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1968 (403)
41Author    HansFriedrich Eicke, Jürgen KnoopRequires cookie*
 Title    Konduktometrisdie Analyse der Adduktbildung binärer Gemische von 1.2-Dithia-cyclopenten-onen-(3) und -thionen-(3) in Benzol  
 Abstract    The formation of adducts of some 1,2-dithiacyclopenten-ones-(3) and -thiones-(3) as well their binary mixtures in benzene and cyclohexane resp. has been investigated by measurements of the apparent conductivity and molar polarization. A theory based on simple assumptions describes reasonable well the experimental run of the apparent conductivity of these binary mixtures. In addition these assumptions might give some hints on a possible mechanism of the charge production. 
  Reference    (Z. Naturforschg. 23b, 165—173 [1968]; eingegangen am 26. Mai 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0165.pdf 
 Identifier    ZNB-1968-23b-0165 
 Volume    23 
42Author    D. Biedenkapp, Alarich WeissRequires cookie*
 Title    Kernquadrupolresonanz(KQR)-Spektroskopie an 35 C1 in Komplexverbindungen * von Arsentrichlorid, AsCl 3 , mit einigen aromatischen Kohlenwasserstoffen  
 Abstract    By measuring the 35 C1 nuclear quadrupole resonance (NQR) spectra it is shown that ASC13 , like SbCl 3 , is able to form crystalline complex compounds with aromatic hydrocarbons. Investiga-tion of the freezing-point diagrams reveal the existence of the following compounds: 2 AsCl 3 • C6H6; 
  Reference    (Z. Naturforschg. 23b, 174—177 [1968]; eingegangen am 29. Juni 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0174.pdf 
 Identifier    ZNB-1968-23b-0174 
 Volume    23 
43Author    D. Gröger, D. Erge, H. G. FlossRequires cookie*
 Title    Über die Herkunft der Seitenkette im d-Lysergsäure-methylcarbinolamid  
 Abstract    Using a strain of Claviceps paspali Mar 488 it has been shown that alanine-2-C 14 is incorporated with high efficiency in the carbinol amide moiety of D-Lysergic acid-a-hydroxyethylamide=II. After feeding of DL-alanine-15 N, DL-aspartic acid-15 N and L-glutamine-CO-15 NH 2 the highest specific incor-poration rate was observed with DL-alanine-15 N. Short term experiments with D,L-alanine-15 N revealed, that the greater part of the 15 N-excess is localized in the N-atom of the side-chain of II. The carbinolamide moiety of the isolated alkaloid arises probably from alanine or a closely related compound. 
  Reference    (Z. Naturforschg. 23b, 177—180 [1968]; eingegangen am 24. Mai 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0177.pdf 
 Identifier    ZNB-1968-23b-0177 
 Volume    23 
44Author    Gerold AdamRequires cookie*
 Title    I. Ionenstrom nach einem depolarisierenden Sprung im Membranpotential  
 Abstract    The presently accepted theory of nerve excitation (HODGKIN and HUXLEY, 1952) fails to explain the mechanism of regulation of the state of the axon membrane by the membrane-potential or the cation-activities. We have proposed a physico-chemical mechanism for the regulation of the excitation state based on a model of the axon membrane as a two-dimensional cooperative cation exchanger in contact with the electrolyte reservoirs inside and outside. In the resting state, the lattice units of the cation exchanger bind calcium ions. Upon depolari-zation or decrease of the calcium activity in the outside medium, the resting state becomes instabil and univalent cations are bound by the lattice units. The ion movements accompanying the cation exchange give rise to the inward excitation current, as observed in a voltage clamp experiment. This cooperative cation-exchange can be considered as a two-dimensional phase transition. Its kinetics have been described by the processes of nucleation and nucleus-growth. The kinetic theory has been applied to measurements of the ionic current in the voltage clamp experiments of COLE and MOORE (1960). The theory describes in good agreement with the experiment the dependence of the ionic current on time and on membrane potential for small depolarizations. Three parameters have to be adjusted in this comparison, two of which have a simple molecular meaning and are given as: a 0 = 21 X21 A 2 = area per lattice unit M; = 5.1 Kcal/mol=twice the difference in interaction energy of a lattice unit in the two binding states with the rest of the lattice being in one of the two states. The order of magnitude of these parameters favours the hypothesis of identifying the excitable structural units in the axon membrane with membrane-bound proteins. 
  Reference    (Z. Naturforschg. 23b, 181—197 [1968]; eingegangen am 26. Juni 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0181.pdf 
 Identifier    ZNB-1968-23b-0181 
 Volume    23 
45Author    K. F. AepinusRequires cookie*
 Title    Einwirkung von Ribonuclease, Trypsin und a-Chymotrypsin auf in vitro neugebildete Leberpolysomen  
 Abstract    Frisch präparierte und in vitro neugebildete Polyribosomen werden 10 min bei 22 °C der Ein-wirkung von RNase, Trypsin und a-Chymotrypsin unterworfen. Die frisch präparierten Polysomen werden durch RNase und Trypsin in die 78 S-und 105 S-Einheiten zerlegt. In vitro neugebildete Polysomen werden nur durch Trypsin angegriffen. a-Chymotrypsin zeigt sowohl bei den frisch präparierten als auch bei den in vitro neugebildeten Polysomen keinen Effekt auf die Verteilung der Polysomen im Saccharose-Dichtegradienten. Ein Einfluß der nascierenden Peptidketten auf die Polysomenstruktur wird nicht gefunden. Eine Stabilisierung der mRNS durch basisches Protein wird angenommen. 
  Reference    (Z. Naturforschg. 23b, 198—203 [1968]; eingegangen am 24. Februar 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0198.pdf 
 Identifier    ZNB-1968-23b-0198 
 Volume    23 
46Author    K. F. AepinusRequires cookie*
 Title    In vitro-Neubildung von Leber-Polyribosomen in Gegenwart von Leberzellkern-Fraktion  
 Abstract    Bei der in vitro-Proteinsynthese mit pH 5-Überstand, tRNA und Cysteamin an Leber-Polyribo-somen wird in Gegenwart von Leberzellkern-Fraktion eine Neusynthese von Polyribosomen beob-achtet. Ein Ubertritt der Orotsäure-6-14 C in vivo markierten mRNS und des 3 H-1-Arginin markier-ten Kernprotein vom Kern auf die Ribosomen bzw. Polysomen kann gezeigt werden. Polyribosomen, die vor der in vitro-Proteinsynthese 10 min bei 35 °C erwärmt werden, zeigen eine verminderte An-lagerung von mRNS und Kernprotein und eine Reduzierung der Proteinsynthese. Die Diskussion ergibt, daß eine Stabilisierung der mRNS durch Kernprotein angenommen werden kann. 
  Reference    (Z. Naturforschg. 23b, 203—210 [1968]; eingegangen am 24. Februar 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0203.pdf 
 Identifier    ZNB-1968-23b-0203 
 Volume    23 
47Author    H. Iwainsky, H. Reutgen, R. KalichRequires cookie*
 Title    2. Mitt.: Über den Einfluß von Fermentinhibitoren und antituberkulös wirksamen Stoffen auf den 32 P-Einbau  
 Abstract    1. Der Einfluß von Fermentinhibitoren auf den 32 P-Einbau in Mykobakterien unter Bedingungen der endogenen Atmung wird untersucht. 2. Arsenat stimuliert bei niedrigen Inhibitor-Konzentrationen den 32 P-Einbau. Bei Erhöhung der Hemmstoffkonzentration wird die Incorporation des radioaktiven Isotopes durch die untersuchten Fermentinhibitoren gehemmt. 3. Ähnliche Ergebnisse werden auch beim Einsatz von antituberkulös wirksamen Stoffen erhal-ten. So bewirken z. B. niedrige Konzentrationen von Äthioniamid eine Stimulierung, höhere Kon-zentrationen eine Hemmung des Einbaues. 4. Für Isoxyl läßt sich eine eindeutige Wirkung nachweisen. Sie entspricht in ihrer Beziehung zur Konzentration der des Äthioniamides. Die Wirkung von Ethambutol ist abhängig von der Ineu-bationsdauer. 5. Sensible und resistente Bakterien verhalten sich unterschiedlich gegenüber dem die Resistenz verursachenden Mittel. Der 32 P-Einbau in die resistente Population wird kaum beeinflußt. 6. Auf Grund dieses Verhaltens wird eine Differenzierung zwischen sensiblen und resistenten Keimen versucht. Die optimalen Reaktionsbedingungen werden festgelegt. 7. Die für INH und Sm erhaltenen Ergebnisse werden denen gegenübergestellt, die mit mikro-biologischen Verfahren erhalten wurden. Das Verfahren wird zur raschen Resistenzbestimmung vor-geschlagen. 
  Reference    (Z. Naturforschg. 23b, 211—216 [1968]; eingegangen am 26. Juni 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0211.pdf 
 Identifier    ZNB-1968-23b-0211 
 Volume    23 
48Author    I. Miller, R. Plapp, 0. KandlerRequires cookie*
 Title    Isolierung und Identifizierung eines serinhaltigen UDP-muramyl-tripeptides aus Butyribacterium rettgeri  
 Abstract    An UDP-activated murein precursor was isolated from Butyribacterium rettgeri after one hour inhibition by D-cycloserine. The compound contains UDP, muramic acid, L-serine, D-glutamic acid and L-ornithine in equimolar amounts. The amino acid sequence of the tripeptide attached to mur-amic acid is L-Ser-D-Glu-L-Orn as determined by end group analysis and identification of peptides obtained after partial hydrolysis. As shown by the identification of glutamic acid -y-hydrazid after hydrazinolysis of the compound, ornithine is bound by its a-amino group to the y-carboxyl group of glutamic acid. The amino acid sequence of the precursor is in agreement with the structure of the corresponding part of the whole murein of Butyribacterium rettgeri, as proposed recently. 
  Reference    (Z. Naturforschg. 23b, 217—220 [1968]; eingegangen am 16. Mai 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0217.pdf 
 Identifier    ZNB-1968-23b-0217 
 Volume    23 
49Author    H. H. Stiehl, H. T. WittRequires cookie*
 Title    Die kurzzeitigen ultravioletten Differenzspektren bei der Photosynthese  
 Abstract    Plastoquinone PQ is engaged in photosynthesis 1 . Difference spectra in the UV-region indicate that PQ is an intermediate in the electron transport chain 2 . PQ is located as a pool between the two light reactions I and II 3 . PQ is reduced by hv\\ and oxidized by hv\ 3 . In this paper the dif-ference spectra which occur during light excitation of spinach chloroplasts and chlorella vulgaris were measured in the UV-region with high resolution by the high sensitive method of periodical flash photometry 6 . On excitation with long flashes (10 -1 sec) the difference spectra are similar to those obtained when plastoquinone is reduced to hydroquinone in vitro (see figs. 1, 3 and 6). Deviations in the case of chlorella (fig. 4) are caused by additional NADP-reduction. After extraction of plasto-quinone from chloroplasts the difference spectra do not occur during light excitation but they can be produced in full after reconstitution with synthetic plastoquinone A (see fig. 2). In the presents of far red background light (718 nm) which excites only light reaction I the magnitude of the spectrum is doubled (see fig. 3). By excitation with short flashes (10 —5 sec), two different spectra were found. The difference spectrum with a life-time of 5-10 _4 sec (fig. 7) is new and does not correspond to that of plasto-quinone in vitro. The difference spectrum with a life-time of about 2 • 10~ 2 sec (fig. 5) corresponds to the plastoquinone reduction. The magnitude of this spectrum is ten times smaller than that ob-tained by excitation with long flashes (fig. 6). The 1:10 ratio of the magnitude of the spectra in short and long flashes can be interpreted by a pool of plastoquinone between the two light reactions with a dynamic capacity of ten electrons. The doubled magnitude of the spectra in far red background light can be interpreted by an elec-tron acceptor pool for plastoquinone with a capacity of five electrons (see also the following papers). Die Beteiligung von Plastochinon PQ an der Photosynthese wurde von BISHOP nachgewiesen 1 . Durch Messung kurzzeitiger Absorptionsänderungen im ultravioletten Spektralbereich wurde an Chloro-plastenbruchstücken gezeigt, daß PQ an einer Redox-reaktion in der Elektronentransportkette der Primär-vorgänge beteiligt ist 2 . Später wurden solche Ab-sorptionsänderungen auch an ganzen Chlorellazellen 
  Reference    (Z. Naturforschg. 23b, 220—224 [1968]; eingegangen am 11. Juli 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0220.pdf 
 Identifier    ZNB-1968-23b-0220 
 Volume    23 
50Author    P. Schmidt-Mende, B. RumbergRequires cookie*
 Title    Zur Plastochinonreduktion bei der Photosynthese  
 Abstract    The absorption changes at 254 nm which are coupled with the formation of plastohydroquinone (PQ =) depend strongly on the intensity and duration of the actinic light (fig. 2). At an intensity of 10 6 erg-sec -1 -cm -2 and a duration of 0,1 sec, maximal reduction is obtained. The reduction of chlorophyll-ai ° was followed by absorption changes at 703 nm. From the changes at 254 and 703 nm (fig. 3 and tab. 1) follows: PQ=:Chl-ai = 5:1 (with As = 1,3-10 4 MMol^-cm -1 for PQ at 254 nm and As = 3,6 • 10 4 Z-Mol -1 -cm -1 for Chl-ai at 703 nm). This value corresponds to a pool of plastoquinone with a dynamic capacity of ten electrons. This value is exactly the same as that which was derived in another way in the preceding paper 3 . The time course of the reduction of plastoquinone is given by an exponential function (figs. 4 and 5) with a rate constant for the reduction k/ = 35 sec -1 at 25 °C. Together with the rate constant for the reoxidation (k 2 ' = 11 sec -1 , see next paser 6), it follows for the total photochemi-cally engaged plastoquinone PQ 0 : Chl-ai = 6.5 : 1. 1. Reduktion des Plastochinon in Abhängigkeit von der Belichtungsintensität und der Belichtungsdauer 
  Reference    (Z. Naturforschg. 23b, 225—228 [1968]; eingegangen am 11. Juli 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0225.pdf 
 Identifier    ZNB-1968-23b-0225 
 Volume    23 
51Author    P. Schmidt-Mende, H. T. WittRequires cookie*
 Title    Zur Plastochinonoxydation bei der Photosynthese  
 Abstract    After the reduction of PQ in the light, PQ = is oxidized in the dark. Three types of reoxydation can be distinguished in isolated chloroplasts of spinach: a) Without addition of an electron acceptor: No reoxidation can be observed (fig. la), b) With addition of an electron acceptor: 50% is reoxidized (fig. lb), c) With addition of an electron ac-ceptor and permanent far red background light (718 nm) 50% is reoxidized as in b, the other 50% are oxidized in a second phase (see fig. 1 c). This second phase depends on the intensity of the far red background light (figs. 4 and 5). 
  Reference    (Z. Naturforschg. 23b, 228—235 [1968]; eingegangen am 11. Juli 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0228.pdf 
 Identifier    ZNB-1968-23b-0228 
 Volume    23 
52Author    J. WeikardRequires cookie*
 Title    Cytochrom-b-563 als natürlicher Elektronenüberträger in einem zyklischen Elektronentransport der Photosynthese  
 Abstract    By excitation of spinach chloroplasts with flashes (5-10 _5 sec) of far red light hv\ (A = 728 nm) and with addition of 2-10~ 4 M/Z benzylviologen as electron acceptor irreversible absorption changes are observed as depicted in fig. 1 top. With 10~ 3 M/Z K3Fe(CN)6 as electron acceptor irreversible changes are observed as depicted in fig. 1 bottom. The difference of the spectra in fig. 1 is presented in fig. 2. Fig. 2 corresponds to the spectrum which is caused by reduction of a cytochrome-b-563. Thus excluding K3Fe(CN)6 as electron acceptor cytochrome-b-563 can be reduced by hvi (A=728nm). A re-oxydation occurs by red light hv\i (Ä = 663nm), s. figs. 3, 4. These results demonstrate a natural cyclic flow of electrons including both light reactions Chl-ai and Chl-au (s. fig. 6). The results are reviewed in 1. c. 10 . 
  Reference    (Z. Naturforschg. 23b, 235—238 [1968]; eingegangen am 24. Juli 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0235.pdf 
 Identifier    ZNB-1968-23b-0235 
 Volume    23 
53Author    B. Rumberg, U. SiggelRequires cookie*
 Title    Quantitative Zusammenhänge zwischen Chlorophyll-b-Reaktion, Elektronen- transport und Phosphorylierung bei der Photosynthese  
 Abstract    Carefully prepared spinach chloroplasts show the slow phase (half life 20 —500 msec) of the ab-sorption changes of Chlorophyll-b only. The decay of the absorption changes is an exponential one (fig. 1, fig. 5, eq. 1). The decay time as well as the electron transport rate are changed by coupling and uncoupling phosphorylation. A. By addition of the phosphorylation uncoupler methylamine hydrochloride the decay is accelerated up to ten times from 500 msec to 50 msec at pH = 7,4 and 20 °C (fig. 1, table 1). At the same time the electron transport rate measured by the reduction of ferricyanide increases ten times (table 1). Reciprocal decay time and electron transport rate are always proportional to each other (fig. 2, eq. 2). Phosphorylation uncouplers as carbonyl cyanide phenylhydrazone, atebrin, and dichlorphenol indo-phenol accelerate the decay of the Chl-b absorption changes as well (fig. 3). B. Phosphorylation accelerates the decay time of the Chl-b absorption changes up to two times from 90 to 40 msec at pH = 8,4 and 20 °C (fig. 4, fig. 5, table 2). At the same time the electron transport rate too increases two times, thus reciprocal decay time and electron transport rate are proportional to each other again (fig. 6, table 2). The same result is obtained when phosphorylation is suppressed by omission of phosphate or addition of phlorizin (fig. 6, fig. 7 top). It is shown that the phosphoryla-tion rate is identical with the extra electron transport rate stimulated by phosphorylation as measured by IZAWA et al. 18 (fig. 7 bottom). At the same time it is shown that phosphorylation is proportional to the change in the reciprocal decay time of the Chl-b absorption changes (fig. 7 bottom, eq. 3). 
  Reference    (Z. Naturforschg. 23b, 239—244 [1968]; eingegangen am 21. August 1967) 
  Published    1968 
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 Identifier    ZNB-1968-23b-0239 
 Volume    23 
54Author    W. Junge, H. T. WittRequires cookie*
 Title    On the ion transport system of photosynthesis — Investigations on a molecular level * —  
 Abstract    1. The Chl-b reaction in chloroplasts is biphasic. 2. Both the slow phase 10~ x sec) and the fast phase 10 _1 sec) are caused by ion ex-change across the thylakoid membrane. 3. The slow phase is caused by an intrinsic slow ion exchange (H®) across an undamaged membrane (The permeability for arbitrary ions is lower than for H®). 4. The fast phase is caused by an enhanced ion exchange across a damaged membrane. Damag-ing can be systematically caused, for instance, by membrane holes made by osmotic procedures, or by specific pores for alkaline ions made by gramicidin. 5. The function unit of the intrinsic slow ion exchange (H®) has been identified as being the membrane of one whole undamaged thylakoid. 6. The electron transport in undamaged thylakoid membranes is coupled to the intrinsic ion transport (H®). 7. Phosphorylation is coupled to an additional intrinsic ion transport (H®). 8. Leaks of the order of only one pore cause a collapse from the intrinsic slow phase (10sec) into the fast phase of ion exchange (< 10sec). 9. The ratio of the amplitude of the slow and fast phases indicates the ratio of thylakoids which are undamaged and damaged. 10. The Chl-b reaction indicates an electrical field across the thylakoid membrane. This field promotes the ion exchanges discussed above. 11. The potential difference amounts to about 250 mV. 12. The field is built up in light within < 2 • 10" 8 sec 29 > 30 . 13. These results give a first direct insight into the properties of membranes on a molecular level. They serve as a valuable means for deciding between the different hypotheses on the mechanism of phosphorylation. 1. Connection of the Chlorophyll-b reaction with the primary events in photosynthesis 
  Reference    (Z. Naturforschg. 23b, 244—254 [1968]; eingegangen am 21. August 1967) 
  Published    1968 
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 Identifier    ZNB-1968-23b-0244 
 Volume    23 
55Author    Martin Wenzel, Dagmar EissnerRequires cookie*
 Title    Die Verteilung 51 Cr-markierter Clostridien-Sporen in Tumor-tragenden Ratten  
 Abstract    Tumorgewebe wird mangelhaft mit Sauerstoff versorgt. Bei der i. v. Injektion von anaerob aus-keimenden Sporen von Clostridium butyricum finden daher die Sporen nur im Tumorgewebe einen geeigneten Nährboden. Mit Hilfe Tumor-tragender Ratten wurde daher untersucht, ob bei der i. v. Injektion von 51 Cr-markierten Sporen sich eine bevorzugte Sporen-und damit Aktivitätsanreicherung im Tumorgewebe im Vergleich zum Normalgewebe feststellen läßt. Entsprechende Verteilungsstudien wurden in vivo durch Szintigraphie und nach Töten der Versuchstiere durch Aktivitätsmessung in den einzelnen Organen ausgeführt. Die Ergebnisse zeigen eine bevorzugte Aktivitätsanreicherung im RES. Der zentrale nekrotische Bereich der Tumoren besaß eine erhöhte spezifische Aktivität gegenüber den Tumorrandgebieten. 
  Reference    (Z. Naturforschg. 23b, 255—258 [1968]; eingegangen am 21. Juni 1967) 
  Published    1968 
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 Identifier    ZNB-1968-23b-0255 
 Volume    23 
56Author    E. Leistner, M. H. ZenkRequires cookie*
 Title    Zur Biogenese von 5-Hydroxy-1.4-naphthochinon (Juglon) in Juglans regia L  
 Abstract    The biosynthesis of 5-hydroxy-l,4naphthoquinone (juglone) was studied by supplying radio-active precursors to leaves of Juglans regia plants. A chemical degradation of the juglone molecule was devised (Fig. 1). With these methods it was shown that the ring atoms of shikimic acid are incorporated into the benzene ring of the quinone, while the carboxyl group of this acid is trans-formed to 50% into each of the keto groups of the quinone ring (C-atoms 1 and 4 of juglone. Tab. 3). This suggested a symmetrical molecule to be an intermediate in the formation of juglone — most probable 1,4-naphthoquinone. This compound was synthetized with 14 C in the positions 2, 3, 9, and 10 and was found to be a good precursor of juglone in Juglans as well as for 2-hydroxy-l,4-naphthoquinone in Impatiens plants (Tab. 4). 3,4-Dihydroxybenzaldehyde (Tab. 2) and chorismic acid (Tab. 7) which have been suggested previously as intermediates in the bio-synthesis of naphthoquinones are no precursors of juglone. The source of three carbon atoms of the quinone nucleus remains to be determined; one or two of these carbon atoms (C2 and/or C3 of juglone) are formed from the methylen carbon of malonate (Tab. 5 and 6); surprisingly, however, the carboxyl carbons of malonic acid are not incorporated. The substitution of shikimic acid oc-cures in the position 6 of this acid as could be judged from the degradation of juglone labelled with shikimic acid [1,2-14 C] (Fig. 2; Tab. 3). 1,4-Naphthoquinone (or naphthohydroquinone) is postulated as an important intermediate in the biosynthesis of naphthoquinone derivatives in higher plants. 
  Reference    (Z. Naturforschg. 23b, 259—268 [1968]; eingegangen am 7. Juli 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0259.pdf 
 Identifier    ZNB-1968-23b-0259 
 Volume    23 
57Author    D. WernerRequires cookie*
 Title    Stoffwechselregulation durch den Zellwandbaustein Kieselsäure: Polgrößenänderungen von a-Ketoglutarsäure, Aminosäuren und Nucleosidphosphaten  
 Abstract    When the centric diatom Cyclotella cryptica is grown in a Si(OH)4-free medium, the glutamic acid pool decreases within 3 hours to a third of the original value, whereas the aspartic acid pool is reduced by only about 20 per cent. The pools of nucleosid-triphosphates and of glycerol-l-phos-phate remain unaffected during this time. The nucleosid-diphosphates pool decreases in the same way as that of aspartic acid. The decrease in the glutamic acid pool precedes the inhibition of total protein synthesis in Si (OH) 4 -deficient cells, and a significant decrease in the a-ketoglutarate pool precedes the decrease of the glutamic acid content. Already within 60 minutes öfter incubation in a Si(OH)4-free medium, the content of a-ketoglutarate is decreased to one third of the normal value. On the other hand, the acetyl CoA pathway (enhanced fatty acid synthesis) is not inhibited. The results suggest, that the Si (OH) 4-metabolism interferes with reactions between the condensing enzyme (acetyl-CoA and oxalacetate) and a-ketoglutarate. The delay between inhibition of pro-tein* and RNA-synthesis and the different changes in the pools of amino acids and nucleosid-tri-phosphates resemble the regulation of the nucleosid-triphosphate pool and RNA-synthesis in amino acid starved strains of E. coli (EDLIN and NEUHARD) though the primary causes are quite dif-ferent. 
  Reference    (Z. Naturforschg. 23b, 268—272 [1968]; eingegangen am 13. Juni 1967) 
  Published    1968 
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 Identifier    ZNB-1968-23b-0268 
 Volume    23 
58Author    WernerW. Franke, Heinz FalkRequires cookie*
 Title    Enzymatisch isolierte Cellulose-Fibrillen der Valonia-Zellwand  
 Abstract    Cellulose microfibrils from the cell wall of the green alga Valonia macrophysa were isolated by enzymatical digestion of the wall matrix and examined in the electron microscope using the negative staining technique. The smallest fibrils obtained after prolonged treatment were found to be flat ribbons with a width about 10—20 nm and a height of 3 to 4 nm. This result is discussed in relation to F r e y -W y s s 1 i n g's concept of an "elementary fibril" with a cross-section of 3.5X3.5 nm. Some alternation of unstained areas along the fibrils was observed. This was interpreted as artificially induced rather than relating to the structure and the arrangement of the cellulose chain molecules. 
  Reference    (Z. Naturforschg. 23b, 272—274 [1968]; eingegangen am 21. Juni 1967) 
  Published    1968 
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 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0272.pdf 
 Identifier    ZNB-1968-23b-0272 
 Volume    23 
59Author    M. Correa, H. Hunger, NollerRequires cookie*
 Title     
 Abstract    Die Eliminierungs-Reaktionen von 2-Chlorpropan und 2-Chlor-2-D-Propan an den Katalysatoren MgS04, CaS04 und BaS04 (11 Stdn. bei 150 °C unter 1 mm Hg Luft vorbehandelt) wurden mikrokatalytisch und mas-senspektrometrisch untersucht (Katalysatorenvolumen: ca. 1,5 cm 3 Pulver; Trägergas: Helium; Strömungsge-schwindigkeit: 60 ml/min; Massenspektrometer: CEC 21-620). 
  Reference    (Z. Naturforschg. 23b, 275 [1968]; eingegangen am 21. Oktober 1967) 
  Published    1968 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0275a_n.pdf 
 Identifier    ZNB-1968-23b-0275a_n 
 Volume    23 
60Author    M. Correa, H. Hunger, NollerRequires cookie*
 Title     
 Abstract    Die Eliminierungs-Reaktionen von 2-Chlorpropan und 2-Chlor-2-D-Propan an den Katalysatoren MgS04, CaS04 und BaS04 (11 Stdn. bei 150 °C unter 1 mm Hg Luft vorbehandelt) wurden mikrokatalytisch und mas-senspektrometrisch untersucht (Katalysatorenvolumen: ca. 1,5 cm 3 Pulver; Trägergas: Helium; Strömungsge-schwindigkeit: 60 ml/min; Massenspektrometer: CEC 21-620). 
  Reference    (Z. Naturforschg. 23b, 275 [1968]; eingegangen am 21. Oktober 1967) 
  Published    1968 
  Similar Items    Find
 DEBUG INFO      
 TEI-XML for    default:Reihe_B/23/ZNB-1968-23b-0275b_n.pdf 
 Identifier    ZNB-1968-23b-0275b_n 
 Volume    23 
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