V-type nerve agents phosphonylate ubiquitin at biologically relevant lysine residues and induce intramolecular cyclization by an isopeptide bond

Toxic organophosphorus compounds (e.g., pesticides and nerve agents) are known to react with nucleophilic side chains of different amino acids (phosphylation), thus forming adducts with endogenous proteins. Most often binding to serine, tyrosine, or threonine residues is described as being of relevance for toxicological effects (e.g., acetylcholinesterase and neuropathy target esterase) or as biomarkers for post-exposure analysis (verification, e.g., albumin and butyrylcholinesterase). Accordingly, identification of novel protein targets might be beneficial for a better understanding of the toxicology of these compounds, revealing new bioanalytical verification tools, and improving knowledge on chemical reactivity. In the present study, we investigated the reaction of ubiquitin (Ub) with the V-type nerve agents Chinese VX, Russian VX, and VX in vitro. Ub is a ubiquitous protein with a mass of 8564.8 Da present in the extra- and intracellular space that plays an important physiological role in several essential processes (e.g., proteasomal degradation, DNA repair, protein turnover, and endocytosis). Reaction products were analyzed by matrix-assisted laser desorption/ionization-time-of-flight- mass spectrometry (MALDI-TOF MS) and μ-high-performance liquid chromatography online coupled to UV-detection and electrospray ionization MS (μHPLC-UV/ESI MS). Our results originally document that a complex mixture of at least mono-, di, and triphosphonylated Ub adducts was produced. Surprisingly, peptide mass fingerprint analysis in combination with MALDI and ESI MS/MS revealed that phosphonylation occurred with high selectivity in at least 6 of 7 surface-exposed lysine residues that are essential for the biological function of Ub. These reaction products were found not to age. In addition, we herein report for the first time that phosphonylation induced intramolecular cyclization by formation of an isopeptide bond between the ε-amino group of a formerly phosphonylated lysine and the side chain of an adjacent acidic glutamic acid residue.

Comparison of HPLC Versus HPTLC-Densitometry for the Quantification of Chromone Glucosides in Saposhnikoviae divaricatae Radix

A HPLC and a HPTLC-densitometric method were developed for the quantification of prim-O-glucosylcimifugin and 4′-O-β-d-glucosyl-5-O-methylvisamminol the major chromone glucosides in the roots of Saposhnikovia divaricata. The validation of both methods resulted in comparable parameters regarding stability, specificity, linearity, robustness, precision and recovery, whereas complementary advantages were obtained concerning LOD and LOQ. The HPTLC-based densitometry revealed a lower LOD (1.11 versus 4.37 μg mL⁻¹ in HPLC) and LOQ (3.36 versus 13.24 μg mL⁻¹ in HPLC) for prim-O-glucosylcimifugin, whereas the HPLC resulted in a lower LOD (1.00 versus 4.10 μg mL⁻¹ in HPTLC-densitometry) and LOQ (3.04 versus 12.46 μg mL⁻¹ in HPTLC-densitometry) for 4′-O-β-d-glucosyl-5-O-methylvisamminol. Both methods revealed nearly matching contents of the chromones after analysis of different commercially available batches of Saposhnikoviae divaricatae radix with a total content for both chromone glycosides in the range from 0.31 ± 0.011 to 0.56 ± 0.021 % determined by HPLC and between 0.34 ± 0.011 and 0.61 ± 0.009 % determined by HPTLC. The plant material cultivated in Germany showed a very similar content and ratio of both chromone glucosides in comparison to the standard batches originating from China.

     

Fixpunktklassen

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Über die Konstitution des α-Pyrokresols

Ohne ZusammenfassungZum Schlusse erfülle ich noch die angenehme Pflicht, Herrn Prof. Goldschmiedt für das stets fördernde Interesse, das er meiner Arbeit angedeihen ließ, meinen herzlichsten Dank abzustatten.     

Zur ersten Randwertaufgabe bei Monge-Ampèreschen Differentialgleichungen vom elliptischen Typus; differentialgeometrische Anwendungen

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Ueber Discriminanten und Resultanten der Gleichungen für die Singularitäten der ebenen algebraischen Curven

Ohne ZusammenfassungVgl. die vorläufige Mittheilung in den Göttinger Nachrichten 1888 Nr. 5.     

An added-mass free semi-implicit coupling scheme for fluid–structure interaction

In this Note we propose a semi-implicit coupling scheme for the numerical simulation of fluid–structure interaction systems involving a viscous incompressible fluid. The scheme is stable irrespectively of the so-called added-mass effect and allows for conservative time-stepping within the structure. The efficiency of the scheme is based on the explicit splitting of the viscous effects and geometrical/convective non-linearities, through the use of the Chorin–Temam projection scheme within the fluid. Stability relies on the implicit treatment of the pressure stresses and on the Nitsche's treatment of the viscous coupling. To cite this article: M. Astorino et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009).     

Über Discriminanten und Resultanten der Gleichungen für Singularitäten von algebraischen Raumcurven,mit Anwendungen auf Realitätsverhältnisse

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