Band 23, Heft 6

A large number of aminophosphines were prepared to study the kinetic processes. It could be shown that at room temperature there is rapid nitrogen-inversion but slow phosphorous-inversion. At higher temperatures ( + 80 °C), a rapid chlorine-exchange takes place with inversion of configuration at phosphorous. At low temperatures ( — 80 °C), rotation around the N-P-bond was slow. A dependence of the barrier of rotation on the size of the substituents could be recognized. It is possible that p π -d π -bonding is partially responsible for the relatively high barrier of rotation compared with derivatives of ethane and hydrazine.

Vom GaOOH, GaOOD und den entsprechenden partiell deuterierten Präparaten wurden die IR-Absorptionsspektren im Bereich von 10 000 bis 33 cm -1 aufgenommen und Banden den OH-Valenz- und OH-Librationsschwingungen und Schwingungen der GaO 6 -Oktaeder zugeordnet. Die Multiplizität der OH-Banden ist im wesentlichen auf eine Wechselwirkung der Schwingungen der OH-Gruppen in der Einheitszelle zurückzuführen. Banden bei 1069 cm —1 und 1031 cm —1 im IR-Spektrum von GaOOD werden auf die beiden Librationsschwingungen einer isolierten OH-Gruppe zurückgeführt.

Chlorine containing phosphonic acid esters (tridilorphon-type) have been investigated quantitatively by ESR after X-irradiation at room temperature. Radical yields are between 0.2 and 1.7 radicals per 100 eV. In the case of trichlorphon the radical concentration is 7.5·10 18 spins per gram at 40 Mrad. Stabilisation and kinetics of radiation-induced radicals in the solid state matrix at high irradiation doses in dependence of storage time, oxygen-effect and temperature are discussed. The obtained results suggest a model for the behaviour of the matrix at high irradiation doses. According to this model the lattice of molecular crystals is modified by the accumulation of recombination products arising from the induced radicals. These lattice imperfections cause a diminution of stabilizing properties for the radicals. The decrease of the dose-yield-curve at higher doses than 40 Mrad and the dose-dependent radical kinetics during storage can be explained by this model.

Free tartaric acids, various tartrates, malic, hydroxymaleic, fumaric and aspartic acid, as well as propane diol-1.2 have been labelled by the Wilzbach method. In propane diol, hydrogen attached at C-2 is substituted by tritium three times faster than a hydrogen atom of the methyl group whereas that at C-l is substituted two times faster. Splitting of a carbon-carbon bond and fixation of tritium is eight to nine times more probable than the substitution of hydrogen by tritium. The OH group in propane diol as well as in tartaric and malic acid is more often replaced by atomic tritium than hydrogen atoms fixed at carbon. During the formation of malic acid from tartaric acid the second center of asymmetry is not attacked. The replacement of the OH group occurs in the cases of the free acid and the dimethylester to a high degree under inversion. Is the calcium or copper salt exposed retention prevails. In meso tartaric acid the carbon bound hydrogen is substituted with 12% inversion. When glycolic acid is formed from copper L-tartrate 29% inversion takes place.

The alkaloid echinorine (I) is the only alkaloid occurring in the fruits of Echinops ritro L. and Echinops sphaerocephalus L. The previously reported echinopsine (III) was found to have been formed from echinorine (I) during the isolation procedures or during storage of the plant material. In addition to echinopsine (III) a further alkaloid echinopsidine (II) is found under certain conditions. Our experiments show that this compound is formed if extracts of the fruits are treated with ammonia. When 15 N labelled ammonia is used, the isotope is found in the echinopsidine formed. By degradation of the labelled compound to echinopsine and ammonia it is shown that the isotope 15 N is located in the imino group only. This result shows conclusively that echinopsidine can be formed by ammonolysis of echinopsine. A small amount of echinopsidine is also found in the extract of fruits on addition of sodium carbonate. No free ammonia could be detected in the extract adjusted to pH 8.4 following extractions of the fruits with methanol or a mixture of methanol and acetic acid. The addition of sodium carbonate, however, liberated small quantities of ammonia, possibly from arginine or other N containing substances and this could explain the formation of small amounts of echinopsidine without the addition of ammonia to the extracts under these conditions. Other products are obtained from echinorine in the presence of amino acids (e.g. glycine, alanine or phenylalanine) and sodium carbonate. Here the complete degradation of the alkaloid and the formation of new compounds (and echinopsine) was observed.

According to the proposed mechanism, the enzymic formation of dextran from sucrose consists of two reaction steps: the propagation reaction forming polymer molecules by an insertion type growth, and the acceptor reaction leading to the termination of the polymer chains. This mechanism is of a more general applicability; it explains hydrolysis, transfer and poly reactions. A complete kinetic analysis is given for the dextran formation and values for the reaction constants V m , K m and K a (the Michaelis constant of the acceptor reaction) have been evaluated. Very good agreement between the rate data calculated from the mechanism and the experimental data has been obtained. From experiments with a series of radioactively labelled acceptors it was established that the acceptor reaction, in fact, proceeds as proposed by the mechanism. Further, it was found that strong acceptors, leading to the formation of low molecular weight dextrans, do not inhibit the reaction rate, and that weak acceptors, which inhibit the reaction rate, have only a small effect on the molecular weights. This correlation has also been demonstrated in terms of the proposed reaction mechanism.

The concentration of free radicals in freshly prepared ratliver-mitochondria was investigated under different conditions with the aid of electron spin resonance spectroscopy. The electron spin resonance signal at g=2.004 was measured at 77 °K and related to the weight in milligrams of mitochondrial protein. The concentration of free radicals increases with rising body weight or, in other words, with decreasing growth rate of the animals. A plateau is reached with about 10 13 radicalcenters per mg protein for grown animals. The concentration of free radicals is 150% of the control value after fasting for 24 hours, whereas it is below the detectable level in cells of ascites hepatoma. We conclude that the concentration of free radicals determined at g = 2.004 is a function of mitochondrial activity. After whole body x-irradiation with a dose of 900 R, a significant decrease of 20% of the signal amplitude was measured. Increasing the dose to 1800 R did not decrease the radical concentration further. These results might be connected with the diminished activity of some flavin enzymes observed in liver mitochondria after x-irradiation in vivo. In further experiments we have incubated the mitochondria in vitro with various inhibitors of flavin enzymes. The individual inhibitors (ammonium-ions, KCN, acetonitrile, glucose) and also malonate reduce the concentration of free radicals to 80% of the control value in the mean if the particles are incubated at 37 °C for 5 minutes. The effect of malonate adds to the effects of the other inhibitors. The inhibitory effect of 2,4-dinitrophenol develops only after a longer incubation time. These results are discussed in connection with the influence of the same inhibitors on the Pasteureffect of yeast cells. Some specific inhibitors of the respiratory chain (Amytal, antimycin A, oligomycin) also diminish the concentration of free radicals.

The isomerisation of the a and b forms of several acid cyano-aquo-corrinoids (with one to four carboxyl groups or one phosphoric acid group) in aqueous medium was investigated. The reaction is accelerated by light, heat, anions (e.g. acetate ion) and carbon monoxide. For all cyano-aquo-corrinoids with carboxyl groups investigated the equilibrium a ⇄ b shifts in the direction a → b when the carboxyls dissociate; in the case of carbonic acids prepared from cobyric acid, the shift grows with the number of the carboxyls. On the contrary, the cyano-aquo-corrinoids with a phosphoric acid group (cobinamide phosphate and its three isomers) exist as a mixture of about 55 per cent a form and about 45 per cent b form in the entire pH range (2.5 to 9) investigated. It is shown that the isomerisation of the cyano-aquo-corrinoids follows the known rules of ligand exchange (and of the connected reactions, such as steric change, racemisation, and disproportionation) for cobalt (III) complexes.

DNA polymerase from Escherichia coli was studied using a new technique of micro-disc-electro· phoresis on polyacrylamid gel carried out in 5 μl capillary tubes. Two methods for the identification of DNA polymerase among other protein zones of crude preparations were developed: 1. The binding test in which DNA polymerase forms a complex with poly d (A — T) in the presence of Mg 2⊕ ions, d ATP, and dTTP. This complex of rather high molecular weight cannot enter the separation gel and remains in the interphase between concentration and separation gel. Consequently, the appropriate zones are missing after staining with amido black 10 B in acetic acid. 2. The polymerisation test in which the separation gel contains a minute amount of poly d (A—T) primer, sufficient to induce an extensive synthesis of poly d (A—T) by DNA polymerase in the gel when incubated with d ATP and dTTP in the presence of Mg 2⊕ ions. The newly synthesized poly d (A— T) is stained with pyronine and can be estimated with a sensitive microdensitometer. The application of this micro-method to biochemical problems is discussed. Earlier findings of a multiplicity of E. coli DNA polymerase are confirmed.

In zwei getrennt durchgeführten Versuchen mit Rattenmännchen und kastrierten Rattenmännchen wurde der Einfluß von P-armer und Ca-reicher Diät, von Östrogen und von Progesteron auf den 90 Sr-Stoffwechsel untersucht. P-arme und Ca-reiche Diät erniedrigt den 90 Sr-Gehalt. Östrogenverabreichung führt zu einer erhöhten 90 Sr-Retention. Beim Progesteron konnte kein Einfluß auf die 90 Sr-Ausscheidung nachgewiesen werden. Bei kombinierter Verabreichung addieren sich die Wirkungen der 3 Behandlungsarten.

The transcription of the homopolymer templates poly dA: dT and poly dG: dC with RNA polymerase is described. In both cases the pyrimidine strands are transcribed preferably, as shown by studies in which only one or both of the triphosphates complementary to the strands were present as substrates. A poly dA: dT dependent poly A synthesis which had reached a plateau could no longer be stimulated by addition of new poly dA: dT. If instead poly dG: dC and GTP were added, the beginning of a poly G synthesis could be observed.

The effect of 0,0-Diethyl-O-p-nitrophosphate (Paraoxon) on the growth of Tetrahymena in culture was investigated. At all concentrations tested (dilutions 1: 10.000 to 1 million) growth was depressed. After pretreatment with Paraoxon at a dilution of 1:100.000, resistence to the compound developed. Thus 5 days pretreatment increased the survival time in high concentrations of Paraoxon threefold, and 14 days ninefold, when compared with controls. Resistant and non-resistant cells were compared. After 8 days pretreatment oxygen consumption and catalase activity doubled. Acid phosphatase activity doubled following 4 weeks pretreatment and a twofold increase in cholinesterase activity was seen after 8 weeks pretreatment. No specific esterases capable of splitting phosphate esters could be shown in resistant cells. It may be significant that in resistant cells enzymes sensitive to Paraoxon are increased.

The metabolism of dimethoate and its N-butyl homologues in tomato plants has been studied by use of 32 P and 35 S labelled initial products. The preparation of thiol- 35 S-labelled dimethoate is described. Formation and break down of dimethoxon and N-tert.-butyl-dimethoxon have been measured by radio-thin layer chromatography. The calculated biological half times have been compared with those in aqueous buffer solutions; remarkable differences between dimethoate and dimethoxon derivatives have been observed. The extension of the N-alkyl chain causes a more rapid biological breakdown. The technique described is also useful for the comparison of other organophosphorus compounds (OPC).

Two hexokinase activities of different substrate specificity (fraction I and II) have been isolated by means of column chromatography on DEAE-cellulose from the antennal gland of the crayfish Orconectes limosus (RAFINESQUE). Chromatographically, the two fractions are uniform. Out of 10 sugars, fraction I converts mannose and fructose only; the phosphorylation of fructose amounts to 20% only of the conversion of mannose. Fraction II phosphorylates six out of the 10 sugars tested, and in its substrate specificity it corresponds to an unspecific hexokinase. The products of phosphorylation are with both enzymes for all substrates sugar-6-phosphates. The Km values of fraction I for mannose and fructose are 3,9·10 -5 and 2,9·10 -3 Μ, those of fraction II for glucose, mannose and fructose 7,1·10 -5 Μ, 8,0·10 -5 Μ and 6,7·10 -3 Μ. The same enzymes have been found in the heart and in the hindgut, with proportions in the three organs, however, different. Experiments with the crude extract had the following results as regards the properties of the enzymes: the activity is not particle-bound. Optimal activity is obtained at a pH-value of more than 7.7. High concentrations of salt as well as pH-values below 6 or above 8 rapidly destroy the activity in storage.

The diplopods Cingalobolus bugnioni and Aulacobolus excellens possess an epicuticle formed of lipoproteins. But unlike in insect cuticles, the epicuticle lacks an outer lipid layer. The epicuticle is found only in the animals collected in summer months. At the commencement of the rainy season the new cuticle that is formed following moulting is without an epicuticle. The periodical presence of the epicuticle is of ecological significance. A study of the transpiration rates using animals with and without an epicuticle showed that in the former evaporation of water through the cuticle was much less than in the latter. It is suggested that the presence of an epicuticle during summer season is of adaptive value in that the restricted permeability properties of the epicuticle enable the animals to conserve their water resources. In the rainy season when there is plentiful supply of water in the environment the animals are without an epicuticle as there is no necessity to restrict water loss. The periodical absence of the epicuticle has been discussed in the light of previous reports on the cuticular organization of millipedes.

Histological investigation of the gonads of 24 specimens of parrotfishes, belonging to several species, revealed the existence of secondary males and of females changing into males in this family. These findings are very similar to those having been described in protogynous wrasses. Considering various data in the literature on sexual dichromatism and spawning behavior, it may be concluded that parrotfishes are protogynous, just as some wrasses, to which they are closely related.

Ramalina subdecipiens STEIN. von den Kanarischen Inseln enthält als sekundäre Inhaltsstoffe neben (+) -Usninsäure und Salazinsäure das neue Depsid 4-O-Desmethylbarbatinsäure, dessen Struktur aus massen- und NMR-spektroskopischen Untersuchungen sowie der Hydrolyse zu β-Orcin-carbonsäure folgt.

Tetrahydrobiopterin which is present in larval skin of Triturus completely disappears after metamorphosis. In T. cristatus it is mainly riboflavin which remains in the dorsal skin, while in T. alpestris it is mainly isoxanthopterin as well as smaller amounts of pterincarbonic-acid (6), 2-amino-4-hydroxypteridin and (in T. alpestris) biopterin which are found. In T. vulgaris all 4 compounds are found in about equal amounts. The regeneration buds of the tail in T. cristatus and T. alpestris are dark and show melanophores in the epidermis. Moreover, the tetrahydrobiopterin has reappeared whereas riboflavin and isoxanthopterin are diminished respectively. As differentation progresses, the ratios tetrahydrobiopterin/riboflavin and tetrahydrobiopterin/isoxanthopterin gradually regain their “adult” values. The slightly greyish regeneration bud in T. vulgaris, however, does not show any melanophores in the epidermis, nor does tetrahydropterin of the larval stage reappear. The relations between repigmentation of the regeneration bud and the biosynthesis of tetrahydrobiopterin from its purin-precursor are discussed.

Crown-gall-Gewebe von Datura innoxia wurde mit subletalen Röntgendosen (2 und 3 kR, DL 206 R/min, 20 mA, 200 kV, Focusabstand 50 cm) bestrahlt und der Einfluß der Bestrahlung auf den 32 P-Einbau (4 Stdn. Inkubationszeit) in folgende, mittels MAK-Chromatographie aufgetrennte Nucleinsäurefraktionen untersucht: sRNA, DNA, rRNA und mRNA. Neben teilweisem Abbau der hochmolekularen RNA wird der 32 P-Gehalt der Nucleinsäuren erniedrigt. Nach Einwirkung von 2 kR ist vorwiegend mRNA betroffen, während 3 kR den 32 P-Einbau in alle Fraktionen hemmen. Die Ergebnisse werden im Zusammenhang mit der einschlägigen Literatur diskutiert.