Enhancement effects of ultrasound assisted in the synthesis of NiAl hydrotalcite for carbonyl sulfide removal.
Ultrasonics Sonochemistry 32:336 (2016)
Ultrasonic effect in the synthesis of catalysts of NiAl oxides prepared starting from the coprecipitation method of a hydrotalcite structure was evaluated in this work. Removal of carbonyl sulfide (COS) at low temperature over the hydrotalcite-derived oxides was studied. The samples were charact...
Biophysical and Biochemical Characterization of Avian Secretory Component Provides Structural Insights into the Evolution of the Polymeric Ig Receptor.
Journal of Immunology 197(4):1408 (2016)
The polymeric Ig receptor (pIgR) transports polymeric Abs across epithelia to the mucosa, where proteolytic cleavage releases the ectodomain (secretory component [SC]) as an integral component of secretory Abs, or as an unliganded protein that can mediate interactions with bacteria. SC is conser...
A triarylmethyl spin label for long-range distance measurement at physiological temperatures using T1 relaxation enhancement.
Site-directed spin labeling (SDSL) in combination with electron paramagnetic resonance (EPR) spectroscopy has become an important tool for measuring distances in proteins on the order of a few nm. For this purpose pairs of spin labels, most commonly nitroxides, are site-selectively introduced in...
Knockdown of delta-5-desaturase promotes the anti-cancer activity of dihomo-γ-linolenic acid and enhances the efficacy of chemotherapy in colon cancer cells expressing COX-2.
Free Radical Biology and Medicine 96:67 (2016)
Cyclooxygenase (COX), commonly overexpressed in cancer cells, is a major lipid peroxidizing enzyme that metabolizes polyunsaturated fatty acids (ω-3s and ω-6s). The COX-catalyzed free radical peroxidation of arachidonic acid (ω-6) can produce deleterious metabolites (e.g. 2-series prostaglandins...
Steric trapping reveals a cooperativity network in the intramembrane protease GlpG.
Nature Chemical Biology 12(5):353 (2016)
Membrane proteins are assembled through balanced interactions among proteins, lipids and water. Studying their folding while maintaining the native lipid environment is necessary but challenging. Here we present methods for analyzing key elements of membrane protein folding including thermodynam...
Conformational Mobility in Cytochrome P450 3A4 Explored by Pressure-Perturbation EPR Spectroscopy.
Biophysical Journal 110(7):1485 (2016)
We used high hydrostatic pressure as a tool for exploring the conformational landscape of human cytochrome P450 3A4 (CYP3A4) by electron paramagnetic resonance and fluorescence spectroscopy. Site-directed incorporation of a luminescence resonance energy transfer donor-acceptor pair allowed us to...
Conformational Flexibility Enables the Function of a BECN1 Region Essential for Starvation-Mediated Autophagy.
Biochemistry (Washington) 55(13):1945 (2016)
BECN1 is essential for autophagy, a critical eukaryotic cellular homeostasis pathway. Here we delineate a highly conserved BECN1 domain located between previously characterized BH3 and coiled-coil domains and elucidate its structure and role in autophagy. The 2.0 Å sulfur-single-wavelength anoma...
The structure and dynamics of secretory component and its interactions with polymeric immunoglobulins.
eLife 5 (2016)
As a first-line vertebrate immune defense, the polymeric immunoglobulin receptor (pIgR) transports polymeric IgA and IgM across epithelia to mucosal secretions, where the cleaved ectodomain (secretory component; SC) becomes a component of secretory antibodies, or when unliganded, binds and exclu...
Structural Insights into the Dynamic Process of β2-Adrenergic Receptor Signaling
Cell 162(6):1431 (2015)
SIGNAL TRANSDUCTION. Structural basis for nucleotide exchange in heterotrimeric G proteins.
Science 348(6241):1361 (2015)
G protein-coupled receptors (GPCRs) relay diverse extracellular signals into cells by catalyzing nucleotide release from heterotrimeric G proteins, but the mechanism underlying this quintessential molecular signaling event has remained unclear. Here we use atomic-level simulations to elucidate t...
Structural Insights into the Dynamic Process of β2-Adrenergic Receptor Signaling.
Cell 161(5):1101 (2015)
G-protein-coupled receptors (GPCRs) transduce signals from the extracellular environment to intracellular proteins. To gain structural insight into the regulation of receptor cytoplasmic conformations by extracellular ligands during signaling, we examine the structural dynamics of the cytoplasmi...
Structure-relaxation mechanism for the response of T4 lysozyme cavity mutants to hydrostatic pressure.
PNAS 112(19):E2437 (2015)
Application of hydrostatic pressure shifts protein conformational equilibria in a direction to reduce the volume of the system. A current view is that the volume reduction is dominated by elimination of voids or cavities in the protein interior via cavity hydration, although an alternative mecha...
Cu²⁺ as an ESR Probe of Protein Structure and Function.
Methods in Enzymology 563:459 (2015)
Electron spin resonance (ESR) spectroscopy in combination with site-directed spin labeling has been widely used to determine the structure and dynamics of proteins and other biomolecules. The most popular spin label is a nitroxide-based radical which can be attached to a protein via a site-speci...
Saturation Recovery EPR and Nitroxide Spin Labeling for Exploring Structure and Dynamics in Proteins.
Methods in Enzymology 564:3 (2015)
Experimental techniques capable of determining the structure and dynamics of proteins are continuously being developed in order to understand protein function. Among existing methods, site-directed spin labeling in combination with saturation recovery (SR) electron paramagnetic resonance spectro...
High-Pressure EPR and Site-Directed Spin Labeling for Mapping Molecular Flexibility in Proteins.
Methods in Enzymology 564:29 (2015)
High hydrostatic pressure is a powerful probe of protein conformational flexibility. Pressurization reveals regions of elevated compressibility, and thus flexibility, within individual conformational states, but also shifts conformational equilibria such that "invisible" excited states become ac...
Long-range distance measurements in proteins at physiological temperatures using saturation recovery EPR spectroscopy.
Journal of the American Chemical Society 136(43):15356 (2014)
Site-directed spin labeling in combination with EPR is a powerful method for providing distances on the nm scale in biological systems. The most popular strategy, double electron-electron resonance (DEER), is carried out at cryogenic temperatures (50-80 K) to increase the short spin-spin relaxat...
Structural and energetic determinants of adhesive binding specificity in type I cadherins.
PNAS 111(40):E4175 (2014)
Type I cadherin cell-adhesion proteins are similar in sequence and structure and yet are different enough to mediate highly specific cell-cell recognition phenomena. It has previously been shown that small differences in the homophilic and heterophilic binding affinities of different type I fami...
Identification of a unique Fe-S cluster binding site in a glycyl-radical type microcompartment shell protein.
Journal of Molecular Biology 426(19):3287 (2014)
Recently, progress has been made toward understanding the functional diversity of bacterial microcompartment (MCP) systems, which serve as protein-based metabolic organelles in diverse microbes. New types of MCPs have been identified, including the glycyl-radical propanediol (Grp) MCP. Within th...
Mapping protein conformational heterogeneity under pressure with site-directed spin labeling and double electron-electron resonance.
PNAS 111(13):E1201 (2014)
The dominance of a single native state for most proteins under ambient conditions belies the functional importance of higher-energy conformational states (excited states), which often are too sparsely populated to allow spectroscopic investigation. Application of high hydrostatic pressure increa...
Structural and Energetic Determinants of Adhesive Binding Specificity in Type I Cadherins: The Role of Multiple Conformations in Tuning Affinities
Biophysical Journal 106(2):464a (2014)