On strong summability of multiple Fourier series and smoothness properties of functions

_n —n- — ƒ()L _v (T _n ), 1f, - -. -.     

Zur Synthese von Human-Big-Gastrin I

The synthesis of the tetratriacontapeptide amide corresponding to the revised primary structure of human big gastrin I is described. For this purpose the fragments were designed in view of the maximum use of those utilized in our previous synthesis of human big gastrin I according to the first sequence proposal. Consequently the key tripeptide-Pro-Pro-His- (sequence 7–9) was prepared in suitably protected form to be used as amino or carboxyl component for assembly of the segments 1–9 and 1–14, respectively. Final condensation of the latter nona- and tetradecapeptide derivatives with the C-terminal segments 10–34 and 15–34 via the azide and the dicyclohexylcarbodiimide/N-hydroxysuccinimide procedure, respectively, leads to crude fully protected human big gastrin I. Upon deprotection by exposure to trifluoroacetic acid in presence of ethanedithiol-(1,2) as scavanger, ion exchange chromatography and partition chromatography, the desired tetratriacontapeptide amide was isolated in satisfactory yield with a high degree of purity. The identical immunological behaviour of the synthetic material, if compared with that of natural human big gastrin I, represents ulterior strong evidence for the correctness of the newly proposed structure for this putative prohormonal form of the gastrins.

Kurzmitteilung:Wünsch E., Wendlberger G., Mladenova-Orlinova L., Göhring W., Jaeger E., Scharf R., Gregory R. A., Dockray G. J., Hoppe-Seyler's Z. Physiol. Chem.362, 179 (1981).     

Lac repressor

Repressors are proteins that interact with inducers and operators to regulate the synthesis of enzymes in the cell. Lac repressor ensures that sufficient β-galactosidase is available to the bacterium Escherichia coli, depending upon the amount of lactose present in the culture medium. It has proved possible to isolate lac repressor from E.coli. The present progress report describes how these discoveries were made, as well as the formation and mode of action of the repressor.     

Study of the thermal oxidation of polyolefines—II: Effect of layer thickness on the rate of oxidation in the melt phase

A study was made of the kinetics of oxygen absorption and isothermal weight change as a function of layer thickness for molten polyethylene at 157° under oxygen at 650 torr pressure. The effect of the rate of transport processes on the rate of thermal oxidation was found to be conversion dependent.Comparison of the experimental data on the effect of layer thickness on the maximum rate of oxygen absorption with the results of calculations (carried out assuming various overall reaction orders and applying literature data on permeability coefficient) suggests that, during degradation, the reaction rate is affected by the opposed transport processes of oxygen and the volatile decomposition products. The weight change, closely related to the transport process of volatile products, is diffusion-controlled over the whole range of thickness studied. At the same time, below a critical thickness (approx. 0·05 mm), even the maximum rate of oxygen consumption may be considered a function of only the kinetic parameters.     

Molybdän(VI) -Hydroxylamin- Komplexe. IV

Zusammenfassung 4-(2-Pyridylazo)-resorcin (PAR) bildet mit sechswertigem Molybdän und Hydroxylamin einen ternären, rot gefärbten Komplex. Dieser enthält die Komponenten in einem molaren Verhältnis 111. Die Bildung dieses Komplexes ist die Grundlage für eine sehr empfindliche spektralphotometrische Molybdänbestimmung. Die Kennziffern für diese Reaktion werden angegeben. Störende Fremdmetalle können durch DCTA und Weinsäure maskiert oder durch Extraktion ihrer PAN-Komplexe mit Chloroform abgetrennt werden. Wolfram bildet keinen gefärbten Komplex mit PAR.

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Molybdenum-hydroxylamine complexes. IV

Summary A ternary red complex results from the action of 4-(2-pyridylazo)-resorcinol (PAR) with hexavalent molybdenum and hydroxylamine. This product contains the components in a molar ratio 111. The formation of this complex is the basis for a very sensitive spectrophotometric determination of molybdenum. The characteristics of this reaction are stated. Interfering foreign ions can be masked by DCTA and tartaric acid or removed by extraction of its PAN-complex with chloroform. Tungsten does not yield a colored complex with PAR.

     

Spektrographische Bestimmung von Verunreinigungen im reinen Kupfer mit dem Kugelbogen unter Sauerstoffatmosph?re

Zusammenfassung Zur spektrochemischen Spurenbestimmung im reinen Kupfer mit dem Kugelbogen wird eine Entladungsküvette vorgestellt, die auch für andere analytische Reinststoffprobleme einzusetzen ist. Die entwickelte Küvette besteht im Prinzip aus einem dreiteiligen Glaskörper, in dem die Anregung unter Reaktions- oder Inertgas erfolgen kann. Die Küvette wird am Funkenstativ einfach gehaltert und justiert.Nach der gegebenen Arbeitsvorschrift können die Elemente Silber, Blei, Zinn, Antimon, Wismut, Eisen und Nickel im reinen Kupfer quantitativ bis zu ppm-Gehalten unter Sauerstoffatmosphäre erfaßt werden. Die ermittelten Garantiegrenzen für Reinheit gewähren die Kennzeichnung eines 5 N Kupfers.

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Spectrographic determination of impurities in pure copper by means of the globule arc in oxygen atmosphere

For the spectrochemical determination of trace elements in pure copper by means of the globule arc, a chamber for controlled atmosphere is described, which is to be used also for solving other analytical problems of high-purity materials. Principally, the chamber is a glass body consisting of three parts, in which the excitation may be performed in reaction or inert gases. The chamber can easily be mounted and adjusted on the spark stand.According to the given method traces of silver, lead, tin, antimony, bismuth, iron and nickel can quantitatively be determined in an oxygen atmosphere down to ppm quantities. The calculated limits guaranteed as to purity give the possibility of characterizing a copper of 5 nines quality.

     

Electrophoretic separation of carrier-free radionuclides

The electrophoretic separation of radioactive rare earths on Cellogel in α-hydroxyisobutyric acid is described. Minute amounts of radioactive daughter nuclides are separated from the neutron-irradiated rare earth target materials, the ratio of the substances being 10⁵∶1 to 10⁷∶1. The suggested method is simple, rapid and suitable for analytical purposes.     

Structures and spectra of Na(NH3) n=1,2

Geometric structures and the energies for the ground and several excited electronic states of a sodium atom bound with one or two ammonia molecules are presented. All self consistent field (SCF) calculations are performed with extended basis sets. Geometry optimization and one electron properties have been performed within the SCF approximation. Excited states have been calculated with the multi-configuration SCF (MCSCF) technique. This system may be viewed as a precursor to solvation in a macroscopic system. The excited state calculations provide important information for spectroscopic studies of these complexes.     

Identification of dinucleoside polyphosphates by matrix-assisted laser desorption/ionisation post-source decay mass spectrometry

Dinucleoside polyphosphates are a group of intra- and extracellular mediators controlling numerous physiological functions. In this study dinucleoside polyphosphates were examined by positive ion matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry (MADLI-TOFMS). 3-Hydroxypicolinic acid was used as UV-absorbing matrix. For the individual dinucleoside polyphosphates Ap(n)A (n = 2-7), Ap(n)G (n = 2-6) and Gp(n)G (n = 2-6), MALDI post-source decay (PSD) mass spectra were measured. Each mass peak in the MALDI-PSD mass spectra could be assigned to individual fragments of dinucleoside polyphosphates. The comparison of the fragmentation patterns of the dinucleoside polyphosphates presented here demonstrates that dinucleoside polyphosphates preferably cleave to fragment ions consisting of the corresponding mononucleoside polyphosphates as well as the corresponding nucleosides and bases during flight in the field-free drift path of the MALDI mass spectrometer. Therefore, the MALDI-PSD approach described here is suitable for identification of other dinucleoside polyphosphates. The present MALDI-PSD mass spectra may be used as MALDI-PSD mass reference spectra for future identification of dinucleoside polyphosphates and other nucleotides.     

How does product isotope effect prove the operation of a two-state "rebound" mechanism in C-H hydroxylation by cytochrome P450?

C-H hydroxylation is a fundamental process. In Nature it is catalyzed by the enzyme cytochrome P450, in a still-debated mechanism that poses a major intellectual challenge for both experiment and theory; currently, the opinions keep swaying between the original single-state rebound mechanism, a two-oxidant mechanism (where ferric peroxide participates as a second oxidant, in addition to the primary active species, the high-valent iron-oxo species), and two-state reactivity (TSR) mechanism (where two spin states are involved). Recent product isotope effect (PIE) measurements for the trans-2-phenyl-methyl cyclopropane probe (1), led Newcomb and co-workers (Newcomb, M.; Aebisher, D.; Shen, R.; Esala, R.; Chandrasena, P.; Hollenberg, P.; Coon, M. J. J. Am. Chem. Soc. 2003, 125, 6064-6065) to rule out TSR in favor of the two-oxidant scenario, since the direction of the PIE was at odds with the one predicted from calculations on methane hydroxylation. The present report describes a density functional theoretical study of C-H hydroxylation of the Newcomb probe, 1, leading to rearranged (3) and unrearranged (2) products. Our study shows that the reaction occurs via TSR in which the high-spin pathway gives dominant rearranged products, whereas the low-spin pathway favors unrearranged products. The calculated PIE(2/3) values based on TSR are found to be in excellent agreement with the experimental data of Newcomb and co-workers. This match between experiment and theory makes a strong case that the reaction occurs via TSR mechanism.