Chemical Synthesis,Proton NMR. Parameters,Hydrogen- and Calcium-Ion. Complexation of L-γ-Carboxyglutamyl-L-γ-carboxyglutamic Acid and D-γ-Carboxyglutamyl-L-leucine

The purpose of this communication is to describe the preparation and some properties of the first two synthetic peptides containing D - and L -γ-carboxyglutamic acid. Use was made of N-protected γ,γ′-di-t-butyl-γ-carboxyglutamic acids (D , L , and DL ) described earlier [1 a]. Preliminary ¹H-NMR. data (360 MHz) indicate a restricted rotation of the Gla side chain in the free amino acid as well as in the C-terminal Gla of Gla-Gla in H₂O solution at acid pH. The proton dissociation from Gla and Gla-Gla was studied by potentiometric titration and NMR. methods. The pH titration in the presence of Ca²⁺ ions shows that Gla-Gla has a much higher association constant for this cation than Gla. It is almost as great as that of prothrombin (pCa²⁺ = 3.2 vs. 3.5).     

Gold nanoparticle-enhanced surface plasmon resonance measurement with a highly sensitive quantification for human tissue inhibitor of metalloproteinases-2

Two different methods for the quantification of human tissue inhibitor of metalloproteinases-2 (TIMP-2) were developed using surface plasmon resonance (SPR) and gold nanoparticles for signal enhancement. The first method, a competitive assay, used TIMP-2 immobilized to the sensor surface and the inactive form of matrix metalloproteinase-2 (proMMP-2) (EC 3.4.24.24) adsorbed to gold nanoparticles. The sensor signals resulting from the interaction of MMP-2-gold nanoparticles with immobilized TIMP-2 were inversely proportional to the amounts of TIMP-2 of the sample. The measuring range for TIMP-2 was about 15–180 pM. The second method, a one-step sandwich assay, used proMMP-2 immobilized to the sensor surface and an anti-TIMP-2 monoclonal antibody coupled to gold nanoparticles. The lower detection limit of this assay format was 0.5 pM of TIMP-2. The binding signals were highly reproducible up to 100 pM of the inhibitor. The improvements obtained in TIMP-2 quantification over already existing tests could contribute to a better understanding and diagnosis of diseases like cancer.     

A photometric detector driven by beta radiation

It was recently found that typical Chromatographic carrier gases such as argon or nitrogen could be used in a modified flame photometric detector for general or selective determination of eluted molecules. The detector was powered not by a flame but by a radioactively stimulated, mild discharge. The luminescence arose from the second positive system of nitrogen (in argon), and various emissions from aroyl-containing molecules (in nitrogen).This study describes experiments that take away not only the flame but also the discharge: The energy that produces the luminescence is derived solely from the beta decay of⁶³Ni. Because of this low power input, the sensitivity of the present beta-driven photometric detector (-PD) is limited to about 25 ppm of nitrogen (in argon), and to about 5 pg/s for benzaldehyde and other well-responding aroyl compounds (in nitrogen). In accordance with mechanisms postulated earlier, other types of molecules do not produce significant responses in the absence of an electrical field.Material taken from doctoral thesis     

On the magnetic properties and the phase composition of the Cr2O3?MnOx-system (2 ≥ x ≥ 1.5)

The mixed oxide system Cr₂O₃? MnO_x (2 ≥ x ≥ 1.5) was investigated by X-ray diffraction, by measurements of magnetic susceptibility, and by chemical determination of excess oxygen (BUNSEN'S method). The Presence of the antiferromagnetic oxides Cr₂O₃, β-MnO₂, α-Mn₂O₃ and a ferromagnetic phase Cr_1?yMn_yO₂ was stated. The formation of the latter with fourvalent chromium is explained by a lattice induction effect of the MnO₂ (rutile type).     

Syntheses of bile pigments. Part 15. First unequivocal assignment of the absolute configuration of an urobilinoid bile pigment by X-ray diffraction analysis of its synthetic precursor

(?)-(4S,16S)-8, 12-bis[de(2-carboxyethyl)]mesourobilin-IIIα hydrochloride ( 8 ) has been synthesized from the enantiomerically pure 1,4,5,10-tetrahydro-1-oxodipyrrin-9-carboxylic-acid precursor 6a whose absolute configuration was determined by X-ray diffraction analysis of the N-[(S)-1-(1-naphthyl)ethyl] carboxamide 7b . The present results prove unequivocally that an (S,S)-configurated urobilin chromophore displays a negative Cotton effect in the VIS absorption range. However, the helicity of the inherently dissymmetric chromophore remains undetermined.     

Beitrag zur Kenntnis des Systems Vanadin—Chrom—Stickstoff

The System V–Cr–N has been investigated at 1100 and 1400 °C and at nitrogen pressures between 1 and 1000 atmospheres by X-ray techniques. VN and CrN on the one hand and V₂N and Cr₂N on the other are forming complete series of solid solutions. The phase field of the mononitride solid solution is dependent on nitrogen pressure and temperature conditions.

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Auszug aus der Diplomarbeit des Herrn Dipl.-Ing. Dr.W. Schebesta.     

PHYTOCHROME-MEDIATED GERMINATION: EFFECTS OF BRIEF HIGH TEMPERATURE TREATMENTS

Abstract— Brief high temperature treatments, applied early in the pregerminative period to radiation-requiring seeds of lettuce, inhibited both dark and radiation-induced germination. The inhibition increased with increasing incubation temperature. There was little difference in the germination percentage whether the inductive irradiation was applied before or after the high temperature treatment. When the high temperature treatment preceded induction, there was an increase in the radiation dosage required for maximum germination. These findings are interpreted in terms of lability of physiologically active phytochrome to higher temperatures.     

Darstellung und Reaktionen des 3-Ethinyl-2,4-diformyl-pentandials

Preparation and physical and chemical properties of 3-ethinyl-2,4-diformyl-pentandial (3 a) and its salts are described.3 a contains 2 malonaldehyde groups. Starting from3 a, 4H-pyranes, 4H-dihydropyridines, dipyrazoles, diisoxazoles, bisdiazepines and vinamidine derivates are obtained.

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Mit 1 Abbildung     

Unexpected differences in the alpha-halogenation and related reactivity of sulfones with perhaloalkanes in KOH-t-BuOH

Most alkyl phenyl sulfones are readily alpha-chlorinated with CCl(4) and alpha-brominated with CBrCl3 in KOH-t-BuOH via radical-anion radical pair (RARP) reactions. While isopropyl mesityl sulfone (4) is easily alpha-chlorinated with CCl(4), it was completely recovered when treated with the more reactive CBrCl3. Subsequent investigations showed the latter result to be due to the poor acidity of 4 together with the rapid depletion of CBrCl3 and KOH by their reaction with each other, and led to a variety of other important results. 4-Hydroxyphenyl isopropyl sulfone (6) is unreactive with either CCl4 or CBrCl3 in KOH-t-BuOH, its phenoxide anion strongly reducing the electronegativity of the sulfonyl group, thereby inhibiting alpha-anion formation. This effect is reversed by the electron-withdrawing influence of two alpha-phenyls, so that benzhydryl 4-hydroxyphenyl sulfone (8) is readily alpha-halogenated in KOH-t-BuOH with CCl4 or CBrCl3. On further contact with KOH-t-BuOH the alpha-halogenated sulfones from 8 are decomposed into benzophenone and phenol. While the alpha-halogenated derivatives of 4-methoxyphenyl benzhydryl sulfone (9) are stable to base, they are decomposed even under mildly acidic conditions into 4-methoxyphenyl 4-methoxybenzenethiolsulfonate (9c), phenol, and benzophenone. Mono-alpha-halogenation of benzyl phenyl sulfone (10) enhances the rate of the subsequent halogenation, so that alpha,alpha-dihalogenation is attained while much substrate is still present and the mono-alpha-halogenated product is not detected. The ease of reductive debromination of alpha-bromo sulfones with Cl3C- was correlated with the stability of the formed alpha-anions, explaining the success with alpha-bromobenzylic sulfones but failure with alpha-bromoalkyl sulfones. In the presence of air and the absence of competing halogenation, formation of the alpha-anions of alkyl aryl sulfones is quickly accompanied by oxidative cleavage by atmospheric O2, leading to the formation of arenesulfonyl alcohols, arenesulfonyl halides, and haloarenes.