Elucidation of the Fe(IV)=O intermediate in the catalytic cycle of the halogenase SyrB2.

Mononuclear non-haem iron (NHFe) enzymes catalyse a broad range of oxidative reactions, including halogenation, hydroxylation, ring closure, desaturation and aromatic ring cleavage reactions. They are involved in a number of biological processes, including phenylalanine metabolism, the production of neurotransmitters, the hypoxic response and the biosynthesis of secondary metabolites. The reactive intermediate in the catalytic cycles of these enzymes is a high-spin S = 2 Fe(IV)=O species, which has been trapped for a number of NHFe enzymes, including the halogenase SyrB2 (syringomycin biosynthesis enzyme 2).

Lymphoid tissue phospholipase A2 group IID resolves contact hypersensitivity by driving antiinflammatory lipid mediators.

Resolution of inflammation is an active process that is mediated in part by antiinflammatory lipid mediators. Although phospholipase A2 (PLA2) enzymes have been implicated in the promotion of inflammation through mobilizing lipid mediators, the molecular entity of PLA2 subtypes acting upstream of antiinflammatory lipid mediators remains unknown. Herein, we show that secreted PLA2 group IID (PLA2G2D) is preferentially expressed in CD11c(+) dendritic cells (DCs) and macrophages and displays a pro-resolving function.

Function of the diiron cluster of Escherichia coli class Ia ribonucleotide reductase in proton-coupled electron transfer.

The class Ia ribonucleotide reductase (RNR) from Escherichia coli employs a free-radical mechanism, which involves bidirectional translocation of a radical equivalent or "hole" over a distance of ~35 Å from the stable diferric/tyrosyl-radical (Y122(•)) cofactor in the β subunit to cysteine 439 (C439) in the active site of the α subunit. This long-range, intersubunit electron transfer occurs by a multistep "hopping" mechanism via formation of transient amino acid radicals along a specific pathway and is thought to be conformationally gated and coupled to local proton transfers. Whereas constituent amino acids of the hopping pathway have been identified, details of the proton-transfer steps and conformational gating within the β sununit have remained obscure; specific proton couples have been proposed, but no direct evidence has been provided.

Public preferences regarding informed consent models for participation in population-based genomic research.

Purpose: Some large population biobanks that house biospecimens and health information for research seek broad consent from participants, whereas others reconsent for specific new studies. Understanding research participants' attitudes and preferences about broad and narrow consent may improve recruitment, retention, and public support.

Methods: An online survey was conducted among a representative sample of 4,659 US adults to examine relationships between consent preferences and demographic factors, beliefs about privacy and the value of research, and the perceived trustworthiness of researchers.

Regulation and function of epithelial secreted phospholipase A2 group X in asthma.

Rationale: Indirect airway hyperresponsiveness (AHR) is a fundamental feature of asthma that is manifest as exercise-induced bronchoconstriction (EIB). Secreted phospholipase A2 group X (sPLA2-X) plays a key role in regulating eicosanoid formation and the development of inflammation and AHR in murine models.

Objectives: We sought to examine sPLA2-X in the airway epithelium and airway wall of patients with asthma, the relationship to AHR in humans, and the regulation and function of sPLA2-X within the epithelium.

Adsorption of copper, cadmium, lead and zinc onto a synthetic manganese oxide.

Due to its simple and inexpensive synthesis, a new amorphous hydrous manganese oxide (AMO) has been studied as a possible chemical stabilizing agent for soils contaminated with metals. Preliminary experiments evaluating the stability of AMO in pure water have reported only minor dissolution (5.70% and 0.

Attitudes about regulation among direct-to-consumer genetic testing customers.

Introduction: The first regulatory rulings by the U.S. Food and Drug Administration on direct-to-consumer (DTC) genetic testing services are expected soon.

Key role of group v secreted phospholipase A2 in Th2 cytokine and dendritic cell-driven airway hyperresponsiveness and remodeling.

Background: Previous work has shown that disruption of the gene for group X secreted phospholipase A2 (sPLA2-X) markedly diminishes airway hyperresponsiveness and remodeling in a mouse asthma model. With the large number of additional sPLA2s in the mammalian genome, the involvement of other sPLA2s in the asthma model is possible - in particular, the group V sPLA2 (sPLA2-V) that like sPLA2-X is highly active at hydrolyzing membranes of mammalian cells.

Methodology And Principal Findings: The allergen-driven asthma phenotype was significantly reduced in sPLA2-V-deficient mice but to a lesser extent than observed previously in sPLA2-X-deficient mice.

The influence of copper on tebuconazole sorption onto soils, humic substances, and ferrihydrite.

The aim of this study is to investigate how the presence of Cu influences tebuconazole (Teb) sorption onto contrasting soil types and two important constituents of the soil sorption complex: hydrated Fe oxide and humic substances. Tebuconazole was used in commercial form and as an analytical-grade chemical at different Teb/Cu molar ratios (1:4, 1:1, 4:1, and Teb alone). Increased Cu concentrations had a positive effect on tebuconazole sorption onto most soils and humic substances, probably as a result of Cu-Teb tertiary complexes on the soil surfaces.

Radical-translocation intermediates and hurdling of pathway defects in "super-oxidized" (Mn(IV)/Fe(IV)) Chlamydia trachomatis ribonucleotide reductase.

A class I ribonucleotide reductase (RNR) uses either a tyrosyl radical (Y(•)) or a Mn(IV)/Fe(III) cluster in its β subunit to oxidize a cysteine residue ∼35 Å away in its α subunit, generating a thiyl radical that abstracts hydrogen (H(•)) from the substrate. With either oxidant, the inter-subunit "hole-transfer" or "radical-translocation" (RT) process is thought to occur by a "hopping" mechanism involving multiple tyrosyl (and perhaps one tryptophanyl) radical intermediates along a specific pathway. The hopping intermediates have never been directly detected in a Mn/Fe-dependent (class Ic) RNR nor in any wild-type (wt) RNR.

Spectroscopy and thermometry of drumhead modes in a mesoscopic trapped-ion crystal using entanglement.

We demonstrate spectroscopy and thermometry of individual motional modes in a mesoscopic 2D ion array using entanglement-induced decoherence as a method of transduction. Our system is a ~400 μm-diameter planar crystal of several hundred 9Be(+) ions exhibiting complex drumhead modes in the confining potential of a Penning trap. Exploiting precise control over the 9Be(+) valence electron spins, we apply a homogeneous spin-dependent optical dipole force to excite arbitrary transverse modes with an effective wavelength approaching the interparticle spacing (~20 μm).

Evidence for only oxygenative cleavage of aldehydes to alk(a/e)nes and formate by cyanobacterial aldehyde decarbonylases.

Cyanobacterial aldehyde decarbonylases (ADs) catalyze the conversion of C(n) fatty aldehydes to formate (HCO(2)(-)) and the corresponding C(n-1) alk(a/e)nes. Previous studies of the Nostoc punctiforme (Np) AD produced in Escherichia coli (Ec) showed that this apparently hydrolytic reaction is actually a cryptically redox oxygenation process, in which one O-atom is incorporated from O(2) into formate and a protein-based reducing system (NADPH, ferredoxin, and ferredoxin reductase; N/F/FR) provides all four electrons needed for the complete reduction of O(2). Two subsequent publications by Marsh and co-workers [ Das, et al.

Engineered two-dimensional Ising interactions in a trapped-ion quantum simulator with hundreds of spins.

The presence of long-range quantum spin correlations underlies a variety of physical phenomena in condensed-matter systems, potentially including high-temperature superconductivity. However, many properties of exotic, strongly correlated spin systems, such as spin liquids, have proved difficult to study, in part because calculations involving N-body entanglement become intractable for as few as N ≈ 30 particles. Feynman predicted that a quantum simulator--a special-purpose 'analogue' processor built using quantum bits (qubits)--would be inherently suited to solving such problems.

Preferences for opt-in and opt-out enrollment and consent models in biobank research: a national survey of Veterans Administration patients.

Purpose: In 2006, the Department of Veterans Affairs launched the Genomic Medicine Program with the goal of using genomic information to personalize and improve health care for veterans. A step toward this goal is the Million Veteran Program, which aims to enroll a million veterans in a longitudinal cohort study and establish a database with genomic, lifestyle, military-exposure, and health information. Before the launch of the Million Veteran Program, a survey of Department of Veterans Affairs patients was conducted to measure preferences for opt-in and opt-out models of enrollment and consent.

Electronic structure analysis of the oxygen-activation mechanism by Fe(II)- and α-ketoglutarate (αKG)-dependent dioxygenases.

α-Ketoglutarate (αKG)-dependent nonheme iron enzymes utilize a high-spin (HS) ferrous center to couple the activation of oxygen to the decarboxylation of the cosubstrate αKG to yield succinate and CO(2), and to generate a high-valent ferryl species that then acts as an oxidant to functionalize the target C-H bond. Herein a detailed analysis of the electronic-structure changes that occur in the oxygen activation by this enzyme was performed. The rate-limiting step, which is identical on the septet and quintet surfaces, is the nucleophilic attack of the distal O atom of the O(2) adduct on the carbonyl group in αKG through a bicyclic transition state ((5, 7) TS1).

High-throughput assay of secreted phospholipases A₂ inhibitors.

Attempts to characterize, quantify, and/or modulate the activity of the secreted phospholipase A(2) family of enzymes result from the diversity of physiological roles for which these enzymes have been implicated. The 1-palmitoyl-2-(10-pyrenedecanoyl)-phosphatidylglycerol (pyrenePG)-based fluorometric assay is a sensitive and readily adaptable method for further elucidating phospholipase function under various experimental conditions, as well as a tool for screening chemical libraries for potent inhibitors of this enzymatic activity. This assay is based on the observed difference in fluorescent emission of pyrene aggregated in vesicles compared to sequestered in monomeric form by binding to bovine serum albumin after lipolytic activity, thus allowing direct quantification of hydrolyzed fatty acids by the measurement of the corresponding monomeric emission intensity.

Public preferences regarding the return of individual genetic research results: findings from a qualitative focus group study.

Purpose: People are interested in receiving their individual research results in exchange for participating in genetic research. However, it is unclear whether the public understands the nature and limitations of these results and whether they would want information with unknown clinical utility.

Methods: We conducted 10 focus groups in three US cities to examine the types of results people would want and the perceived value of different types of individual research results.

Column leaching of chromium and nickel from a contaminated soil using EDTA and citric acid.

This study investigates the column leaching of a soil contaminated mainly with Cr and Ni by using two chelants: citric acid (biodegradable) and EDTA (non-biodegradable) followed with water rinse. The chelants lead to Cr and Ni leaching, in addition to major elements (Ca, Fe, Mg, Al, Mn and Zn) showing the dissolution of soil mineral constituents. EDTA leaches more major elements and Ni than citric acid related to the respective stability of metal-chelant complexes; citric acid leaches more Cr than EDTA, certainly because of a substitution reaction with Cr(VI).

O(2)-evolving chlorite dismutase as a tool for studying O(2)-utilizing enzymes.

The direct interrogation of fleeting intermediates by rapid-mixing kinetic methods has significantly advanced our understanding of enzymes that utilize dioxygen. The gas's modest aqueous solubility (<2 mM at 1 atm) presents a technical challenge to this approach, because it limits the rate of formation and extent of accumulation of intermediates. This challenge can be overcome by use of the heme enzyme chlorite dismutase (Cld) for the rapid, in situ generation of O(2) at concentrations far exceeding 2 mM.

Risky business: risk perception and the use of medical services among customers of DTC personal genetic testing.

Direct-to-consumer genetic testing has generated speculation about how customers will interpret results and how these interpretations will influence healthcare use and behavior; however, few empirical data on these topics exist. We conducted an online survey of DTC customers of 23andMe, deCODEme, and Navigenics to begin to address these questions. Random samples of U.

Evidence that the β subunit of Chlamydia trachomatis ribonucleotide reductase is active with the manganese ion of its manganese(IV)/iron(III) cofactor in site 1.

The reaction of a class I ribonucleotide reductase (RNR) begins when a cofactor in the β subunit oxidizes a cysteine residue ~35 Å away in the α subunit, generating a thiyl radical. In the class Ic enzyme from Chlamydia trachomatis (Ct), the cysteine oxidant is the Mn(IV) ion of a Mn(IV)/Fe(III) cluster, which assembles in a reaction between O(2) and the Mn(II)/Fe(II) complex of β. The heterodinuclear nature of the cofactor raises the question of which site, 1 or 2, contains the Mn(IV) ion.

Diminished top-down control underlies a visual imagery deficit in normal aging.

Mental imagery is involved in a wide variety of cognitive abilities, including reasoning, spatial navigation, and memory. Cognitive aging is associated with impairments in these abilities, suggesting that diminished fidelity of mental images in older adults may be related to diverse cognitive deficits. However, an age-related deficit in mental imagery and its role in memory impairment is still a matter of debate.

Branched intermediate formation is the slowest step in the protein splicing reaction of the Ala1 KlbA intein from Methanococcus jannaschii.

We report the first detailed investigation of the kinetics of protein splicing by the Methanococcus jannaschii KlbA (Mja KlbA) intein. This intein has an N-terminal Ala in place of the nucleophilic Cys or Ser residue that normally initiates splicing but nevertheless splices efficiently in vivo [Southworth, M. W.

Age-related changes in orienting attention in time.

Temporal cues guide attentional resources toward relevant points in time, resulting in optimized behavioral performance. Although deficits in aspects of attention have been documented in older adults, it remains unknown whether the critical ability to orient attention in time is affected by normal aging. To address this, younger and older adults participated in a temporally cued target-response experiment while electroencephalographic data were recorded.