Nachweisgrenzen proteolytischer Aktivitäten

Zusammenfassung Verschiedene Methoden der Bestimmung von Proteaseaktivitäten warden jeweils am gleichen Protease-Präparat (Bromelin, Trypsin,-Chymotrypsin, Pepsin) geprüft, um die Erfassungsgrenzen zu ermitteln. Wie erwartet, erhöhen längere Inkubationszeiten die Empfindlichkeit der Methoden, jedoch können auch schon bei Inkubationszeiten von nur 1 Minute beispielsweise noch Trypsinkonzentrationen von ca. 100 ng/ml gemessen werden. Unerwartet war das Ergebnis, daß sich auch mit relativ einfachen Mitteln (Milch als Substrat, Messung der freigesetzten Aminogruppen mit TNBS) noch sehr geringe Enzymkonzentrationen erfassen lassen. Da diese Methode praktisch für alle untersuchten Proteasen von optimaler Empfindlichkeit ist, dürfte sie insbesondere für die Untersuchung von Proteasen unbekannter Natur von Bedeutung sein.

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Detection limits for proteases

Summary Different methods for the assay of protease activities are compared with the same protease preparation (bromelin, trypsin, -chymotrypsin, pepsin) in order to find out the limits of detection. As expected the sensitivity of the methods rises with the longer incubation times, but in spite of this incubations as short as 1 minute may be sufficient in the determination of e. g. trypsin at a level of 100 ng/ml. Unexpected was the result that with a rather simple method (milk as substrate, determination of free amino groups with trinitrobenzenesulfonic acid) very small concentrations of enzyme may be measured. As this method practically gives optimal sensitivity for all proteases studied, it may be of special value for the assay of proteases whose nature is unknown.

     

13C-NMR-spektroskopische und stereochemische Untersuchungen: XI—Konformationen von Bicyclo[3.3.1]nonanen und ihre Unterscheidbarkeit durch lanthanideninduzierte Verschiebungen

The ¹³C chemical shifts of bicyclo[3.3.1]nonane and of the corresponding 9-hydroxy- and 9-oxo- derivatives are compared with chemical shifts calculated on the basis of stereospecific shift increments. These results as well as the ¹H n.m.r. spectrum of the ketone indicate a predominant chair-chair conformation CC. A low temperature ¹³C n.m.r. study as well as an analysis of the temperature dependence of ¹³C chemical shifts in bicyclo[3.3.1]nonane furnish a limit for the free energy difference between CC and BC conformations of ΔG ≧ 5,85 kJ mol^?1. The distinction between CC, BC and BB provides a test for the applicability of lanthanide-induced ¹H and ¹³C shifts for the assignment of flexible geometries. The typical occurrence of several and/or flat minima in the LIS geometry analysis allows only the exclusion of boat–boat conformations.     

Conformal changes of metrics and the initial-value problem of general relativity

Conformal techniques are reviewed with respect to applications to the initial-value problem of general relativity. Invariant transverse traceless decompositions of tensors, one of its main tools, are related to representations of the group of conformeomorphisms acting on the space of all Riemannian metrics onM. Conformal vector fields, a kernel in the decomposition, are analyzed on compact manifolds with constant scalar curvature. The realization of arbitrary functions as scalar curvature of conformally equivalent metrics, a generalization of Yamabe's conjecture, is applied to the Hamiltonian constraint and to the issue of positive energy of gravitational fields. Various approaches to the solution of the initial-value equations produced by altering the scaling behavior of the second fundamental form are compared.     

The eightfold way to color geometrodynamics

Color models of strong interactions are generalized to aGL(8,) ^f GL(8,) ^c gauge theory incorporating space-time curvature and Cartan's torsion. Following Salam, the dynamics is determined by an Einstein-Dirac-type Lagrangian. The resulting field equations are anonlinear (due to the torsion) Heisenberg-Pauli-Weyl equation for the fundamental spinor fields and a generalized Einstein equation for the background metric of hadronic dimensions. According to this model baryonic quarks are confined ingeon (black soliton)-type objects by the tensor gluons ofstrong gravity. This approach also leads to a black soliton mass formula which is in qualitative agreement with part of the baryon spectrum. Hadronic mesons are interpreted as gluon strings trapped in a multiconnected space-time. Interrelations of color geometrodynamics with other bag models are pointed out. Finally, the conceptual origin of this space-time foundation of quark confinement is presented.     

Dark matter problem and effective curvature Lagrangians

A ‘radical’ conservative unifying model of scalar dark matter and modified gravity is proposed here. After a conformal mapping, the dependence of the effective Lagrangian on the curvature is not only singular but also bifurcates into several almost Einsteinian spaces, distinguished only by a different gravitational strength and cosmological constant. A swallow tail or butterfly catastrophe in the bifurcation set indicates the possibility for the coexistence of different Einsteinian domains in our Universe. This finding may shed new light on the nature and large scale distribution not only of dark matter but also on ‘dark energy’, regarded as an effective cosmological constant.     

Progress in metric-affine gauge theories of gravity with local scale invariance

Einstein's general relativity theory describes very well the gravitational phenomena in themacroscopic world. In themicroscopic domain of elementary particles, however, it does not exhibit gauge invariance or approximate Bjorken type scaling, properties which are believed to be indispensible for arenormalizable field theory. We argue that thelocal extension of space-time symmetries, such as of Lorentz and scale invariance, provides the clue for improvement. Eventually, this leads to aGL(4, R)-gauge approach to gravity in which the metric and the affine connection acquire the status ofindependent fields. The Yang-Mills type field equations, the Noether identities, and conformal models of gravity are discussed within this framework. After symmetry breaking, Einstein's GR surfaces as an effective low-energy theory.Based on a plenary talk given by one of us (EWM) at the 53rd annual meeting of the Deutsche Physikalische Gesellschaft in Bonn on March 14, 1989.Supported by the German-Israeli Foundation for Scientific Research and Development (GIF), Jerusalem and Munich.Supported by the Deutsche Forschungsgemeinschaft (DFG), Bonn, project He 528/12-1.Supported in part by DOE Grant DE-FG05-85-ER40200.     

Notes on a Recent Paper About the Cleavage of N,N-Dimethylhydrazones and Tosylhydrazones

The reaction of dimethylhydrazones with dimethyl sulfate and potassium carbonate gives the N,N,N-trimethyl methylsulfate (e.g. 3a) primarily which may be hydrolyzed to the ketone subsequently. Tosylhydrazones give the N-methyl derivatives only and not the related ketones. Deviating results by A. Kamal et al. cannot be reproduced.