Activity-Based Protein Profiling for the Identification of Novel Carbohydrate-Active Enzymes Involved in Xylan Degradation in the Hyperthermophilic Euryarchaeon Thermococcus sp. Strain 2319x1E

Activity-based protein profiling (ABPP) has so far scarcely been applied in Archaea in general and, especially, in extremophilic organisms. We herein isolated a novel Thermococcus strain designated sp. strain 2319x1E derived from the same enrichment culture as the recently reported Thermococcus sp. strain 2319x1. Both strains are able to grow with xylan as the sole carbon and energy source, and for Thermococcus sp. strain 2319x1E (optimal growth at 85°C, pH 6–7), the induction of xylanolytic activity in the presence of xylan was demonstrated. Since the solely sequence-based identification of xylanolytic enzymes is hardly possible, we established a complementary approach by conducting comparative full proteome analysis in combination with ABPP using α- or β-glycosidase selective probes and subsequent mass spectrometry (MS)-based analysis. This complementary proteomics approach in combination with recombinant protein expression and classical enzyme characterization enabled the identification of a novel bifunctional maltose-forming α-amylase and deacetylase (EGDIFPOO_00674) belonging to the GH57 family and a promiscuous β-glycosidase (EGIDFPOO_00532) with β-xylosidase activity. We thereby further substantiated the general applicability of ABPP in archaea and expanded the ABPP repertoire for the identification of glycoside hydrolases in hyperthermophiles.

Simplified Enzymatic Synthesis of 2-Keto-3-Deoxy-D-Gluconate from D-Gluconate Using the Gluconate Dehydratase from Thermoproteus tenax

Many research areas, e.g., basic research but also applied fields of biotechnology, biomedicine, and diagnostics often suffer from the unavailability of metabolic compounds. This is mostly due to missing easy and efficient synthesis procedures. We herein describe the biocatalytic/enzymatic production of 2-keto-3-deoxy-D-gluconate, an intermediate of central metabolic pathways in all three domains of life and also of bacterial polysaccharides, lipopolysaccharides, and cell wall components. The method is based on the gluconate dehydratase from the hyperthermophilic crenarchaeon Thermoproteus tenax, which can be easily recombinantly overproduced in Escherichia coli and-due to its intrinsic thermostability-rapidly be purified by two precipitation steps. The enzyme completely converts D-gluconate to solely stereochemically pure KDG, taking benefits from the enol-keto-tautomerism of the primary reaction product. The final product can then easily be separated from the protein by ultrafiltration. The simple one-step procedure, which is suitable at least for the lab-scale/gram-scale production of KDG, replaces lengthy multi-step reactions and is easily scalable. This approach also illustrates the great application potential of Archaea with their unusual metabolic pathways and enzymes for the synthesis of added value products.

Partial Time-Reversal Invariance Violation in a Flat, Superconducting Microwave Cavity with the Shape of a Chaotic Africa Billiard

We report on the experimental realization of a flat, superconducting microwave resonator, a microwave billiard, with partially violated time-reversal (T) invariance, induced by inserting a ferrite into the cavity and magnetizing it with an external magnetic field perpendicular to the resonator plane. In order to prevent its expulsion caused by the Meissner-Ochsenfeld effect, we used a cavity of which the top and bottom plate were made from niobium, a superconductor of type II, and cooled it down to liquid-helium temperature T_{LHe}≃4  K. The cavity had the shape of a chaotic Africa billiard. Superconductivity rendered possible the accurate determination of complete sequences of the resonance frequencies and of the widths and strengths of the resonances, an indispensable prerequisite for the unambiguous detection of T invariance violation, especially when it is only partially violated. This allows for the first time the precise specification of the size of T invariance violation from the fluctuation properties of the resonance frequencies and from the strength distribution, which actually depends sensitively on it and thus provides a most suitable measure. For this purpose we derived an analytical expression for the latter which is valid for isolated resonances in the range from no T invariance violation to complete violation.

Structural basis for (p)ppGpp-mediated inhibition of the GTPase RbgA

Efficient adaptation to environmental changes is pivotal for all bacterial cells. Almost all bacterial species depend on the conserved stringent response system to prompt timely transcriptional and metabolic responses according to stress conditions and nutrient depletion. The stringent response relies on the stress-dependent synthesis of the second messenger nucleotides and alarmones (p)ppGpp, which pleiotropically target and reprogram processes that consume cellular resources, such as ribosome biogenesis. Here we show that (p)ppGpp acts on the ribosome biogenesis GTPase A (RbgA) of Gram-positive bacteria. Using X-ray crystallography, hydrogen-deuterium exchange MS (HDX-MS) and kinetic analysis, we demonstrate that the alarmones (p)ppGpp bind to RbgA in a manner similar to that of binding by GDP and GTP and thereby act as competitive inhibitors. Our structural analysis of Staphylococcus aureus RbgA bound to ppGpp and pppGpp at 1.8 and 1.65 Å resolution, respectively, suggested that the alarmones (p)ppGpp prevent the active GTPase conformation of RbgA by sterically blocking the association of its G2 motif via their 3'-pyrophosphate moieties. Taken together, our structural and biochemical characterization of RbgA in the context of the alarmone-mediated stringent response reveals how (p)ppGpp affects the function of RbgA and reprograms this GTPase to arrest the ribosomal large subunit.

Spectral Properties of Dirac Billiards at the van Hove Singularities

We study distributions of the ratios of level spacings of rectangular and Africa-shaped superconducting microwave resonators containing circular scatterers on a triangular grid, so-called Dirac billiards (DBs). The high-precision measurements allowed the determination of, respectively, all 1651 and 1823 eigenfrequencies in the first two bands. The resonance densities are similar to that of graphene. They exhibit two sharp peaks at the van Hove singularities which separate the band structure into regions with a linear and a quadratic dispersion relation, respectively. In the vicinity of the van Hove singularities we observe rapid changes in, e.g., the wave function structure. Accordingly, we question whether the spectral properties are there still determined by the shapes of the DBs. The commonly used statistical measures are no longer applicable; however, we demonstrate in this Letter that the ratio distributions provide suitable measures.

Langzeit-Antiaggregation mit Clopidogrel statt ASS, Clopidogrel und ASS

Eine dauerhafte Thrombozytenaggregationshemmung ist ein essenzieller Bestandteil der Sekundärprophylaxe nach akutem Koronarsyndrom (ACS). Seit Ende der 1980er Jahre des vergangenen Jahrhunderts ist die Thrombozytenaggregationshemmung mit Azetylsalizylsäure (ASS) als eine effektive und sichere Therapie für diese Indikation etabliert. Etwa ein Jahrzehnt später wurde mit der Einführung der Thienopyridine eine kombinierte synergistische Thrombozytenaggregationshemmung möglich, die insbesondere in der interventionellen Kardiologie neue Möglichkeiten eröffnete. Das zuerst verfügbare Ticlopidin ist mittlerweile, aufgrund der besseren pharmakologischen Eigenschaften und des günstigeren Profils an unerwünschten Arzneimittelwirkungen durch Clopidogrel weitgehend ersetzt. Nach wie vor hat die Standardtherapie mit ASS in niedriger Dosierung (mindestens 75 mg/d) als Langzeittherapie in der Sekundärprophylaxe einen hohen Stellenwert. Clopidogrel bietet nach den aktuellen Studien jedoch eine ebenso sichere und effektive Alternative. Nach PTCA mit Implantation eines herkömmlichen Metallstents sollte zur Verhinderung einer akuten Stentthrombose für mindestens vier Wochen eine Kombinationstherapie mit ASS und Clopidogrel durchgeführt werden. Bei ACS ohne ST-Strecken-Hebungsinfarkt ist die Kombination von ASS und Clopidogrel besser als die alleinige Gabe von ASS. Aktuelle Daten scheinen dies auch für das ACS mit ST-Strecken-Hebungsinfarkt zu belegen. Ob generell die dauerhafte Kombinationstherapie von ASS mit Clopidogrel zur Sekundärprophylaxe sicher und evtl. effektiver ist, wird diskutiert.

[Inhibition of platelet aggregation for the secondary prevention after ACS: when clopidogrel instead of ASA, when clopidogrel and ASA?]

Long-term inhibition of platelet aggregation is essential for the secondary prevention after acute coronary syndromes (ACS). Inhibition of platelet aggregation with acetylsalicylic acid (ASA) has been established as a safe and effective therapy in this indication already end of the eighties in the preceding century. A decade later, with the introduction of the thieno-pyridines, combined platelet aggregation inhibition became possible. This opened the door for new treatment strategies in interventional cardiology. The first substance, ticlopidine was more or less replaced by the newer substance clopidogrel, which has improved pharmacological properties and less side effects. Low dose ASA (75 mg/d) is still regarded as the standard therapy for secondary prevention after ACS. However, large clinical trials established clopidogrel as at least as effective and safe as ASA in this indication. Following PCI with bare metal stent implantation, a combined therapy of ASA and clopidogrel should be given for at least 4 weeks. After ACS with non-ST-elevation myocardial infarction the combined therapy with ASA and clopidogrel gives a better outcome than ASA alone. Recently published clinical trials show superiority of this strategy in patients with ST-elevation myocardial infarction, too. If a combined long-term platelet aggregation inhibition with ASA and clopidogrel will be safe and more effective for secondary prevention is discussed.

Cytochrome P450 induction by nitrated polycyclic aromatic hydrocarbons, azaarenes, and binary mixtures in fish hepatoma cell line PLHC-1

Nitrated polycyclic aromatic hydrocarbons (NPAHs) and N-heterocyclic aromatic hydrocarbons (azaarenes) are as ubiquitous in the environment as their parent PAH compounds, although occurring at lower concentrations. The toxicological importance of NPAHs and azaarenes is based on their mutagenic and carcinogenic potential. Azaarenes possess a higher solubility and mobility in the environment than PAHs. However, very little is known about the toxicity and cytochrome P450 (CYP)1A induction potencies of NPAHs and azaarenes in fish. Here we report on the cytotoxicities and relative CYP1A induction potencies of 12 NPAHs, 12 azaarenes, and 11 PAHs, determined as neutral red uptake and ethoxyresorufin-O-deethylase (EROD) activity, respectively, in fish hepatoma PLHC-1 cells. Additionally, CYP1A enzyme protein was determined by ELISA for two NPAHs, azaarenes, PAHs, and binary mixtures. Compared with the structurally analogous PAHs, 2-nitronaphthalene, 3-nitrofluoranthene, 2-aza- and 7-azafluoranthene, 1,6-dinitropyrene, benzo[a]acridine and benzo[h]quinoline revealed higher induction potencies, whereas the other compounds showed similar or less activity. The induction potency was highly dependent on the compounds structural properties, reflected by significant correlations between the half-maximal EROD induction (-log EC50) and the molecular descriptors lipophilicity (log Kow) and maximal molecular length (Lmax). Binary mixtures of 6-nitrochrysene + benzo[a]anthracene, 6-nitrochrysene + benzo[a]acridine, and benzo[a]acridine + benzo[a]anthracene showed an additive interaction. The CYP1A induction potencies of NPAHs and azaarenes, demonstrated here for the first time in fish hepatoma cells, suggest that their contribution to the overall CYP1A induction potencies in PAH-contaminated environmental samples have to be taken into account.

Digestion method for silver accumulated in micro-organisms

Silver is accumulated to high concentrations in certain microbial strains. Here a bomb digestion method is proposed, using HNO3 and HCl, for the extraction and digestion of silver and silver compounds from the organic matrix. The method is applicable for the quantitative determination of silver by inductively coupled plasma atomic emission spectroscopy.

Rotational Spectra of the Thiosulfeno Radical, HSS and DSS, between 0.3 and 0.9 THz

The rotational spectra of the HSS and DSS radicals were studied in selected regions between 331 and 883 GHz. The radicals were produced by discharging a gaseous mixture of hydrogen (or deuterium) and hydrogen sulfide in the cell. The observation of the b-type Q-branch and R-branch lines with K(a) = 2-1 and 3-2 for HSS and DSS, respectively, as well as the a-type R-branch lines allowed the improvement and the determination of the molecular constants among them (in MHz) We have reevaluated the harmonic force field of HSS and the ground state average and approximate equilibrium structural parameters. For the latter, we obtained r(HS) = 135.23 pm, r(SS) = 196.03 pm, and angle = 101.74 degrees. These results are compared with those from previous and own quantum chemical calculations as well as with results of related molecules. Copyright 2000 Academic Press.

Akuter Myokardinfarkt – Thrombolyse versus interventionelle Therapie

Die frühe, vollständige und anhaltende Rekanalisation des Infarktgefäßes ist das entscheidende therapeutische Ziel in der Behandlung des akuten Myokardinfarkts. Durch die Einführung der intravenösen Thrombolysetherapie ist die Letalität signifikant gesunken. In prospektiven Studien sind die Thrombolytika Streptokinase und rt-PA umfassend geprüft. Ihr Differentialeinsatz in der Akuttherapie ist heute genau definiert. Das Wissen um die Bedeutung der Thrombozytenaggregation in der Thrombogenese führte zur Untersuchung von Kombinationen moderner GPIIb/IIIa-Inhibitoren mit Plasminogen-Aktivatoren. Als wirksame Alternative zur Thrombolyse hat sich in den letzten Jahren die akute, kathetertechnische Ballondilatation etabliert. In Kombination mit einer Thrombozyteninhibition mit dem monoklonalen Antikörper Abciximab und einer Stentimplantation können exzellente Ergebnisse erzielt werden. Nachteil dieses Vorgehens ist der höhere wirtschaftliche Aufwand sowie die Beschränkung auf entsprechend ausgestattete Zentren. Zukünftige Strategien werden darauf hinzielen, thrombolytische Therapien so zu entwickeln, daß sie sich im Einzelfall optimal durch mechanische Rekanalisationsverfahren ergänzen lassen. Patienten, die besonders von einem solchen kooperativen Konzept zwischen Krankenhäusern der Regelversorgung, Notärzten und interventionell aktiven Zentren profitieren, müssen identifiziert werden.

Silver-based crystalline nanoparticles, microbially fabricated

One mechanism of silver resistance in microorganisms is accumulation of the metal ions in the cell. Here, we report on the phenomenon of biosynthesis of silver-based single crystals with well-defined compositions and shapes, such as equilateral triangles and hexagons, in Pseudomonas stutzeri AG259. The crystals were up to 200 nm in size and were often located at the cell poles. Transmission electron microscopy, quantitative energy-dispersive x-ray analysis, and electron diffraction established that the crystals comprise at least three different types, found both in whole cells and thin sections. These Ag-containing crystals are embedded in the organic matrix of the bacteria. Their possible potential as organic-metal composites in thin film and surface coating technology is discussed.

The ND Radical: Laboratory Measurement of the N = 2-1 Rotational Transition at 1 THz

The N = 2-1 pure rotational transition of the ND radical (X3Sigma-) near 1 THz was measured with the Cologne terahertz spectrometer. The ND radical was produced in a dc discharge of a flowing mixture of deuterated ammonia and helium. Frequencies of five strong fine-structure transitions with associated hyperfine components were precisely measured and analyzed to determine a complete set of accurate molecular constants, e.g., the rotational and centrifugal distortion constants B0 = 263265.4735(45) MHz and D0 = 14.62876(74) MHz, together with the fine and hyperfine constants. Based on these constants, the rotational frequencies of ND up to 4 THz were predicted with the aim to guide future astronomical searches. For completeness we also include similar predictions for NH. Copyright 1998 Academic Press.

Precise Measurement of the Pure Rotational Submillimeter-Wave Spectrum of HCl and DCl in Their v = 0, 1 States

High-resolution sub-Doppler Lamb-dip measurements were performed on the low-J pure rotational transitions of the hydrogen chloride isotopomers H35Cl, H37Cl, D35Cl, and D37Cl in the submillimeter-wave region up to 646 GHz. For the J = 1-0 transitions of the two HCl isotopomers, the hyperfine splitting due to the hydrogen nuclear spin-rotation interaction is resolved. Furthermore Doppler-limited lines of the DCl J = 3 <-- 2 transition around 965 GHz as well as hyperfine-resolved rotational transitions in the first excited vibrational state were recorded up to 1.22 THz. The new frequencies were analyzed in a global fit together with FIR data yielding a set of mass-invariant rotational parameters. Isotopically invariant hyperfine parameters were obtained also from the global fit. Inclusion of the precise results from molecular beam electric resonance measurements allowed the determination of higher orders of the vibrational and rotational expansion coefficients of the chlorine and hydrogen hyperfine interactions. The precise transition frequencies reported here should be useful as secondary calibration standards in the submillimeter-wave and terahertz region. Copyright 1998 Academic Press. Copyright 1998Academic Press

Submillimeter-Wave Rotational Spectra of SO Isotopomers in the Electronic States a1Delta and b1Sigma+

Pure rotational transitions of the sulfur monoxide isotopomers 32S16O, 34S16O, and 32S18O were measured in different vibrational states of the electronic states a1Delta and b1Sigma+ with the Cologne terahertz spectrometer in the submillimeter-wave region between 300 and 1070 GHz. The new lines were analyzed together with previous results from the literature in a global fit yielding isotopically invariant rotational parameters for both states. The measurements reported here allowed for the first time the determination of the parameters U01S and U01O to correct for the breakdown of the Born-Oppenheimer approximation analogously to the X3Sigma- state. Precise equilibrium bond lengths re are given for all states concerned. Copyright 1997 Academic Press. Copyright 1997Academic Press

Pure Rotational Spectra of SO: Rare Isotopomers in the 80-GHz to 1.1-THz Region

Pure rotational spectra of rare isotopomers of sulfur monoxide, SO, have been recorded with the Cologne Terahertz Spectrometer, Germany, and the millimeter- and submillimeter-wave spectrometer at Nobeyama, Japan. In total, 176 new transitions have been measured in the X3Sigma- electronic ground state, including the first laboratory detection of the rare isotopomer 36SO. New lines are also reported for 33SO and S17O in their vibrational ground states, and for 33SO and S18O in the first excited vibrational state. A simultaneous fit of 451 transitions has led to an improved set of isotopically invariant parameters for rotation and fine structure. Hyperfine structure constants for 33SO and S17O have been obtained also from the global fit, including first values for the magnetic nuclear spin-rotation interaction. These are compared to other molecules. The isotopically invariant parameters allow precise frequency predictions for the submillimeter-wave region far beyond 1 THz for all SO isotopomers, of importance to astrophysical applica- tions.

Increased lymphocytic Na+/H+ exchange activity after hemodialysis: evidence for an endogenous inhibitor of Na+/H+ exchange in patients with end-stage renal failure

The Na+/H+ exchange antiport activity was measured in lymphocytes from 16 patients with end-stage renal failure pre- and postdialysis. In addition the effect of the patients' plasma on lymphocytes from healthy subjects was tested. Resting pH (pHi) was not significantly different in lymphocytes pre- and postdialysis. On the other hand, the Na+/H+ exchange activity was significantly lower in lymphocytes before hemodialysis (6.22 +/- 0.73 x 10(-3) pHi/s) than after hemodialysis (9.32 +/- 1.58 x 10(-3) pHi/s; n = 16; p < 0.05). The buffer capacity was not significantly different before and after hemodialysis. The incubation of lymphocytes from healthy control subjects with plasma from patients with end-stage chronic renal failure significantly reduced the lymphocytic Na+/H+ exchange activity. The addition of ultrafiltrate also significantly reduced the Na+/H+ exchange activity in lymphocytes from healthy control subjects. The study indicates the existence of an endogenous inhibitor of the Na+/H+ exchange that is accumulated in plasma from patients with end-stage chronic renal failure.

Lymphocytic Na(+)-H+ exchange increases after an oral glucose challenge

The effects of oral glucose challenge on plasma glucose concentration, plasma insulin concentration, arterial blood pressure, cytosolic pH (pHi), cytosolic free Na+ concentration ([Na+]i), and cellular Na(+)-H+ exchange activity were investigated in 16 healthy subjects. The pHi, [Na+]i, and Na(+)-H+ exchange activity were measured in intact lymphocytes by using the fluorescent dye technique. The oral glucose challenge significantly increased plasma glucose, plasma insulin, and the lymphocytic Na(+)-H+ exchange activity, measured as change of pHi per second (control [0 hours], 5.20 +/- 0.53 x 10(-3) dpHi/s; 1 hour after glucose administration, 8.28 +/- 1.07 x 10(-3) dpHi/s; 2 hours after glucose administration, 8.15 +/- 1.18 x 10(-3) dpHi/s; P = .002). The lymphocytic Na(+)-H+ exchange was significantly correlated with plasma glucose concentration (r = .357, P = .041). During steady state euglycemic hyperinsulinemic clamp, the Na(+)-H+ exchange activity was not significantly changed compared with baseline values. The study shows that changes of blood glucose levels can induce an acute increase in Na(+)-H+ exchange activity. Systolic blood pressure and Na(+)-H+ exchange activity were significantly (P < .001) but weakly correlated during an oral glucose challenge.

Reduced sodium-proton exchange activity in lymphocytes from transgenic rats

We investigated sodium-proton (Na(+)-H+) exchange activity in transgenic TGR(mRen-2)27 rats, a strain showing fulminant hypertension after the mouse Ren-2d renin gene has been integrated into its genome, in age-matched normotensive Sprague-Dawley (SD) rats, in spontaneously hypertensive rats (SHR) from the Münster strain, and in normotensive Wistar-Kyoto (WKY) rats. From each strain Na(+)-H+ exchange activity was determined in lymphocytes using the pH-sensitive fluorescent dye 2',7'-bis(2-carboxyethyl)-5(6)-carboxyfluorescein acetoxymethyl ester (BCECF-AM) by measuring the recovery rate of cytosolic pH (pHi) after intracellular acidification. Resting pHi was not significantly different in transgenic rats (n = 10) compared with SD rats (n = 10) (7.305 +/- 0.038 versus 7.337 +/- 0.031; mean +/- SEM), but resting pHi was significantly lower in lymphocytes from SHR (n = 12) compared with their normotensive WKY counterparts (n = 12) (7.232 +/- 0.030 versus 7.377 +/- 0.022; P < .01). Na(+)-H+ exchange activity was significantly lower in lymphocytes from transgenic rats compared with SD rats (5.102 +/- 0.561 versus 7.385 +/- 0.491 x 10(-3) dpHi/s; P < .01), whereas Na(+)-H+ exchange was significantly enhanced in lymphocytes from SHR compared with WKY rats (5.564 +/- 0.432 versus 3.921 +/- 0.433 x 10(-3) dpHi/s; P < .05). The apparent half-maximal activation of Na(+)-H+ exchange was not significantly different in the strains tested. The present study indicates that hypertension in transgenic rats is not related to Na(+)-H+ exchange overactivity.

[The solubility of drugs in lipoid vehicles]

A method for determination of drug substances solubility in lipophilic solvents is presented. The solubility was determined in lipophilic suppository bases meltings, in pharmaceutical lipoids as Oleum Ricini, Oleum Arachidis, Cera perliquida, Paraffinum perliquidum and in chemically defined lipoids as n-hexadecane, 1-hexadecane, cetylic alcohol, palmitic acid, cetylpalmitate. Consequences from chemical constitution of substances for solubility are discussed, also consequences from chemical constitution and dielectric constants of lipoidic solvents for their solution behavior. For the substances investigated, the apparent partition coefficients in the two-phase systems lipoid/phosphate buffer pH 7,4 and n-octanol/phosphate buffer pH 7,4 were determined, also the solubility in phosphate buffer. The results show, that connections between partition coefficients and solubility in lipophilic or aqueous phases do not exist. On the other hand, an indirect proportionality between water solubility and lipoid solubility also does not exist. In consequence, interpretations of drug release from lipophilic systems have to be proceeded from exact knowledge of partition behavior and solubilities in both the lipophilic and aqueous phase.

[The solubility of drugs in molten suppository bases]

Solubility of 18 drugs used in rectal therapy in molten suppository base, (Massa suppositoriorum 15, Pharmacopeia of the G.D.R. Rosupol U, 37 degrees C) is determined. Separation of drug-saturated base from drug cristals is carried out in an air-heated centrifuge followed by a partition step between petroleum ether and an aqueous medium and photometrical determination of drug concentration. The procedure leads to results with relative standard deviation of 2% (medium value of 18 drugs). The investigation gave solubility values in the range between 0.002% (theobromine) and 26% (lidocaine), whereas benzoate, phenobarbital sodium and procaine hydrochloride are completely insoluble. Sodium salicylate has an unexpected high solubility (0.48%). The solubility is temperature depended and thus the solubility enthalpy can be determined. Relations between structure and solubility are discussed for pyrazolin-5-ones and purines. A correlation between solubilities in the base and in aqueous buffer (phosphate, pH 7.4) does not exist in the series studied.