Structure of human MRG15 chromo domain and its binding to Lys36-methylated histone H3

Human MRG15 is a transcription factor that plays a vital role in embryonic development, cell proliferation and cellular senescence. It comprises a putative chromo domain in the N-terminal part that has been shown to participate in chromatin remodeling and transcription regulation. We report here the crystal structure of human MRG15 chromo domain at 2.2 Å resolution. The MRG15 chromo domain consists of a β-barrel and a long α-helix and assumes a structure more similar to the Drosophila MOF chromo barrel domain than the typical HP1/Pc chromo domains. The β-barrel core contains a hydrophobic pocket formed by three conserved aromatic residues Tyr26, Tyr46 and Trp49 as a potential binding site for a modified residue of histone tail. However, the binding groove for the histone tail seen in the HP1/Pc chromo domains is pre-occupied by an extra β-strand. In vitro binding assay results indicate that the MRG15 chromo domain can bind to methylated Lys36, but not methylated Lys4, Lys9 and Lys27 of histone H3. These data together suggest that the MRG15 chromo domain may function as an adaptor module which can bind to a modified histone H3 in a mode different from that of the HP1/Pc chromo domains

Dominating Role of Aligned MoS₂/Ni₃S₂ Nanoarrays Supported on Three-Dimensional Ni Foam with Hydrophilic Interface for Highly Enhanced Hydrogen Evolution Reaction

When using water splitting to achieve sustainable hydrogen production, low-cost, stable, and naturally abundant electrocatalysts are required to replace Pt-based ones for the hydrogen evolution reaction (HER). Herein, for the first time, a novel nanostructure with one-dimensional (1D) MoS₂/Ni₃S₂ nanoarrays directly grow on a three-dimensional (3D) Ni foam is developed for this purpose, showing excellent catalytic activity and stability. The as-prepared 3D MoS₂/Ni₃S₂/Ni composite has an onset overpotential as low as 13 mV in 1 M KOH, which is comparable to Pt-based electrocatalyst for HER. According to the classical theory, the Tafel slope of the new composite is relatively low, as it goes through a combined Volmer–Heyrovsky mechanism during hydrogen evolution. All the results attribute the excellent electrocatalytic activity of the nanostructure to the electrical coupling among Ni, Ni₃S₂, and MoS₂, the super hydrophilic interface, the synergistic catalytic effects produced by the MoS₂/Ni₃S₂ nanoarrays, and abundant exposed active edge sites. These unique and previously undeveloped characteristics of the 3D MoS₂/Ni₃S₂/Ni composite make it a very promising earth-abundant electrocatalyst for HER

TEM images of MoS₂ NSs/rGO.

<p>TEM images of MoS₂ NSs/rGO.</p

MoS₂ nanosheets direct supported on reduced graphene oxide: An advanced electrocatalyst for hydrogen evolution reaction - Fig 3

<p>Polarization curves for the catalysts of MoS₂ NSs, MoS₂ NSs/rGO (5 wt.%, 13 wt.% and 20 wt.%.), and Pt/C (a) and their corresponding Tafel plots (b). Impedance spectroscopy at an overpotential of 120 mV (c). Durability test for MoS₂ NSs/rGO hybrid catalyst (d). The inset is TEM image of the MoS₂ NSs/rGO hybrid after 2000 cycles.</p

Schematic illustration of the mechanism governing the catalytic HER on the MoS₂ NSs/rGO structure.

<p>Schematic illustration of the mechanism governing the catalytic HER on the MoS₂ NSs/rGO structure.</p

Free MoS₂ Nanoflowers Grown on Graphene by Microwave-Assisted Synthesis as Highly Efficient Non-Noble-Metal Electrocatalysts for the Hydrogen Evolution Reaction

<div><p>Advanced approaches to preparing non-noble-metal electrocatalysts for the hydrogen evolution reaction (HER) are considered to be a significant breakthrough in promoting the exploration of renewable resources. In this work, a hybrid material of MoS₂ nanoflowers (NFs) on reduced graphene oxide (rGO) was synthesized as a HER catalyst via an environmentally friendly, efficient approach that is also suitable for mass production. Small-sized MoS₂ NFs with a diameter of ca. 190 nm and an abundance of exposed edges were prepared by a hydrothermal method and were subsequently supported on rGO by microwave-assisted synthesis. The results show that MoS₂ NFs were distributed uniformly on the remarkably reduced GO and preserved the outstanding original structural features perfectly. Electrochemical tests show that the as-prepared hybrid material exhibited excellent HER activity, with a small Tafel slope of 80 mV/decade and a low overpotential of 170 mV.</p></div

Modifications on Promoting the Proton Conductivity of Polybenzimidazole-Based Polymer Electrolyte Membranes in Fuel Cells

Hydrogen-air proton exchange membrane fuel cells (PEMFCs) and direct methanol fuel cells (DMFCs) are excellent fuel cells with high limits of energy density. However, the low carbon monoxide (CO) tolerance of the Pt electrode catalyst in hydrogen-air PEMFCs and methanol permanent in DMFCs greatly hindered their extensive use. Applying polybenzimidazole (PBI) membranes can avoid these problems. The high thermal stability allows PBI membranes to work at elevated temperatures when the CO tolerance can be significantly improved; the excellent methanol resistance also makes it suitable for DMFCs. However, the poor proton conductivity of pristine PBI makes it hard to be directly applied in fuel cells. In the past decades, researchers have made great efforts to promote the proton conductivity of PBI membranes, and various effective modification methods have been proposed. To provide engineers and researchers with a basis to further promote the properties of fuel cells with PBI membranes, this paper reviews critical researches on the modification of PBI membranes in both hydrogen-air PEMFCs and DMFCs aiming at promoting the proton conductivity. The modification methods have been classified and the obtained properties have been included. A guide for designing modifications on PBI membranes for high-performance fuel cells is provided

(a) Several catalysts polarization curves and MoS₂ NFs/rGO hybrid catalyst durability test. (b) Several catalysts Tafel plots (overpotential versus log current). Inset in (b) shows the bubble generated by MoS₂ NFs and MoS₂ NFs/rGO in a cycling.

<p>(a) Several catalysts polarization curves and MoS₂ NFs/rGO hybrid catalyst durability test. (b) Several catalysts Tafel plots (overpotential versus log current). Inset in (b) shows the bubble generated by MoS₂ NFs and MoS₂ NFs/rGO in a cycling.</p

MoS₂ NFs/rGO hybrid preparation.

<p>MoS₂ NFs/rGO hybrid preparation.</p