T cells use the αβ T cell receptor (TCR) to bind peptides presented by major histocompatibility complex proteins (pMHC) on antigen presenting cells. Formation of a TCR-pMHC complex initiates T cell signaling via a poorly understood process, potentially involving changes in oligomeric state, altered interactions with CD3 subunits, and mechanical stress. These mechanisms could be facilitated by binding-induced changes in the TCR, but the nature and extent of any such alterations are unclear. Using hydrogen/deuterium exchange, we demonstrate that ligation globally rigidifies the TCR, which via entropic and packing effects will promote associations with neighboring proteins and enhance the stability of existing complexes. TCR regions implicated in lateral associations and signaling are particularly affected. Computational modeling demonstrated a high degree of dynamic coupling between the TCR constant and variable domains that is dampened upon ligation. These results raise the possibility that TCR triggering could involve a dynamically driven, allosteric mechanism.

Merging the disciplines of green chemistry, ecotoxicology and ecology to develop environmentally-friendly industrial chemicals represents a significant collaborative challenge. This challenge can be met by extending already-informative standard toxicity and biodegradability assays to include further information about the potential persistence and biotransformation of pollutants in the environment. Development of ionic liquids (ILs) provides an ideal and proactive test system to determine several levels of environmental impact using academically interesting and industrially relevant green chemical prototypes. In this study, we investigated the biodegradability of three ILs, 1-butyl-3-methylpyridinium bromide, 1-hexyl-3-methylpyridinium bromide and 1-octyl-3-methylpyridinium bromide, by activated sludge microbial communities. We determined that all three ILs could be fully mineralized, but that only the octyl-substituted cation could be classified as "readily biodegradable". We directly examined biodegradation products of the ILs using reverse-phase high performance liquid chromatography/mass spectrometry and MS/MS methods, and identified several unique preliminary degradation products. Finally, we determined that IL-biodegradation products were less toxic than the initial compound to a standard aquatic test organism, Daphnia magna, suggesting that biodegradation in an aquatic environment would decrease toxicity hazards associated with the initial compound. This study provides further information about pyridinium IL-biodegradation and guidelines to structure future IL design and research.

This study identifies zwint-1 as a novel substrate for AurB during mitosis. Phosphorylation is required for outer kinetochore assembly during prometaphase. However, zwint-1 dephosphorylation is required at metaphase for checkpoint silencing.

The hydroxyl radical ((•)OH) is one of the main oxidative species in aqueous phase advanced oxidation processes, and its initial reactions with organic pollutants are important to understand the transformation and fate of organics in water environments. Insights into the kinetics and mechanism of (•)OH mediated degradation of the model environmental endocrine disruptor, dimethyl phthalate (DMP), have been obtained using radiolysis experiments and computational methods. The bimolecular rate constant for the (•)OH reaction with DMP was determined to be (3.2 ± 0.1) × 10(9) M(-1)s(-1). The possible reaction mechanisms of radical adduct formation (RAF), hydrogen atom transfer (HAT), and single electron transfer (SET) were considered. By comparing the experimental absorption spectra with the computational results, it was concluded that the RAF and HAT were the dominant reaction pathways, and OH-adducts ((•)DMPOH1, (•)DMPOH2) and methyl type radicals (•)DMP(-H)α were identified as dominated intermediates. Computational results confirmed the identification of transient species with maximum absorption around 260 nm as (•)DMPOH1 and (•)DMP(-H)α, and these radical intermediates then converted to monohydroxylated dimethyl phthalates and monomethyl phthalates. Experimental and computational analyses which elucidated the mechanism of (•)OH-mediated degradation of DMP are discussed in detail.

The Drosophila ninaG mutant is characterized by low levels of Rh1 rhodopsin, because of the inability to transport this rhodopsin from the endoplasmic reticulum to the rhabdomere.