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The enzymes that facilitate phosphate and sulfate hydrolysis are among the most proficient natural catalysts known to date. Interestingly, a large number of these enzymes are promiscuous catalysts that exhibit both phosphatase and sulfatase activities in the same active site and, on top of that, have also been demonstrated to efficiently catalyze the hydrolysis of other additional substrates with varying degrees of efficiency. Understanding the factors that underlie such multifunctionality is crucial both for understanding functional evolution in enzyme superfamilies and for the development of artificial enzymes. In this Current Topic, we have primarily focused on the structural and mechanistic basis for catalytic promiscuity among enzymes that facilitate both phosphoryl and sulfuryl transfer in the same active site, while comparing this to how catalytic promiscuity manifests in other promiscuous phosphatases. We have also drawn on the large number of experimental and computational studies of selected model systems in the literature to explore the different features driving the catalytic promiscuity of such enzymes. Finally, on the basis of this comparative analysis, we probe the plausible origins and determinants of catalytic promiscuity in enzymes that catalyze phosphoryl and sulfuryl transfer.

Haze events in China megacities involve the rapid oxidation of SO_2 to sulfate aerosol. Given the weak photochemistry that takes place in these optically thick hazes, it has been hypothesized that SO_2 is mostly oxidized by NO_2 emissions in the bulk of pH > 5.5 aerosols. Because NO_2(g) dissolution in water is very slow and aerosols are more acidic, we decided to test such a hypothesis. Herein, we report that > 95% of NO_2(g) disproportionates [2NO_2(g) + H_2O(l) = H+ + NO_3–(aq) + HONO (R1)] upon hitting the surface of NaHSO_3 aqueous microjets for < 50 μs, thereby giving rise to strong NO_3– (m/z 62) signals detected by online electrospray mass spectrometry, rather than oxidizing HSO_3– (m/z 81) to HSO_4– (m/z 97) in the relevant pH 3–6 range. Because NO_2(g) will be consumed via R1 on the surface of typical aerosols, the oxidation of S(IV) may in fact be driven by the HONO/NO_2– generated therein. S(IV) heterogeneous oxidation rates are expected to primarily depend on the surface density and liquid water content of the aerosol, which are enhanced by fine aerosol and high humidity. Whether aerosol acidity affects the oxidation of S(IV) by HONO/NO_2– remains to be elucidated.

Polyurea-based synthetic glycopolymers containing sulfated glucose, mannose, glucosamine, or lactose as pendant groups have been synthesized by step-growth polymerization of hexamethylene diisocyanate and corresponding secondary diamines. The obtained polymers were characterized by gel permeation chromatography, nuclear magnetic resonance spectroscopy, and Fourier transform infrared spectroscopy. The nonsulfated polymers showed similar results to the commercially available biomaterial polyurethane TECOFLEX in a platelet adhesion assay. The average degree of sulfation after reaction with SO3 was calculated from elemental analysis and found to be between three and four -OSO3 groups per saccharide. The blood-compatibility of the synthetic polymers was measured using activated partial thromboplastin time, prothrombin time, thrombin time, anti-IIa, and anti-Xa assays. Activated partial thromboplastin time, prothrombin time, and thrombin time results indicated that the mannose and lactose based polymers had the highest anticoagulant activities among all the sulfated polymers. The mechanism of action of the polymers appears to be mediated via an anti-IIa pathway rather than an anti-Xa pathway.

The renewability, biocompatibility, and mechanical properties of cellulose nanocrystals (CNCs) have made them an attractive material for numerous composite, biomedical, and rheological applications. However, for CNCs to shift from a laboratory curiosity to commercial applications, researchers must transition from CNCs extracted on the bench scale to material produced on an industrial scale. There are a number of companies currently producing kilogram to ton per day quantities of sulfuric acid-hydrolyzed CNCs as well as other nanocelluloses, as described herein. With the recent intensification of industrially produced CNCs and the variety of cellulose sources, hydrolysis methods, and purification procedures, the characterization of these materials becomes critical. This has further been justified by the past two decades of research that demonstrate that the CNC stability and behavior are highly dependent on the surface chemistry, surface charge density, and particle size. This work outlines key test methods that should be employed to characterize these properties to ensure a "known" starting material and consistent performance. Of the sulfuric acid-extracted CNCs examined, industrially produced material compared well with laboratory-made CNCs, exhibiting similar charge density, colloidal and thermal stability, crystallinity, morphology, and self-assembly behavior. In addition, it was observed that further purification of CNCs using Soxhlet extraction in ethanol had minimal impact on the nanoparticle properties and is unlikely to be necessary for many applications. Overall, the current standing of industrially produced CNCs is positive, suggesting that the evolution to commercial-scale applications will not be hindered by CNC production.

Atmospheric iron aerosol is a bioavailable essential nutrient playing a role in oceanic productivity. Using aerosol time-of-flight mass spectrometry (ATOFMS), the particle size (0.3–1.5 μm), chemical composition and mixing state of Fe-containing particles collected at two European urban sites (London and Barcelona) were characterized. Out of the six particle types accounting for the entire Fe–aerosol population, that arising from long-range transport (LRT) of fine Fe-containing particles (Fe–LRT, 54–82% across the two sites) was predominant. This particle type was found to be internally mixed with nitrate and not with sulfate, and likely mostly associated with urban traffic activities. This is in profound contrast with previous studies carried out in Asia, where the majority of iron-containing particles are mixed with sulfate and are of coal combustion origin. Other minor fine iron aerosol sources included mineral dust (8–11%), traffic brake wear material (1–17%), shipping/oil (1–6%), biomass combustion (4–13%) and vegetative debris (1–3%). Overall, relative to anthropogenic Asian Fe–sulfate dust, anthropogenic European dust internally mixed with additional key nutrients such as nitrate is likely to play a different role in ocean global biogeochemical cycles

Previous experiments demonstrated that aqueous OH radical oxidation of glyoxal yields low-volatility compounds. When this chemistry takes place in clouds and fogs, followed by droplet evaporation (or if it occurs in aerosol water), the products are expected to remain partially in the particle phase, forming secondary organic aerosol (SOA). Acidic sulfate exists ubiquitously in atmospheric water and has been shown to enhance SOA formation through aerosol phase reactions. In this work, we investigate how starting concentrations of glyoxal (30−3000 μM) and the presence of acidic sulfate (0−840 μM) affect product formation in the aqueous reaction between glyoxal and OH radical. The oxalic acid yield decreased with increasing precursor concentrations, and the presence of sulfuric acid did not alter oxalic acid concentrations significantly. A dilute aqueous chemistry model successfully reproduced oxalic acid concentrations, when the experiment was performed at cloud-relevant concentrations (glyoxal, This paper examines aqueous glyoxal chemistry in clouds and wet aerosols as a source of secondary organic aerosol.

Post-translational modification of proteins plays critical roles in regulating structure, stability, localization, and function. Sulfation of the phenolic side chain of tyrosine residues to form sulfotyrosine (sTyr) is a widespread modification of extracellular and integral membrane proteins, influencing the activities of these proteins in cellular adhesion, blood clotting, inflammatory responses, and pathogen infection. Tyrosine sulfation commonly occurs in sequences containing clusters of tyrosine residues and is incomplete at each site, resulting in heterogeneous mixtures of sulfoforms. Purification of individual sulfoforms is typically impractical. Therefore, the most promising approach to elucidate the influence of sulfation at each site is to prepare homogeneously sulfated proteins (or peptides) synthetically. This Account describes our recent progress in both development of such synthetic approaches and application of the resulting sulfopeptides and sulfoproteins to characterize the functional consequences of tyrosine sulfation. Initial synthetic studies used a cassette-based solid-phase peptide synthesis (SPPS) approach in which the side chain sulfate ester was protected to enable it to withstand Fmoc-based SPPS conditions. Subsequently, to address the need for efficient access to multiple sulfoforms of the same peptide, we developed a divergent solid-phase synthetic approach utilizing orthogonally side chain protected tyrosine residues. Using this methodology, we have carried out orthogonal deprotection and sulfation of up to three tyrosine residues within a given sequence, allowing access to all eight sulfoforms of a given target from a single solid-phase synthesis. With homogeneously sulfated peptides in hand, we have been able to probe the influence of tyrosine sulfation on biochemical function. Several of these studies focused on sulfated fragments of chemokine receptors, key mediators of leukocyte trafficking and inflammation. For the receptor CCR3, we showed that tyrosine sulfation enhances affinity and selectivity for binding to chemokine ligands, and we determined the structural basis of these affinity enhancements by NMR spectroscopy. Using a library of CCR5 sulfopeptides, we demonstrated the critical importance of sulfation at one specific site for supporting HIV-1 infection. Demonstrating the feasibility of producing homogeneously tyrosine-sulfated proteins, in addition to smaller peptides, we have used SPPS and native chemical ligation methods to synthesize the leech-derived antithrombotic protein hirudin P6, containing both tyrosine sulfation and glycosylation. Sulfation greatly enhanced inhibitory activity against thrombin, whereas addition of glycans to the sulfated protein decreased inhibition, indicating functional interplay between different post-translational modifications. In addition, the success of the ligation approach suggests that larger sulfoproteins could potentially be obtained by ligation of synthetic sulfopeptides to expressed proteins, using intein-based technology.

This study investigates dual C−Cl isotope fractionation during 1,1,1-TCA transformation by heat-activated persulfate (PS), hydrolysis/dehydrohalogenation (HY/DH) and Fe(0). Compound-specific chlorine isotope analysis of 1,1,1-TCA was performed for the first time, and transformation-associated isotope fractionation εCbulk and ε CIbulk values were −4.0 ± 0.2‰ and no chlorine isotope fractionation with PS, −1.6 ± 0.2‰ and −4.7 ± 0.1‰ for HY/DH, −7.8 ± 0.4‰ and −5.2 ± 0.2‰ with Fe(0). Distinctly different dual isotope slopes (Δ δ13C/Δδ37Cl): ∞ with PS, 0.33 ± 0.04 for HY/DH and 1.5 ± 0.1 with Fe(0) highlight the potential of this approach to identify abiotic degradation pathways of 1,1,1-TCA in the field. The trend observed with PS agreed with a C−H bond oxidation mechanism in the first reaction step. For HY/DH and Fe(0) pathways, different slopes were obtained although both pathways involve cleavage of a C−Cl bond in their initial reaction step. In contrast to the expected larger primary carbon isotope effects relative to chlorine for C−Cl bond cleavage, εCbulk < εClbulk was observed for HY/DH and in a similar range for reduction by Fe(0), suggesting the contribution of secondary chlorine isotope effects. Therefore, different magnitude of secondary chlorine isotope effects could at least be partly responsible for the distinct slopes between HY/DH and Fe(0) pathways. Following this dual isotope approach, abiotic transformation processes can unambiguously be identified and quantified.

The negative effects of oxygen on white wine quality and the various factors which influence it (including temperature, dissolved oxygen, pH, and free SO2) are well documented both at the sensory and compositional levels. What is less defined is the quantitative relationship between these parameters and the kinetics of the development of the negative effects of oxidation. The experiment presented here attempts to generate data which can be used to predictively model the oxidative degradation of white wines. Bottled wines were submitted to extreme conditions (45 °C temperature, O2 saturation) during 3 months witth samples taken every 15 days for both sensorial and chemical analysis (GC-O/FPD/MS, 420 nm). The synergistic effects of increasing temperature and O2 at lower pH are evident, both on the decrease in levels of terpene alcohols and norisoprenoids (which impart floral aromas), and on the development of off-flavors such as "honey-like", "boiled-potato", and "farm-feed" associated with the presence of phenylacetaldehyde, methional, and 1,1,6-trimethyl-1,2-dihydronaphthalene.

In Port wine, isomers of glycerol and acetaldehyde acetals have been found at total contents ranging from 9.4 to 175.3 mg/L. During oxidative aging, the concentrations of the 5-hydroxy-2-methyl-1,3-dioxane and 4-hydroxymethyl-2-methyl-1,3-dioxolane isomers increased with time showing a linear correlation (r > 0.95). The flavor threshold for the mixture of the four isomers was evaluated in wine at 100 mg/L. Thus, it is expected that they contribute to “old Port wine” aroma in wines older than 30 years. Experiments with model solutions and wine clearly demonstrated that SO2 combines with acetaldehyde and blocks the acetalization reaction. Keywords: 1,3-Dioxanes; 1,3-dioxolanes; acetalization; oxidative wine-aging

We report the first joint shipboard and airborne study focused on the chemical composition and water-uptake behavior of particulate ship emissions. The study focuses on emissions from the main propulsion engine of a Post-Panamax class container ship cruising off the central coast of California and burning heavy fuel oil. Shipboard sampling included micro-orifice uniform deposit impactors (MOUDI) with subsequent offline analysis, whereas airborne measurements involved a number of real-time analyzers to characterize the plume aerosol, aged from a few seconds to over an hour. The mass ratio of particulate organic carbon to sulfate at the base of the ship stack was 0.23 ± 0.03, and increased to 0.30 ± 0.01 in the airborne exhaust plume, with the additional organic mass in the airborne plume being concentrated largely in particles below 100 nm in diameter. The organic to sulfate mass ratio in the exhaust aerosol remained constant during the first hour of plume dilution into the marine boundary layer. The mass spectrum of the organic fraction of the exhaust aerosol strongly resembles that of emissions from other diesel sources and appears to be predominantly hydrocarbon-like organic (HOA) material. Background aerosol which, based on air mass back trajectories, probably consisted of aged ship emissions and marine aerosol, contained a lower organic mass fraction than the fresh plume and had a much more oxidized organic component. A volume-weighted mixing rule is able to accurately predict hygroscopic growth factors in the background aerosol but measured and calculated growth factors do not agree for aerosols in the ship exhaust plume. Calculated CCN concentrations, at supersaturations ranging from 0.1 to 0.33%, agree well with measurements in the ship-exhaust plume. Using size-resolved chemical composition instead of bulk submicrometer composition has little effect on the predicted CCN concentrations because the cutoff diameter for CCN activation is larger than the diameter where the mass fraction of organic aerosol begins to increase significantly. The particle number emission factor estimated from this study is 1.3 × 1016 (kg fuel)-1, with less than 1/10 of the particles having diameters above 100 nm; 24% of particles (>10 nm in diameter) activate into cloud droplets at 0.3% supersaturation. © 2009 American Chemical Society.

To study the potential hepatic metabolism of olive oil phenols, human hepatoma HepG2 cells were incubated for 2 and 18 h with hydroxytyrosol, tyrosol, and hydroxytyrosyl acetate, three phenolic constituents of olive oil. After incubation, culture media and cell lysates were hydrolyzed with β-glucuronidase and sulfatase and analyzed by LC-MS. In vitro methylation, glucuronidation, and sulfation of pure phenols were also performed. Methylated and glucuronidated forms of hydroxytyrosol were detected at 18 h of incubation, together with methylglucuronidated metabolites. Hydroxytyrosyl acetate was largely converted into free hydroxytyrosol and subsequently metabolized, yet small amounts of glucuronidated hydroxytyrosyl acetate were detected. Tyrosol was poorly metabolized, with

6 pages, 1 figure, 2 tables.-- PMID: 12926872 [PubMed].-- Printed version published Aug 27, 2003., Ten different gaseous treatments were evaluated for their efficacy in the keeping quality of cv. Napoleon table grapes during 38 days of storage at 0°C followed by 6 days of shelf life at 15°C in air. These storage methods included modified atmosphere packaging (MAP) with and without SO2 or natural fungicides (hexanal and hexenal), two controlled atmospheres (CA), and intermittent and continuous applications of O3. As a control, air atmosphere during cold storage was used. Most of the treatments applied kept the postharvest quality of the grapes, although the best results were obtained by the use of a MAP with 5 kPa of O2 plus 15 kPa of CO2 plus 80 kPa of N2. The total anthocyanin content at harvest was 170 ± 19 μg/g of fresh weight (fw) of grapes, which declined in most of the treatments applied and was reflected in the loss of red color. Peonidin 3-glucoside was detected at all sampling times as the major anthocyanin (always >50% from the total content). Treatments applied kept or decreased the total flavonol content from that measured at harvest (17 ± 1.4 μg/g of fw of berries). However, an increase of up to 2-fold in total stilbenoid content after shelf life for CA and O3 treatments was observed. At all sampling times for almost every treatment piceid concentration remained unaltered or slightly changed, whereas large increases were observed after shelf life for resveratrol (1.2 ± 0.6 μg/g of fw of grapes sampled at harvest), even up to 3- and 4-fold for O3-treated grapes and 2-fold for CA-treated ones. Therefore, improved techniques for the keeping quality of cv. Napoleon table grapes during long-term storage seem to maintain or enhance their antioxidant compound content., We are grateful to Frutas Maripí S.A. for providing table grapes, to Centro de Capacitaciones Agrarias (Molina de Segura, Murcia, Spain) for providing facilities, and to Drs. Ferreres and García-Viguera (CEBAS-CSIC, Murcia, Spain) for providing authentic samples of flavonoids. We are grateful to Spanish CICYT-FEDER (1FD-0760-C03-01) for financial support.

Soluble transition metals in particulate matter (PM) can generate reactive oxygen species in vivo by redox cycling, leading to oxidative stress and adverse health effects. Most metals, such as those from roadway traffic, are emitted in an insoluble form, but must be soluble for redox cycling. Here we present the mechanism of metals dissolution by highly acidic sulfate aerosol and the effect on particle oxidative potential (OP) through analysis of size distributions. Size-segregated ambient PM were collected from a road-side and representative urban site in Atlanta, GA. Elemental and organic carbon, ions, total and water-soluble metals, and water-soluble OP were measured. Particle pH was determined with a thermodynamic model using measured ionic species. Sulfate was spatially uniform and found mainly in the fine mode, whereas total metals and mineral dust cations were highest at the road-side site and in the coarse mode, resulting in a fine mode pH < 2 and near neutral coarse mode. Soluble metals and OP peaked at the intersection of these modes demonstrating that sulfate plays a key role in producing highly acidic fine aerosols capable of dissolving primary transition metals that contribute to aerosol OP. Sulfate-driven metals dissolution may account for sulfate-health associations reported in past studies. © 2017 American Chemical Society.