), a technique underexplored in supramolecular chemistry, is effectively utilized to gain a molecular‐level understanding of the gradual growth of the initially formed poorly crystalline hairy, fibril‐like supramolecular polymers into the ribbon‐like crystallites. The further evolution of these nanosized flat ribbons into microcrystals by oriented attachment and lateral fusion is probed by time‐resolved microscopy and electron diffraction. The gradual morphological and structural changes reveal the nonclassical crystal growth pathway, where the balance of strong and weak intermolecular interactions led to a structure beyond the nanoscale. The role of distinct π ‐stacking and H‐bonding interactions that drive the nonclassical crystallization process of Cr‐FF OEt supramolecular polymers is analyzed in comparison to analogous molecules, Py‐FF OEt and Cr‐FF forming helical and twisted fibers, respectively. Furthermore, the Cr‐FF OEt crystals formed through nonclassical crystallization are found to improve the functional properties

Recent Progress of 2D Layered Materials in Water-in-Salt/Deep Eutectic Solvent-Based Liquid Electrolytes for Supercapacitors

Supercapacitors are candidates with the greatest potential for use in sustainable energy resources. Extensive research is being carried out to improve the performances of state-of-art supercapacitors to meet our increased energy demands because of huge technological innovations in various fields. The development of high-performing materials for supercapacitor components such as electrodes, electrolytes, current collectors, and separators is inevitable. To boost research in materials design and production toward supercapacitors, the up-to-date collection of recent advancements is necessary for the benefit of active researchers. This review summarizes the most recent developments of water-in-salt (WIS) and deep eutectic solvents (DES), which are considered significant electrolyte systems to advance the energy density of supercapacitors, with a focus on two-dimensional layered nanomaterials. It provides a comprehensive survey of 2D materials (graphene, MXenes, and transition-metal oxides/dichalcogenides/sulfides) employed in supercapacitors using WIS/DES electrolytes. The synthesis and characterization of various 2D materials along with their electrochemical performances in WIS and DES electrolyte systems are described. In addition, the challenges and opportunities for the next-generation supercapacitor devices are summarily discussed

Urea-Based Deep Eutectic Solvent with Magnesium/Lithium Dual Ions as an Aqueous Electrolyte for High-Performance Battery-Supercapacitor Hybrid Devices

A new deep eutectic solvent (DES) made from urea, magnesium chloride, lithium perchlorate and water has been developed as the electrolyte for battery-supercapacitor hybrid devices. The physicochemical characteristics of DES electrolytes and potential interactions between electrolyte components are well analyzed through electrochemical and spectroscopic techniques. It has been discovered that the properties of DES electrolytes are highly dependent on the component ratio, which allows us to engineer the electrolyte to meet the requirement of the battery application. Perylene tetracarboxylic di-imide and reduced graphene oxide ha ve been combined to produce a composite (PTCDI/rGO) that has been tested as the anode in DES electrolyte. This composite shows that the capacitive contribution is greater than 90% in a low scan rate, resulting in the high rate capability. The PTCDI/rGO electrode exhibits no sign of capacity degradation and its coulombic efficiency is close to 99% after 200 cycles, which suggests excellent reversibility and stability. On the other hand, the electrochemical performance of lithium manganese oxide as the cathode material is studied in DES electrolyte, which exhibits the maximum capacity of 76.5 mAh/g at 0.03 A/g current density. After being successfully examined in terms of electrode kinetics, capacity performance, and rate capability, the anode and cathode materials are combined to construct a two-electrode system with DES electrolyte. At a current density of 0.03 A/g, this system offers 43.5 mAh/g specific capacity and displays 55.5% retention of the maximum capacity at 1 A/g. Furthermore, an energy density of 53 Wh/kg is delivered at a power density of 35 W/kg

Exfoliation of Reduced Graphene Oxide with Self-Assembled π‑Gelators for Improved Electrochemical Performance

Among several methodologies to improve the solution processing of graphene-based materials, noncovalent functionalization has been considered as the simplest and nondestructive method. Herein, we show that molecular self-assembly process can be used as a useful tool to exfoliate reduced graphene oxide (RGO), resulting in hybrid materials with improved physical properties. Upon interacting with a π-gelator, the dispersing ability of the RGO increased significantly in most of nonpolar and polar aprotic solvents when compared to the bare one. The amount of RGO dispersed was 1.7–1.8 mg mL^–1 in solvents such as toluene, <i>o</i>-dichlorobenzene (ODCB) and tetrahydrofuran (THF). Morphological studies revealed that aggregation of π-gelator over RGO helps to exfoliate graphene layers to remain as individual sheets with higher surface area. Experimental studies revealed enhanced surface area (250 m² g^–1) and better conductivity (3.7 S m^–1) of the hybrid materials with 30% of RGO content resulting in excellent electrochemical performance (specific capacitance of 181 F g^–1) as electrodes for supercapacitors