Volume 22, Issue 8

Der Verlauf der Photooxydation bei Tieftemperatur wird in quantitativer Sicht am Di- und Triphenylamin aufgezeigt. Diese beiden offenen Arylamine spalten bei der photolytischen Primärreaktion ein Elektron unter Bildung eines Radikalkations ab. Die Kationen absorbieren mit ihrer längstwelligen Bande bei 650 nm und verursachen Blaufärbung der eingefrorenen Lösung; ein höherer Anregungszustand liegt bei 360 nm im Ultraviolett. Die Tieftemperaturphotolyse der geschlossenen Diarylamine N—CH 3 -, N—C 2 H 5 -, N—C 3 H 7 - und N-Phenylacridan ist bezüglich des Primärprozesses den offenen Arylaminen analog. Es werden zunächst blaugefärbte N-Radikalkationen mit Absorptionsbanden bei 650 und 360 nm gebildet. Bei ansteigender Konzentration und zunehmender Belichtungsdauer wird die Bildung eines neuen, orangen Radikals mit einer längstwelligen Absorptionsbande bei 520 nm nachgewiesen. Dabei sinkt die Konzentration des blauen Radikalkations laufend ab. — Durch Einfluß von OH ⊖ -Ion wird gezeigt, daß es sich dabei um ein durch H ⊕ -Abspaltung aus dem Radikalkation entstandenes C-Radikal handeln muß. Beim Tauen der Lösung auf —140 bis —150 °C rekombiniert ab —170 °C zuerst das Radikalkation reversibel zum Ausgangsacridan zurück, während das orange C-Radikal, beginnend ab —155 °C, in drei stabile Molekeln umgewandelt wird. Einerseits entstehen durch Disproportionierung aus diesem C-Radikal N-Alkylacridiniumkation und N-Akylacridananion, und andererseits bildet sich besonders bei O 2 -Anwesenheit ein N-Alkylacridon. Die Acridonbildung stellt einen Konkurrenzprozeß zur Disproportionierung des C-Radikals dar. Es wird daraus gefolgert, daß das C-Radikal Semichinoncharakter hat.

Die generelle Struktur der Spektren deuterierter Phosphorverbindungen ist theoretisch abgeleitet und diskutiert. Die Spektren einer Reihe deuterierter Verbindungen mit Phosphor der Koordinatenzahl 4 sind durch ihre Daten charakterisiert und teilweise abgebildet.

Die Untersuchungen wurden nach der mikrokatalytischen Technik (Pulstechnik) im Temperaturbereich zwischen rund 100 und 400 °C durchgeführt. Die Reihenfolge der Aktivität der Katalysatoren ist in etwa die folgende: MgSO 4 > BaSO 4 > BeSO 4 > Al 2 (SO 4 ) 3 > Li 2 SO 4 > K 2 SO 4 > Li 2 SO 4 /Al 2 (SO 4 ) 3 5 : 95 Mol-% > Cs 2 SO 4 . Die Katalysatoren mit den zweiwertigen Kationen gehören zu den aktivsten. Für die Reaktanten wurde in der Regel die folgende Reihe der Reaktivitäten gefunden: 2-Brombutan > 2-Chlorbutan > 1-Brombutan > 1-Chlorbutan > 2-Butanol > 2-Aminobutan > tert.-Butylbenzol. Die Aktivierungsenergie am aktiveren Katalysator ist mitunter die höhere. Besonders an MgSO 4 , dem aktivsten aller Katalysatoren, ist dieser Effekt, den man als Superaktivität oder Überkompensation bezeichnen kann, stark ausgeprägt.

Mit den in der vorhergehenden Mitteilung untersuchten Reaktionssystemen wurde unter denselben Bedingungen wie dort die Produktverteilung, d. h. das Verhältnis der drei linearen Butene, bestimmt. Mit zunehmender Temperatur nähert sich diese Verteilung zunehmend an das Gleichgewicht an. Mit abnehmender Temperatur nehmen die Abweichungen von der Gleichgewichtsverteilung zu, und zwar wird häufig cis-2-Buten vor trans-2-Buten bevorzugt. Diese cis-Selektivität scheint mit abnehmender Aktivität des Katalysators größer zu werden. Die Produktverteilung mit 1-Chlor- und 1-Brombutan ist der mit 2-Chlor- und 2-Brombutan erhaltenen sehr ähnlich. Lediglich Li 2 SO 4 macht eine Ausnahme. Im unteren Bereich des Temperaturintervalls erhält man ausschließlich 1-Buten. Ein Vergleich der Produktverteilung aus Eliminierungs- und Isomerisierungs-Versuchen läßt den Schluß zu, daß die Produktverteilung der Eliminierung, zumindest zu einem ganz erheblichen Teil, die Primärverteilung sein muß und nicht auf einer nachträglichen Isomerisierung beruht.

Durch Umsatz von aromatischen Verbindungen mit Hydroxyguanidin-O-sulfonsäure und ihren Alkyl-Derivaten lassen sich in Gegenwart von Aluminiumchlorid arylierte und gemischt aryliertalkylierte Guanidine darstellen. Das Isomerenverhältnis bei der Guanidierung von Toluol sowie die Konkurrenz-Reaktion zwischen Benzol und Toluol deuten auf einen elektrophilen Mechanismus hin.

Um Aussagen über die Herkunft des N-Atoms in der Pipecolinsäure machen zu können, wurde an Pflanzen von Phaseolus vulgaris Lysin-[2- 14 C,α- 15 N] und Lysin-[2- 14 C,ε- 15 N] verfüttert. Aus den Inkorporations-Versuchen geht hervor, daß die α-Aminogruppe des Lysins wesentlich besser in die Pipecolinsäure eingebaut wird als die ε-Aminogruppe.

8a- 14 C-Biopterin intraperitoneally injected into rats is secreted within a short time and in a nearly quantitative amount into the urine. After feeding, 90% of the substance remains in the organism. 7-biopterin is absorbed only in small amounts and is excreted to a large extent with the feces. The absorbed labeled biopterin is equally distributed throughout the body. After three days a measureable amount of activity is found in the serum as well as in the liver and adrenals. The same level of activity occurs in regenerating liver and ascites tumour cells. After chromatographic separation of a 5% TCA soluble extract obtained from 250 g of rat livers, only 10% of the total radioactivity was found in biopterin. The remaining activity appears mainly in a weakly basic, extremely labile component. Other pterines could not be demonstrated. No biopterin is found in the TCA insoluble liver fraction. The compound occurs as a tetrahydrobiopterin in the liver in a concentration of about 75 μg; biopterin exists only in trace amounts. After fractional centrifugation of liver homogenate, approximately 90% of tetrahydrobiopterin is contained in the supernatant fraction.

The possibility of inhibiting erythronolide (lactone of erythromycin) biosynthesis with fluoropropionic acids without affecting the synthesis of the sugars of erythromycin was investigated, α- or β-fluoropropionic acid and their ethyl esters were tested for their ability to inhibit erythromycin production in S. erythreus. Ethyl-β-fluoropropionate (ethyl-β-F) was the best inhibitor of the 4 compounds tested. When the concentration of ethyl-β-F in the medium was 6,5 × 10 -3 -m. erythromycin formation was inhibited to about 95—98% while the volume of the mycelium decreased by only 5 percent. The hyphae of the organism grown in the presence of the inhibitor were shorter and thicker than those of the cells grown in the control medium. No accumulation of nucleotide-bound cladinose, mycarose, desosamine or 4-keto-6-deoxyintermediates could be found in the inhibited cultures. In the presence of ethyl-β-F the accumulation of an unknown substance was observed, which is probably an aliphatic acid.

Aus dem Kulturfiltrat von Mycobacterium bovis Stamm BCG wird neben Nicotinsäure eine weitere Bromcyan-positive Substanz isoliert und als 3-Hydroxymethylpyridin identifiziert. Dieses Pyridin-Derivat läßt sich auch als Ausscheidungsprodukt anderer Mycobakterien-Arten nachweisen. 3-Hydroxymethylpyridin ist eng mit dem Stoffwechsel der Nicotinsäure verbunden. Angebotene Nicotinsäure wird von den BCG-Bakterien aufgenommen und zu 3-Hydroxymethylpyridin umgewandelt.

Two isomers, a and b, of the tetracarbonic acid and some tri-, di- and monocarbonic acids, all derived from cobyric acid, have been crystallized. Two cobinamide monocarbonic acids have also been crystallized. The two crystalline tetracarbonic acids are both stable at 20 °C. They differ from each other in crystal shape. Some anions, carbon monoxide and light catalyze their thermal isomerisation in aqueous medium. The equilibrium a ⇄ b depends upon the pH of the medium only. At pH < 2.5 more than 53% and at pH >4.5 about 20% of the tetracarbonic acid is in the a-form (b = 100—a). The equilibrium shifts therefore as the carboxyls of the tetracarbonic acid (pK=3.15 and 3.85) dissociate. The shift probably results from the action of the newly formed carboxylate anions, which accelerate the reaction (a ⇄ b) in the direction a → b. The isomerisation reaction is slower in more dilute solutions. The 14 CN group of the tetracarbonic acid undergoes thermally dependent exchange with the CN group of the cobyric acid. This intermolecular exchange and the isomerisation are perhaps analogous reactions, resembling the formation of cyanocobalamin from aquocobalamin and cyano-aquocorrinoids. The two forms, a and b, of tetracarbonic acid, cobyric acid, cobinamide phosphoric acid and cobinamide differ slightly in their absorption and CD spectra. On the basis of these results it is probable that the CN group of the tetracarbonic acid is bound “above” (in the b-form) or “below” (in the a-form) the plane of the corrin ring and that the CN ligand migrates during a collision of two molecules of tetracarbonic acid. The anion- and light-catalysed isomerisation reactions are probably results of heterolysis and homolysis of the Co — CN bond, respectively.

Disruption of four different influenza viruses (strains A/PR8, A 1 /Ann Arbor/1/57, A 2 /Japan/170/62 and B/Maryland 1/59) by Tween-ether or sodium deoxycholate leads to polydisperse populations of strain-specific immunoprecipitating antigens which occur both associated with or separately from hemagglutinins and which seem to be heterogeneous with respect to antibody binding sites. Besides yielding hemagglutinins with a sedimentation coefficient of about 70 s, Tween-ether treatment also yields smaller 9 s antigens. A similar antigen is released from A/PR8 virus by trypsin treatment. Treatment of the B/Maryland/1/59 virus with sodium deoxycholate results in the release of a 9 s precipitating antigen, but more rapidly sedimenting antigens are obtained with the other virus strains.

Während der Fütterung von Diäthylnitrosamin kommt es zu Beginn in der Leber zu einem Anstieg der Folatreduktaseaktivität, der nach Absetzen des Carcinogens reversibel ist. Nach dem Auftreten sog. kleinzelliger Nester sinkt die Aktivität ständig und erreicht im Carcinomgewebe Werte, die deutlich unter den Normalwerten liegen.

In the yellow cells of brown trout (Salmo trutta forma fario L.) and rainbow trout (Salmo irideus GIBBONS) there are pigment particles, which differ in form and colour: yellow grains, yelloworange drops, and purple needles. The yellow colour of the grains is caused by Sepiapterin (Dihydrobiopteridin-derivative), which, as well as the corresponding Tetrahydrobiopteridin-derivative and Ichthyopterin (7-Hydroxybiopteridin), could be shown in the skin of trouts. A fat-soluble carotenoid, Astaxanthin (3,3′-dihydroxy-4,4′-dioxo-β-carotin), produces the colour of the orange drops and of the purple crystalline needles. The carotenoid level of the yellow cells depends on the carotenoid amount of the food.

The biosynthesis of the anthraquinones, alizarin I and purpurin II, in Rubia tinctorum (madder) has been investigated. Acetate- [2- 14 C] proved to be a precursor only of ring C and in part of the keto groups of the quinone ring. While phenylalanine- [U- 14 C] was not incorporated into I and II, shikimic acid was found to be a good precursor of these compounds. The radioactivity of shikimic acid-[1,2- 14 C] could be localized only in ring A; shikimic acid-[U- 14 C] however was incorporated in toto; the ring being transformed into ring A of the anthraquinone, and the carboxyl group of this acid into one of the keto groups of ring B. These findings demonstrate the existence of a biosynthetic pathway for the formation of anthraquinones in Nature, which is entirely different from the polyacetate route.

The carotenoids of the Vaucheriales Vaucheria and Botrydium have been investigated. Both contain the same pigments β-carotene, cryptoxanthinepoxid (traces), zeaxanthin (traces), antheraxanthin, a new xanthophyll named vaucheriaxanthin with three esterified hydroxyls and another unknown pigment. The carotenoids of the Vaucheriales seem to be not identical with the carotenoids of the other Xanthophyceae investigated by THOMAS and GOODWIN 8 . The identity of pigment composition of Vaucheria and Botrydium underlies their close relationship in the algal system. The significance of these pigments is discussed. Diatoxanthin, a pigment of diatoms, is identical with antheraxanthin.

The light-dependent Cl ⊖ uptake in Elodea densa exhibits dual DCMU inhibition curves dependent on the presence and absence of CO 2 . This suggests that cyclic photophosphorylation (energy surce in the absence of CO 2 ) is also inhibited by higher concentrations of DCMU in vivo. Further, at low DCMU concentrations the Cl ⊖ uptake in the presence of CO 2 is much smaller than would be expected if cyclic photophosphorylation were operative. This points to a parallel inhibition of non-cyclic and cyclic photophosphorylations by low concentrations of DCMU in the presence of CO 2 . The apparent inhibition of cyclic photophosphorylation at low concentrations of DCMU can be reversed by withdrawal of CO 2 . It is concluded that CO 2 may be important in the regulation of cyclic and non-cyclic photophosphorylations in vivo.

The isolation and purification of RNA polymerase from the blue-green alga Anacystis nidulans is described. The method consists in an initial fractional centrifugation which yields 60 — 70% of the enzyme associated with a DNA-rich fraction. It is subjected to column chromatography (DEAE-cellulose) and gel filtration (Sephadex G-200) to obtain a 110 —120 fold increase in specific activity over the crude extract. The preparation is free from polynucleotide phosphorylase, kinases, phosphatases and nucleic acids. The enzyme requires DNA, a primer, as well as Mg 2⊕ , Mn 2⊕ and the 4 ribonucleoside triphosphates for the net synthesis of polyribonucleotides. Salmon sperm DNA and native DNA from Chlorella pyrenoidosa can replace Anacystis DNA as primer. The properties of the product, however, depend to a certain extent on the primer DNA used as revealed by column chromatography of the former on methylated serum albumin. After isolation by this method, the synthesized polyribonucleotides were found to be partially stable against the action of RNase. This finding suggests a possible association of the newly synthesized RNA with the primer DNA in form of a stable complex which may function as an intermediate of the DNA directed RNA synthesis.

The exchange of tissue water of corn roots with ambient water was investigated using D 2 O, a gaschromatographic method, and a technique which avoids prolonged contact of tissue water with atmospheric water. The exchange experiments were performed at 10°, 20°, and 25 °C and the activation energies for different exchange phases were calculated by a method involving a graphical determination of the relative exchange rates at certain H 2 O/D 2 O gradients. Log 10 of the rates were plotted versus 1/T as usual and the activation energies were calculated from the slopes of the straight lines. The energy of activation of the exchange process increased from 4.4 kcal-mol -1 in an initial phase (exchange of surface water and free space water) to 6.3 kcal·mol -1 in later phases which represent the processes of permeation through plasma and plasma membranes. This suggests that the hydrogen bonds of permeating water have a mean energy of 6 —7 kcal·mol -1 resulting from interaction with membrane (and plasma) constituents. The theory is proposed that cell membranes contain water phases with hydrogen bonds stronger than those in pure liquid water. These water phases are assumed to be located mainly within apolar portions of globular membrane proteins. Not solely a continous lipid layer, but a specific arrangement of polar and apoiar portions of globular membrane proteins is regarded to be essential for semipermeability and other membrane properties. Results from various authors were considered in establishing the general working hypothesis that agents like apoiar compounds which increase water structure decrease water permeability, and agents like salts which disrupt water structure increase water permeability.