A Chemical Approach to Assess the Impact of Post-translational Modification on MHC Peptide Binding and Effector Cell Engagement.

The human major histocompatibility complex (MHC) plays a pivotal role in the presentation of peptidic fragments from proteins, which can originate from self-proteins or from nonhuman antigens, such as those produced by viruses or bacteria. To prevent cytotoxicity against healthy cells, thymocytes expressing T cell receptors (TCRs) that recognize self-peptides are removed from circulation (negative selection), thus leaving T cells that recognize nonself-peptides. Current understanding suggests that post-translationally modified (PTM) proteins and the resulting peptide fragments they generate following proteolysis are largely excluded from negative selection; this feature means that PTMs can generate nonself-peptides that potentially contribute to the development of autoreactive T cells and subsequent autoimmune diseases.

Analysis of isomeric mixtures by molecular rotational resonance spectroscopy.

Recent developments in molecular rotational resonance (MRR) spectroscopy that have enabled its use as an analytical technique for the precise determination of molecular structure are reviewed. In particular, its use in the differentiation of isomeric compounds-including regioisomers, stereoisomers and isotopic variants-is discussed. When a mixture of isomers, such as resulting from a chemical reaction, is analyzed, it is highly desired to be able to unambiguously identify the structures of each of the components present, as well as quantify them, without requiring complex sample preparation or reference standards.

22% Efficiency Inverted Perovskite Photovoltaic Cell Using Cation-Doped Brookite TiO Top Buffer.

Simultaneously achieving high efficiency and high durability in perovskite solar cells is a critical step toward the commercialization of this technology. Inverted perovskite photovoltaic (IP-PV) cells incorporating robust and low levelized-cost-of-energy (LCOE) buffer layers are supposed to be a promising solution to this target. However, insufficient inventory of materials for back-electrode buffers substantially limits the development of IP-PV.

Enhanced Activity and Substrate Specificity by Site-Directed Mutagenesis for the P450 119 Peroxygenase Catalyzed Sulfoxidation of Thioanisole.

P450 119 peroxygenase was found to catalyze the sulfoxidation of thioanisole and the sulfonation of sulfoxide in the presence of -butyl hydroperoxide (TBHP) for the first time with turnover rates of 1549 min and 196 min respectively. Several mutants were designed to improve the peroxygenation activity and thioanisole specificity by site-directed mutagenesis. The F153G/T213G mutant gave an increase of sulfoxide yield and a decrease of sulfone yield.

nido↔closo Interconversion of Six-Vertex Metallacarboranes: Access to CoC B and CoC B Clusters with Nonadjacent Carbon Atoms.

Replacement of B-H hydrogen atoms with Cl or Br facilitates the previously unknown oxidative conversion of a nido- to a closo-6-vertex metallacarborane [Eq. (1); X=Cl, Br]. Oxidative cage closure, separation of carbon atoms upon thermal rearrangement, reductive cage opening, and cage expansion by boron insertion have all been applied to a single system, to afford synthetic access to new cluster types.