Volume 24, Issue 7

The formation and composition of thorium arsenates obtained by the interaction of thorium nitrate and different alkali arsenates (meta, pyro and ortho) at specific pH levels 7.2, 8.3 and 11.1 have been studied by employing electrometric techniques involving amperometric, pH, potentiometric and conductometric titrations. The results provide cogent evidence for the formation of three thorium arsenates having the molecular formulae ThO 2 ·2 As 2 O 5 , ThO 2 ·As 2 O 5 and 3 ThO 2 ·2 As 2 O 5 in the vicinity of pH 4.2, 4.9 and 5.6 respectively. Analytical investigations of the compounds have also been carried out which substantiate the results of electrometric study.

The ammonolysis of a chlorophosphorane is characterised by the side by side substitution and condensation competing with one another. The different results fit into one reaction model from which the determining factors may be derived. Within the normal temperature range condensation proceeds only as long as both Cl and NH 2 functions at the phosphorus are present. Presubstitution by dialkylamines reduces condensation. Thus the partially alkylsubstituted tetraamino phosphonium and hexaamino diphosphorus nitride salts P (NR 2 ) 2 (NH 2 ) 2 ⊕ , N [P (NR 2 ) (NH 2 ) 2 ] 2 ⊕ and N [P (NR 2 ) 2 (NH 2 )] 2 ⊕ are synthesised.

ZnIn 2 S 4 geht bei 40 kbar, 400°C in eine Hochdruck-Modifikation mit normaler Spinellstruktur über.

Aus der Hochdruckmodifikation des AgInTe 2 mit NaCl-Struktur (AgInTe 2 -II) bildet sich bei Atmosphärendruck eine metastabile Phase mit Zinkblendestruktur (AgInTe 2 -III). Die röntgenographischen Untersuchungen sprechen gegen eine teilweise Besetzung von Oktaederplätzen durch Kationen. Wahrscheinlich handelt es sich um eine Phase der Zusammensetzung Ag 3x In 2,66-x Te 4 , die aus AgInTe 2 -II durch Ag 2 Te-Abspaltung entsteht.

CaMgSi, CaMgGe und CaMgSn sind isotyp und kristallisieren im geordneten Anti-Blei (II) - chloridgitter. Im Gegensatz zu allen bisher bekannten E-Phasen sind in den neu aufgefundenen nur Hauptgruppenelemente enthalten.

POFCl 2 konnte aus Monofluorphosphorsäure und Phosphorpentachlorid hergestellt werden. Umsetzungen von gemischten Phosphorylhalogeniden mit Mercaptanen und Trimethylhydrazin ergeben: Pyrophosphoryltetrafluorid reagiert mit wasserfreiem Hydrazin zur ersten Phosphor-Fluor-Hydrazin-Verbindung. IR-, 31 P-, 19 F- und 1 H-KMR-Spektren sowie Dichten, Brechungsindizes und Massenspektren werden angegeben.

Selenocarbohydrazid wurde erstmals als Komplexligand eingeführt. Die dargestellten Verbindungen Fe (SeCN 4 H 6 ) 2 (SCN) 2 , Cu (SeCN 4 H 6 ) 3 Cl 2 , Zn (SeCN 4 H 6 ) 2 Cl 2 und Cd (SeCN 4 H 6 ) 2 Cl 2 wurden IR-spektroskopisch und röntgenographisch untersucht. Es wird gezeigt, daß diese Komplexe ganz analog den entsprechenden Metallkomplexen des Thiocarbohydrazids aufgebaut sind. Danach tritt das Selenocarbohydrazid als zweizähliger Ligand auf, wobei das Selen-Atom als Donator-Atom fungiert.

The solid-state polymerization of functional derivatives of 2,4-hexadiin-1,6-diol caused by light or by heat was investigated. A qualitative survey demonstrates that the presence of groups capable of hydrogen-bonding are one of the most important factors for solid-state reactivity of conjugated triple-bonds. Compounds which do not form hydrogen-bonds were unreactive in most cases. Urethanes were the most reactive class of derivatives, 2,4-hexadiin-1,6-diol-bis-phenylurethane giving the best results. The relation and the reactivity of several modifications of this compound are described. Heating of one modification of 2,4-hexadiin-1,6-diol-bis-phenylurethane at temperatures between 70 and 120°C yielded in a topotactic reaction highly crystalline fibres of a coppercoloured polymer. Time-conversion studies were made and the activation energy of the polymerization determined to 19 kcal/mole. The mechanism of polymer-formation is discussed. It is highly probable that poly-1,4-bis-phenylcarbamoyloxymethyl-trans-butatrien, a polymer with three cumulated double-bonds per repeating-unit, is formed by a 1,4-addition reaction.

Chemical synthesis of C-4 tritium labeled 1′-(2′-deoxy-β-ᴅ-ribofuranosyl) -5-ethyluracil, also named as 5-ethyl-2′-deoxyuridine, a virostatic compound of therapeutic value, is described. The β-configuration has been derived from its optical rotatory dispersion spectrum, NMR spectrum and from its enzymatic hydrolysis. Incorporation of 5-ethyluracil into DNA of phages, bacteria and of mammalian cells has been already demonstrated. To follow the photochemical behavior of 5-ethyluracil in DNA, valid information in vitro can be expected from experiments with the 5-ethyl-2′-deoxyuridine alone; because we have already shown that contrary to 5-ethyl-, 5-propyl- and 5-butyluracil their N-1 and/or N-3 substituted mono and/or di-alkyl derivatives undergo photodimerisation. Similarly, as expected 5-ethyl-2′-deoxyuridine dimerises upon U.V.-Irradiation also (48%). Under the same experimental conditions thymidine dimerises practically to same extent as well (49%). From these results in vitro it follows that replacement of thymidine with 5-ethyluracil into DNA should not essentially alter its normal behavior towards U.V.-light.

The synthesis of tripeptides containing L-serine, glycine and L-proline is described. Five of the six possible tripeptides: L-seryl-glycyl-L-proline. L-seryl-L-prolyl-glycine, glycyl-L-seryl-L-proline, L-prolyl-seryl-glycine, glycyl-L-prolyl-L-serine, and L-prolyl-glycyl-L-serine were prepared by the azide method without masking the hydroxyl group of serine. The glycyl-L-prolyl-L-serine was only obtained from tert-butyloxycarbonyl-glycyl-L-prolyl-O-tertbutyl-L-serine-tert-butylester. The protecting groups can be removed by formic acid in 15 hours at 36°.

The polycondensation of the tripeptides L-seryl-glycyl-L-proline, L-seryl-L-prolyl-glycine, glycyl-L-serlyl-L-proline, L-prolyl-L-seryl-glycine, glycyl-L-prolyl-L-serine and L-prolyl-glycyl-L-serine using tetraethylpyrophosphite, bis-o-phenylene pyrophosphite and dicyclohexylcarbodiimide/N-hydroxysuccinimide according to WÜNSCH and DREES is described. The polymer products were fractionated on Sephadex ** G 25 and G 50 and their molecular weight determined by V e /V 0 .

The autoxidation of NaSH and Cysteine in the presence of heavy metal ions is accompanied by chemiluminescence due to the formation of O 2 ⊖ or adequate compounds as intermediates. The observation of the luminescence intensity and its time dependence has been used as analytical indication of the occurrence of electron transfer reactions from - SH to O 2 . This enabled the study of the influence of different catalytic promoters. The efficiency of different metal ions could easily be demonstrated by their enhancement of light production during the reaction of NaSH with molecular oxygen. Cu (II) as one of the most efficient catalysts was also applied in the form of different complexes. Because it would catalyse the oxidation of cysteine, glutathione and other electron donors of biological interest, the influence of the nature of the ligands of the complexes was investigated. In the case of cysteine only complexes with stability constants of medium strength and planar configuration acted as effective catalysts. Therefore it has to be assumed that for an effective electron transport to the loosely bound oxygen the cysteine molecule has to enter the inner sphere of the complex. The much longer time of luminescence of this reaction (4 -10 min) compared to the short time luminescence caused by free O 2 H. OH and H 2 O 2 indicates that these intermediates are stabilized by binding to the Cu (II) -complex as in compounds (I), (II) and (III) of oxidizing enzymes.

Zum Nachweis einer adaptiven Ureasebildung werden in den Acetonpulver-Extrakten aus Micrococcus denitrificans die spezifischen Aktivitäten der Urease und Arginase nach Kultur des Organismus unter aeroben und anaeroben Bedingungen mit jeweils verschiedenen N-Quellen (NH 4 Cl + KNO 3 ; Harnstoff, Ornithin, Citrullin, Arginin) bestimmt. Die Versuchsergebnisse zeigen, daß bei M. denitrificans nur Harnstoff sowohl unter aeroben als auch anaeroben Kulturbedingungen die Ureasebildung induziert (= Substratinduktion). Die Aminosäuren des Ornithin-Cyclus unterdrücken in anaerober Kultur die Ureasesynthese, obwohl Arginaseaktivität vorhanden ist. Hohe Ammonium-Konzentrationen hemmen die Ureasebildung unter beiden Kulturbedingungen vollständig ( = Endprodukthemmung). Diese Totalhemmung erfolgt in Gegenwart von Harnstoff, der durch eine Arginase freigesetzt wird, die in den auf NH 4 Cl + KNO 3 in anaerober Kultur gezogenen Zellen die höchste bei diesem Organismus gefundene spezifische Aktivität hat.

Female rats have been employed for a study of the reactivity of zinc ions on RNA and protein biosynthesis of liver nuclei. Intraperitoneal injections of 20 μmoles of this metal ion have been found to stimulate RNA biosynthesis up to 80% and a 40% increase of protein synthesis was observed under the same conditions. The precursor for RNA synthesis was [6- 14 C] -orotic acid and [l- 14 C]-ᴅʟ-leucine served as a label for nuclear protein. Low Zn 2 ®-concentrations showed no reactivity, even when zinc-deficient rats were used. DNA-dependent RNA-polymerase activity was progressively diminished when increasing amounts of Zn 2⊕ -ions were added in vitro to the incubation mixtures. However, RNA-polymerase activity was strongly stimulated following a 10 h pulse of Zn 2 ® prior to the isolation of liver nuclei.

The sequence of amino acids within the coat protein of the strain Holmes rib grass of tobacco mosaic virus (TMV) has been determined. In this communication the amino acid compositions of the coat protein and of all tryptic peptides are reported. Furthermore the experimental details are given for the elucidation of the amino acid sequences within the first three tryptic peptides, containing 61 amino acids. It has been found that the strain Holmes rib grass differs very extensively in the primary structure from the other TMV strains whose sequences are known. It differs from each of the other strains in more than 50% of the amino acid positions and it contains two amino acids less per protein subunit than the other TMV strains.

Experimental data for determining a) the amino acid sequences of eight tryptic peptides containing 95 amino acids and b) the order of the tryptic peptides are given. Combining the data of this and of a previous paper the complete amino acid sequence of the coat protein of the TMV strain Holmes rib grass (HRG) is established (Fig. 5). It is compared with three other TMV strains the sequences of which have been determined before (Fig. 6). Differences and similarities between the sequences of the four TMV strains are discussed. HRG has a deletion of two amino acids and it is the most distantly related of the four TMV strains. When the sequence of HRG is compared to that of any of the other strains it turns out that in each case more than 50% of the 156 positions contain different amino acids (Fig. 7). The number of positions with the same amino acid in all strains and mutants so far studied is 30 per cent. These positions are not randomly distributed but clustered mainly in two regions. This finding probably reflects the restriction of amino acid exchanges by the spatial structure of the viral rod.

DNA isolated from Coli bacteriophage T1 was irradiated in 0.165 ᴍ NaCl with γ-rays. The molecular weight was determined by measurement of the sedimentation coefficient and viscosity. An analysis of the boundary permits the determination of the sedimentation distribution. The distribution of sedimentation coefficients obtained at various DNA concentrations were extrapolated to zero concentration and were transformed into molecular weight distributions. These were used to calculate the weight average molecular weight M w and the number average molecular weight M n . The molecular weight of T1-DNA was found to be 32· 10 6 . After irradiation at a concentration of 200 μg/ml, double breaks as well as intermolecular crosslinks could be determined. The number of double breaks showed a rise with dose that can best be described as composed of a linear and a quadratic term. At low doses the crosslinks increase linearly, the rate being approximately half of that for the linear part of the double breaks. After higher doses, where most of the molecules are degraded, apparently no additional crosslinks are produced. No crosslinks were seen in DNA degraded by DNase. The influence of the DNA concentration on the degradation and the formation of crosslinks is discussed.

1. In der Embryogenese und Regeneration wird die Proliferation und Differenzierung der Epidermiszelle von der Dermis, wahrscheinlich mit besonderer Bedeutung des Kollagens gesteuert. Malignes Wachstum der Epidermiszelle wird als ein Primärdefekt der Dermis bzw. ihres Kollagens und den dadurch bedingten Ausfall der Steuerung aufgefaßt. Untersucht wird daher der Einfluß eines in Benzol gelösten Cancerogens auf das Kollagen der Dermis. 2. Unter dem Einfluß von Benzol steigt die Kollagensynthese und es findet sich wesentlich mehr und nach den Vernetzungsverhältnissen jüngeres Kollagen. 3. In Benzol gelöstes Cancerogen scheint die Kollagensynthese stark zu senken. Das Kollagen nimmt in allen Vernetzungsstufen gleichmäßig ab. 4. Verletzte Haut, die mit Cancerogen behandelt wurde, zeigt zusätzlich zu der gesenkten Kollagensynthese einen stärkeren Abbau der höher vernetzten Kollagenanteile. Größere Mengen Hydroxyprolin-hältiger molekularer Bruchstücke sprechen für eine kollagenolytische Aktivität. 5. Die gegen die Induktion von Carcinomen durch Carcinogene resistente Schwanzhaut (resistent nur in sito) zeigt außer der durch Benzol erhöhten Kollagensynthese keine der oben beschriebenen Veränderungen. 6. Es wird angenommen, daß das Carcinogen die Kollagensynthese stört. Dadurch wird die im Wundepithel auftretende Kollagenasesynthese im Ausheilungsprozeß durch Ausfall neu aufgebauter Kollagene nicht blockiert. Es wird im Gegenteil durch weiteren Abbau von Kollagen durch die Kollagenase der Epidermiszellen jeder steuernde Einfluß der Dermis auf die Epidermis aufgehoben. Die Epidermiszelle entgleitet ihrer zwischengeweblichen Kontrolle und wird unter bleibender Kollagenasesynthese maligne.

Im Granulationsgewebe wird die Synthese sowie die Vernetzung des Kollagens durch Benzol gebremst. Methylcholanthren hebt diese Wirkung teilweise wieder auf. Der in früheren Arbeiten nachgewiesene kollagenolytische Effekt von Methylcholanthren auf die Dermis findet sich beim Granulationsgewebe nicht.

1. The stability of NNMG with respect to pH was investigated. A maximum, with a half-life of 40 hours, was found in phosphate-citric acid buffer at pH 5. The stability decreases quickly with increasing concentration of hydroxyl ions. At the optimal mutation rate (pH 6, 37°, and shaking) the half-live is only 14,4 hours. 2. NNMG uptake (using labelled NNMG) and mutation rate in the range pH 3,5 — 8,0 show an optimum at pH 6,0/6,5 for both Escherichia coli B and the red ad - mutant E 188 of Saccharomyces cerevisiae. The pH-dependence of NNMG uptake and mutation rate is similar. 3. The methylation of nucleic acids by means of [ 3 H]-methyl-NNMG or [ 14 C] -methyl-NNMG in phosphate-citric acid at 37° while shaking increases with the growing concentration of hydroxyl ions. At the optimal mutation rate, however, NNMG methylates relatively poor. 4. Incorporation of radioactive NNMG into Escherichia coli B results in labelling of nucleic acids and proteins. The labelling of DNA shows an optimum at pH 6. The extent of methylation was found to be higher in vivo than in vitro. 5. In the presence of cysteine or β-mercaptoethanol nucleic acids are methylated more intensively than in the cysteine-free control experiment. After one hour the methylation was about twentyfold higher in the presence of cysteine or β-mercaptoethanol compared to the cysteine-free control experiment. The methylation in presence of SH-compounds shows a maximum at pH 6. The explanation of both a higher methylation rate and its optimum at pH 6 suggests the activation of methylation by means of sulphhydryl-groups.

Differential derepression of the genome of potato tuber cells can be initiated by slicing the tissue into disks. The consequence of this procedure on the cells of the wound surface is dedifferentiation and cell division followed by redifferentiation to a suberized phellem cell. The drift of glucose-, glucose-1-phosphate-, glucose-6-phosphate-, fructose-6-phosphate- and 6-phospho-gluconatelevels has been determined in the derepressed tissue. With the exception of 6-phospho-gluconate all intermediates so far investigated showed a rise in concentration after derepression. This is interpreted as a consequence of altered enzymic activities which were estimated for phosphoglucomutase, hexokinase, phosphoglucoisomerase, gluco-6-phosphate- and 6-phosphogluconatedehydrogenase. The two dehydrogenases were activated after derepression, the activation represented a de-novo-synthesis, as was demonstrated with the inhibitors Actidione (translation) and p-Fluorophenyl-alanine (protein synthesis in general). Hexokinase and phosphoglucoisomerase were not severely affected by cutting the tissue. Phosphoglucomutase was degrated rapidly, the degradation being dependent on protein synthesis. The importance of an enhanced activity of the pentose phosphate shunt for the stressed cell is emphasized and the possibility of an alteration in the osmotic pressure within the cell and especially in the nucleus — a primary consequence of wounding — as a cause of derepression in potato tuber cells is discussed.

Die Cellulose pflanzlicher Schleime (von Quittenkernen und Senfsamen) wurde direkt, nach Aceton-Fällung und nach Alkali-Extraktion im Negativkontrastverfahren (Phosphorwolframsäure und Uranylacetat) auf hydrophilisierten Trägerfolien elektronenmikroskopisch untersucht. Die einzeln liegenden Fibrillen besitzen Breiten von 100 Å bis hinunter zu 10 —12 A. Derartig dünne Fibrillen stellen die kleinsten bisher im Elektronenmikroskop nachgewiesenen Polysaccharidstrukturen dar. Darüber hinaus läßt sich feststellen, daß die für Cellulosefibrillen charakteristische bandförmige Struktur auch für Fibrillen mit Abmaßen im Bereich der „Elementarfibrillen“ von FREY-WYSSLING und MÜHLETHALER zutrifft. Die kleinsten noch gut meßbaren Fibrillenbänder haben Querschnitte von etwa 12 —15·30 —40 Å. Die Messungen widerlegen bisher weithin akzeptierte Vorstellungen von einer Elementarfibrille mit einem Querschnitt von ca. 35·35 Å als kleinster Struktureinheit nativer Cellulose. Aus den gefundenen Fibrillendimensionen ergeben sich Folgerungen für die gegenwärtig zur Diskussion stehenden Cellulose-Modelle.

Aus der Phosphatidfraktion der Erdnuß (Arachis hypogaea L.) wurde ein phosphorhaltiges Sphingoglykolipid isoliert, das in der qualitativen und quantitativen Zusammensetzung seiner Sphingosinbasen, Fettsäuren und Zuckerbausteine mit dem Phytoglykolipid (PhGL) aus Soja und Mais große Ähnlichkeit aufweist. Nach dem Ergebnis der Mol.-Gew.-Bestimmungen ist für das Erdnuß-PhGL eine Polymerstruktur wahrscheinlich.

Der Pigmentgehalt von fünf Stämmen der Grünalgengattung Protosiphon wurde analysiert. Bei ausreichender Stickstoffversorgung entspricht die Zusammensetzung der Chlorophylle und Carotinoide der höherer grüner Pflanzen. Bei Stickstoffmangel werden dagegen diese Pigmente in wesentlich geringeren Konzentrationen synthetisiert und zusätzlich neue Carotinoide, sogenannte Sekundär-Carotinoide gebildet. Neben den bereits bekannten Sekundär-Carotinoiden 4-Oxo-, 4.4'-Dioxo-, 3-Oxi-4.4'-dioxo-, 3-Oxi-3.4.4'-trioxo- und 3.3'-Dioxi-4.4'-dioxo-β-carotin konnten noch 4-Oxi-4'-oxo- und 4-Oxi-3'.4'-dioxo-β-carotin neu isoliert werden (Tab. 1). Die Oxi-Verbindungen sind mit Capryl-, Caprin-, Laurin-, Myristin-, Palmitin- und Stearinsäure in unterschiedlichen Kombinationen verestert.