Structure and Mechanism of an Aspartimide‐Dependent Peptide Ligase in Human Legumain

Peptide ligases expand the repertoire of genetically encoded protein architectures by synthesizing new peptide bonds, energetically driven by ATP or NTPs. Here, we report the discovery of a genuine ligase activity in human legumain (AEP) which has important roles in immunity and tumor progression that were believed to be due to its established cysteine protease activity. Defying dogma, the ligase reaction is independent of the catalytic cysteine but exploits an endogenous energy reservoir that results from the conversion of a conserved aspartate to a metastable aspartimide. Legumain’s dual protease–ligase activities are pH‐ and thus localization controlled, dominating at acidic and neutral pH, respectively. Their relevance includes reversible on–off switching of cystatin inhibitors and enzyme (in)activation, and may affect the generation of three‐dimensional MHC epitopes. The aspartate–aspartimide (succinimide) pair represents a new paradigm of coupling endergonic reactions in ATP‐scarce environments.     

Die Kristallstrukturen von ZrSi und ZrSi2

Zusammenfassung Im System Zr–Si wurde die noch unbekannte Struktur von ZrSi bestimmt. Diese Phase kristallisiert orthorhombisch mit folgenden Gitterkonstanten:a=6,69₈,b=3,77₈ undc=5,29₁ kX·E; sie ist isotyp mit USi bzw. FeB.Auf Grund von Einkristallaufnahmen wurde eine neue Parameterbestimmung für ZrSi₂ durchgeführt. Mit den Werten:y _Zr=0,104,y _{Si I}=0,439 undy _{Si II}=0,750 können die Intensitäten der (0k0-Interferenzen bis zum Reflex (0 36 0) einwandfrei wiedergegeben werden. Der vonNaray-Szabo angegebene Aufbau, in welchem der Charakter eines Schichtengitters zum Ausdruck kommt, wird dadurch merklich modifiziert. Einen derartigen, mit unserem übereinstimmenden Strukturvorschlag haben in der Zwischenzeit auchG. Brauer undH. Haag gefunden.Mit 3 Abbildungen.     

Das Verhalten metallreicher,hochschmelzender Silizide gegenüber Bor,Kohlenstoff, Stickstoff und Sauerstoff

Ohne ZusammenfassungMit 11 AbbildungenHerrn Prof. Dr.E. Schmid zum 60. Geburtstag ergebenst zugeeignet.     

Antibakterielle wirkstoffe. VIII . Die aminomethinylierung in der reihe der aminothiazole

The three-component reaction comprising the interaction of 2-amino-4-antipyrinyl-5-ethylthiazole (1) with s-triazine (2) and pyrrolidine leads to 4-anitpyrinyl-5-ethyl-2-[(4-pyrrolidinyl)methyleneamino]thiazole (5). Structure 5 is supported by ¹H- and ¹³C-NMR spectroscopy.     

Über die Sulfurierung von Thionaphthen und Methylthionaphthenen

Zusammenfassung Die Sulfurierung des Thionaphthens, des 2-Methyl-, 3-Methyl-, 5-Methyl- und des 2,3-Dimethylthionaphthens, die Herstellung der entsprechenden Sulfosäurechloride,-amide und-anilide, die Ermittlung der Stellung des Sulfosäurerestes am Thionaphthenringsystem und die Wiederabspaltung der SO₃H-Gruppe wird beschrieben.     

Characterization of a covalent triazine-humic acid conjugate by gas chromatography

The aim of the described method was the characterization of a “atrazine-mercaptopropionic acid” humic acid conjugate, which was required for the calibration of immunoassays to determine bound residues. In order to estimate the amount of bound triazine, an oxidative nucleophilic substitution reaction of the covalently linked “atrazine-mercaptopropionic acid” to a new triazine derivative “atrazine-methoxyethanol” was performed. This cleavage product was quantified by gas chromatography. The conditions for this cleavage procedure were optimized and applied to the “atrazine-mercaptopropionic acid” humic acid conjugate and to a humic acid blank. The amount of bound “atrazine-mercaptopropionic acid” was calculated to 16.6 ± 2.5 μmol triazine per gram humic acid, which is equivalent to 0.39 ± 0.07% atrazine. Received: 7 August 1997 / Accepted: 12 September 1997     

Continuity of Drag and Domain Stability in the Low Mach Number Limits

We consider a mathematical model of a rigid body immersed in a viscous, compressible fluid moving with a velocity prescribed on the boundary of a large channel containing the body. We assume that the Mach number is proportional to a small parameter ε and that the general boundary of the body contains small asperities of amplitude proportional to ε ^α for a certain α?>?0 and suppose the Navier’s slip condition on this rough boundary. We show that time averages of the drag functional converge, as ε → 0, to the corresponding time averages of the drag for the limit system, whereas the limit system is turning out to be the incompressible Navier–Stokes system with no-slip condition on the smooth limit body.     

Experimental and theoretical investigation of vibrational spectra of copper phthalocyanine: polarized single‐crystal Raman spectra,isotope effect and DFT calculations

The IR‐ and Raman spectra of copper phthalocyanine (CuPc), as well as the isotopic wavenumber shifts upon ¹⁵N substitution in CuPc, were investigated experimentally and theoretically. The symmetry of molecular vibrations was determined using polarized Raman spectra of an oriented CuPc single crystal. Density functional theory (DFT) calculations were used for the detailed assignment of different bands in the vibrational spectra of CuPc. Theoretically predicted geometry, wavenumbers and isotopic shifts are in a very good agreement with the experimental values. A comparison of experimentally obtained isotopic shifts with theoretical predictions allowed us to reveal some characteristic features of normal vibrations of CuPc molecule. Copyright © 2009 John Wiley & Sons, Ltd.     

Optimal Microstructures Drag Reducing Mechanism of Riblets

We consider an optimal shape design problem of periodically distributed three-dimensional microstructures on surfaces of swimming bodies in order to reduce their drag. Our model is restricted to the flow in the viscous sublayer of the boundary layer of a turbulent flow. The costs for the optimization problem are very high because the three-dimensional flow equations have to be solved several times. We avoid this problem by approximations: the microscopic optimization problem is reduced applying homogenization. Considering a special geometry (riblets) the resulting so-called macroscopic optimization problem can be additionally reduced to a two-dimensional problem. We analyze the drag reducing mechanism of riblets which are believed to be optimal structures. Therefore we perform direct simulations on the total rough channel for different shapes of microstructures: riblets and fully three-dimensional structures.