Diethyl [2,2,2-trifluoro-1-phenyl­sulfonyl­amino-1-(trifluoro­meth­yl)eth­yl]phospho­nate

The title compound, C13H16F6NO5PS, is of inter­est with respect to inhibition of serine hydro­lases. Its structure contains a 1.8797 (13) Å P—C bond and two inter­molecular N—H⋯O=P hydrogen bonds, resulting in centrosymmetric dimers. An intra­molecular N—H⋯O=P hydrogen bond is also present

Identification of emulsifier potato peptides by bioinformatics: application to omega-3 delivery emulsions and release from potato industry side streams

We are grateful for the financial support from Innovation Fund Denmark (Grant nr: 7045-00021B, PROVIDE project). We also acknowledge K.M.C. amba (Brande, Denmark) and A.K.V. amba (Langholt, Denmark) for providing the potato samples used in this study.In this work, we developed a novel approach combining bioinformatics, testing of functionality and bottom-up proteomics to obtain peptide emulsifiers from potato side-streams. This is a significant advancement in the process to obtain emulsifier peptides and it is applicable to any type of protein. Our results indicated that structure at the interface is the major determining factor of the emulsifying activity of peptide emulsifiers. Fish oil-in-water emulsions with high physical stability were stabilized with peptides to be predicted to have facial amphiphilicity: (i) peptides with predominantly α-helix conformation at the interface and having 18–29 amino acids, and (ii) peptides with predominantly β-strand conformation at the interface and having 13–15 amino acids. In addition, high physically stable emulsions were obtained with peptides that were predicted to have axial hydrophobic/hydrophilic regions. Peptides containing the sequence FCLKVGV showed high in vitro antioxidant activity and led to emulsions with high oxidative stability. Peptide-level proteomics data and sequence analysis revealed the feasibility to obtain the potent emulsifier peptides found in this study (e.g. γ-1) by trypsin-based hydrolysis of different side streams in the potato industry.Innovation Fund Denmark 7045-00021

CATMoS: Collaborative Acute Toxicity Modeling Suite.

BACKGROUND: Humans are exposed to tens of thousands of chemical substances that need to be assessed for their potential toxicity. Acute systemic toxicity testing serves as the basis for regulatory hazard classification, labeling, and risk management. However, it is cost- and time-prohibitive to evaluate all new and existing chemicals using traditional rodent acute toxicity tests. In silico models built using existing data facilitate rapid acute toxicity predictions without using animals. OBJECTIVES: The U.S. Interagency Coordinating Committee on the Validation of Alternative Methods (ICCVAM) Acute Toxicity Workgroup organized an international collaboration to develop in silico models for predicting acute oral toxicity based on five different end points: Lethal Dose 50 (LD50 value, U.S. Environmental Protection Agency hazard (four) categories, Globally Harmonized System for Classification and Labeling hazard (five) categories, very toxic chemicals [LD50 (LD50≤50mg/kg)], and nontoxic chemicals (LD50>2,000mg/kg). METHODS: An acute oral toxicity data inventory for 11,992 chemicals was compiled, split into training and evaluation sets, and made available to 35 participating international research groups that submitted a total of 139 predictive models. Predictions that fell within the applicability domains of the submitted models were evaluated using external validation sets. These were then combined into consensus models to leverage strengths of individual approaches. RESULTS: The resulting consensus predictions, which leverage the collective strengths of each individual model, form the Collaborative Acute Toxicity Modeling Suite (CATMoS). CATMoS demonstrated high performance in terms of accuracy and robustness when compared with in vivo results. DISCUSSION: CATMoS is being evaluated by regulatory agencies for its utility and applicability as a potential replacement for in vivo rat acute oral toxicity studies. CATMoS predictions for more than 800,000 chemicals have been made available via the National Toxicology Program's Integrated Chemical Environment tools and data sets (ice.ntp.niehs.nih.gov). The models are also implemented in a free, standalone, open-source tool, OPERA, which allows predictions of new and untested chemicals to be made. https://doi.org/10.1289/EHP8495

Crystal structure of patatin-17 in complex with aged and non-aged organophosphorus compounds.

Patatin is a non-specific plant lipase and the eponymous member of a broad class of serine hydrolases termed the patatin-like phospholipase domain containing proteins (PNPLAs). Certain PNPLA family members can be inhibited by organophosphorus (OP) compounds. Currently, no structural data are available on the modes of interaction between the PNPLAs and OP compounds or their native substrates. To this end, we present the crystal structure of patatin-17 (pat17) in its native state as well as following inhibition with methyl arachidonyl fluorophosphonate (MAFP) and inhibition/aging with diisopropylphosphorofluoridate (DFP). The native pat17 structure revealed the existence of two portals (portal1 and portal2) that lead to its active-site chamber. The DFP-inhibited enzyme underwent the aging process with the negatively charged phosphoryl oxygen, resulting from the loss of an isopropyl group, being within hydrogen-binding distance to the oxyanion hole. The MAFP-inhibited pat17 structure showed that MAFP did not age following its interaction with the nucleophilic serine residue (Ser77) of pat17 since its O-methyl group was intact. The MAFP moiety is oriented with its phosphoryl oxygen in close proximity to the oxyanion hole of pat17 and its O-methyl group located farther away from the oxyanion hole of pat17 relative to the DFP-bound state. The orientation of the alkoxy oxygens within the two OP compounds suggests a role for the oxyanion hole in stabilizing the emerging negative charge on the oxygen during the aging reaction. The arachidonic acid side chain of MAFP could be contained within portals 1 or 2. Comparisons of pat17 in the native, inhibited, and aged states showed no significant global conformational changes with respect to their Cα backbones, consistent with observations from other α/β hydrolases such as group VIIA phospholipase A2

Proposed catalytic mechanism for the active site of Pat17.

<p>Asp215 (not shown) acts as a general base and activates the Ser77 nucleophile by abstracting its terminal hydrogen. The activated Ser77 (shown as –OH) attacks the acyl carbon of the substrate forming a tetrahedral intermediate whose negative charge is shielded by the oxyanion hole of Pat17 (not shown). Loss of R-OH yields an acyl-enzyme intermediate that is hydrolyzed rapidly (passing through another tetrahedral intermediate) to release the acyl moiety and regenerate the enzyme.</p

Pat17 bound to OPs.

<p>Initial difference (<i>F_o-F_c</i>) maps contoured at 3σ (depicted as a green mesh) showing the positive electron densities around (A) the aged DFP and (B) the non-aged MAFP adducts on the catalytic Ser77 residue of pat17. (C and D) The active site of patatin with (C) the aged DFP and (D) non-aged MAFP adducts showing contact distances between the adducts and the oxyanion hole of pat17 as well as the contact distance between the negatively charged oxygen atoms of the aged DFP and the backbone amide nitrogen of Thr78. For clarity, the orientation of the molecule is a 180° rotation about the X- and Y-axes in panel A. (E) 2F_o-F_c electron density (contoured at 1 σ; depicted as a blue mesh) around the catalytic Ser77 residue in complex with MAFP. The active site Ser77 and Asp215 residues as well as the residues that comprise the oxyanion hole of pat17 are rendered as sticks with the following color scheme: yellow  =  carbon, blue  =  nitrogen and red  =  oxygen.</p

Pat17 structure.

<p>(A) The left panel is the overall view of pat17. The protein consists of 8 β-strands and 9 α-helices. The patatin fold is a modified α/β hydrolase fold with a central β-sheet sandwiched by α-helices. The residues that form the oxyanion hole (Gly37, Gly38, Ile39, Arg40 and Gly41) are colored yellow while residues in the active site dyad (Ser77 and Asp215) are shown in magenta. The right panel is a 90° rotation of the left panel about the x-axis depicting the location of the two portals (shown as red arrows) flanking helix 7 (α7) that lead into the active site chamber of the enzyme. (B) Solvent-accessible surface of native pat17 depicting the location of the two portals (denoted via red arrows). Pat17 is shown in the same orientation as the left panel in (A) with Ser77 rendered as yellow spheres. (C) Overlay of pat17 in its native (green), MAFP-inhibited (magenta) and DFP-aged (blue) states showing that there is no significant global conformational change associated with inhibition and aging of an OP compound on the active site serine (Ser77) of the enzyme (denoted as sticks with carbons colored green (native), magenta (MAFP-inhibited) or blue (DFP-aged)). An arrow denotes the active site of pat17. (D) Overlay of average main-chain B-factors for the residues in native, inhibited and aged pat17.</p

Crystallography Data Collection and Refinement Statistics.

1<p> Statistics for highest resolution bin of reflections in parentheses.</p>2<p> R_sym  = S_hS_j l I_hj-h> l/S_hS_jI_hj, where I_hj is the intensity of observation j of reflection h and h> is the mean intensity for multiply recorded reflections.</p>3<p> Intensity signal-to-noise ratio.</p>4<p> Completeness of the unique diffraction data.</p>5<p> R-factor  =  S_h I IF_oI – IF_cI I/S_hIF_oI, where F_o and F_c are the observed and calculated structure factor amplitudes for reflection h.</p>6<p> R_free is calculated against a 10% random sampling of the reflections that were removed before structure refinement.</p>7<p> Root mean square deviation of bond lengths and bond angles.</p>8<p> Number of steric overlaps>0.4 Å per 1000 atoms.</p><p>Crystallography Data Collection and Refinement Statistics.</p

Kinetics of inhibition and aging of DFP and MAFP against Pat17.

1<p> Mean 20-min IC₅₀ ± SEM obtained from 2–4 independent experiments.</p>2<p> Complete reactivation occurred at all time points, thus no aging was observed within the 20-min interval.</p><p>Kinetics of inhibition and aging of DFP and MAFP against Pat17.</p

Structures of (A) DFP and (B) MAFP in their native state as well as the putative structures of these inhibitors in their aged forms.

<p>Chemical structures were generated in MarvinSketch 5.5 (ChemAxon, <a href="http://www.chemaxon.com" target="_blank">http://www.chemaxon.com</a>).</p