Dual-angle light scattering spectroscopy for calibration-free measurements of scatterer suspensions.

It can be difficult to employ optical techniques for analyzing biological structures smaller than or comparable to the wavelength of light, such as extracellular vesicles or some types of bacteria. Biological light scattering spectroscopy (LSS), developed to address this problem, has been successfully used for characterizing tissue on cellular and subcellular scales. At the same time, calibration with a reference sample of known optical properties can complicate LSS measurements.

A Single-Column Gas Chromatography Method for Quantifying Toxic Alcohols.

Background: Rapid identification and quantification of toxic alcohols and ethylene glycol is imperative for appropriate treatment. Clinical laboratories frequently rely on direct injection gas chromatography (GC) methods, but these methods require inlet maintenance and multiple GC systems. To overcome these challenges, we developed a single-column headspace GC method for both toxic alcohols and glycols that streamlines patient sample analysis for toxic alcohol ingestion.

Molecular basis for receptor tyrosine kinase A-loop tyrosine transphosphorylation.

A long-standing mystery shrouds the mechanism by which catalytically repressed receptor tyrosine kinase domains accomplish transphosphorylation of activation loop (A-loop) tyrosines. Here we show that this reaction proceeds via an asymmetric complex that is thermodynamically disadvantaged because of an electrostatic repulsion between enzyme and substrate kinases. Under physiological conditions, the energetic gain resulting from ligand-induced dimerization of extracellular domains overcomes this opposing clash, stabilizing the A-loop-transphosphorylating dimer.

Analytical and Clinical Validation of Two Commercially Available Immunoassays Used in the Detection of TSHR Antibodies.

Background: Graves disease is caused by autoantibodies that target the thyroid-stimulating hormone receptor (TSHR). Anti-TSHR autoantibody measurement is routinely performed to differentiate between Graves disease and other causes of hyperthyroidism. We evaluated the clinical performance of a reference laboratory bioassay [the Thyretain thyroid-stimulating immunoglobulin (TSI) Bioassay by Diagnostic Hybrids] and 2 commercially available immunoassays: the TSI Bridge immunoassay by Siemens and the thyroid-stimulating hormone receptor antibody (TRAb) immunoassay by Roche.

FACT Disrupts Nucleosome Structure by Binding H2A-H2B with Conserved Peptide Motifs.

FACT, a heterodimer of Spt16 and Pob3, is an essential histone chaperone. We show that the H2A-H2B binding activity that is central to FACT function resides in short acidic regions near the C termini of each subunit. Mutations throughout these regions affect binding and cause correlated phenotypes that range from mild to lethal, with the largest individual contributions unexpectedly coming from an aromatic residue and a nearby carboxylate residue within each domain.

Structure of the Spt16 middle domain reveals functional features of the histone chaperone FACT.

The histone chaperone FACT is an essential and abundant heterodimer found in all eukaryotes. Here we report a crystal structure of the middle domain of the large subunit of FACT (Spt16-M) to reveal a double pleckstrin homology architecture. This structure was found previously in the Pob3-M domain of the small subunit of FACT and in the related histone chaperone Rtt106, although Spt16-M is distinguished from these structures by the presence of an extended α-helix and a C-terminal addition.

To C or not to C: direct and indirect redox regulation of Src protein tyrosine kinase.

Src protein tyrosine kinase is a master regulator of cell proliferation by modulating cell metabolism, division, survival and migration, thus the mechanisms that regulate Src function are of great interest to cancer research. One emerging mode of Src regulation is its response to reactive oxygen species (ROS). ROS have historically been viewed as damaging agents in cells under oxidative stress, but recent studies establish H(2)O(2) as a secondary messenger to growth signals.

Direct and specific inactivation of protein tyrosine kinases in the Src and FGFR families by reversible cysteine oxidation.

Accumulating evidence suggests that protein tyrosine phosphorylation-based signaling pathways are under the regulation of reactive oxygen species. Although protein tyrosine phosphatases are directly regulated by reversible oxidation, it is not clear whether protein tyrosine kinases (PTKs) are also directly regulated by reduction/oxidation (redox). In this study we report a mechanism of direct oxidative inactivation specific for the PTKs in the Src and fibroblast growth factor receptor (FGFR) families, key enzymes in mammalian signal transduction.

Bacterial expression and characterization of catalytic loop mutants of SRC protein tyrosine kinase.

Protein tyrosine kinase Src is a key enzyme in mammalian signal transduction and an important target for anticancer drug discovery. Although recombinant expression in bacterial cells offers a convenient and rapid way for producing several other protein tyrosine kinases, active Src is difficult to produce in bacterial systems. However, a kinase-defective Src mutant (due to a single point mutation, Lys295Met) is expressed strongly in bacteria.

Docking-based substrate recognition by the catalytic domain of a protein tyrosine kinase, C-terminal Src kinase (Csk).

Protein tyrosine kinases are key enzymes of mammalian signal transduction. Substrate specificity is a fundamental property that determines the specificity and fidelity of signaling by protein tyrosine kinases. However, how protein tyrosine kinases recognize the protein substrates is not well understood.