bluuebunny/crossref_metadata_2025 huggingface dataset:
On the Mechanism of Electric Response of the Photoreceptors of the Barnacle and Other Animals
Authors: Krischer Christof C.
Published: February 2015

For the barnacle photoreceptors it is estimated that at 20°C a half-maximal flash response requires the photic activation of 1% of the tubulous microvilli. The decrease of photo-electric efficiency at high intensities and low temperature is attributed to less efficient 2 quantum activation of microvilli. The estimate of the light induced charge flux yields evidence for ionic depletion in an extracellular space which is restricted by glia cells. The integration of the current during the transient of the response to steps of intense light yields limits for the extracellular volume which are in accord with electron microscopic results. The observed reaction scheme with a ratio of latency time : duration of response : adaptation time independent of temperatur and type of photoreceptor is in a model explained with the same transfer processes occuring in volume elements of different size. A brief review of photoreceptors of other animals shows that in spite of different durations of the responses the reaction scheme of flash responses and the photo-electric efficiency (≈ 105 ions per absorbed photon) are similar for different photoreceptors.
Enzymes as Markers in Virus Preparations
Authors: Drzeniek Rudolf , Kaluza Georg
Published: February 2015

Acid phosphatase and 5′-nucleotidase activity, present in fowl plague virus preparations, is separated from virus particles by a two-step sucrose gradient centrifugation. These enzymes may therefore be used to define the degree of purity of myxovirus preparations. ATPase activity, however, was found to be associated with virions of fowl plague.
Photosystem I-abhängige Phosphorylierung isolierter Chloroplasten mit Ascorbat/2.6-Dichlorphenolindophenol als Elektronendonator und Methylviologen als Elektronenakzeptor / Photosystem I Dependent Phosphorylation of Isolated Chloroplasts with Ascorbate/2,6-Dichlorophenolindophenol as Electron Donor and Methylviologen as Electron Acceptor
Authors: Strotmann Heinrich , Von Gösseln Christa
Published: February 2015

Photosystem I related phosphorylation of isolated chloroplasts was investigated with special reference to the stoichiometry between ATP production and electron transprt (ATP: 2e⊖). The system studied contained DCMU to inhibit electron flow from photosystem II, ascorbate and DPIP to supply electrons to photosystem I, and methylviologen as electron acceptor. The following results were obtained:

1. Basal electron transport is stimulated by the addition of the phosphorylating system, indicating that phosphorylation is really coupled to non-cyclic electron flow. The ratio ATP: 2e⊖ is 1, when the increase of electron flow obtained by the addition of ADP and phosphate is correlated to phosphorylation. This ratio is constant upon varying several parameters including DPIP concentration and light intensity.

2. In the absence of methylviologen a DPIP catalyzed cyclic phosphorylation takes place (cf. I. c.7, 11, 12). Phosphorylation is not increased by the addition of methylviologen, indicating that both, the cyclic DPIP mediated and the non-cyclic system are coupled to the same phosphorylation site and limited by the same reaction step.

3. In the absence of oxygen a methylviologen supported cyclic phosphorylation occurs. Comparing optimum rates, phosphorylation under these conditions is about twice as high as in the noncyclic system. Therefore we conclude that two phosphorylation sites are involved in methylviologen catalyzed cyclic electron transport. This system is sensitive against trypsin treatment of the chloroplasts, whereas the linear system is not.

4. The two cyclic systems as well as the non-cyclic system are coupled to reversible proton uptake. Furthermore the linear system exhibits an irreversible uptake of hydrogen ions, which is stoichiometric to electron flow. From the reversible and the irreversible components of the pH changes the ratio of the proton pump to electron transprt can be calculated. Under steady state conditions the ration H⨁ : e⊖ approaches 1.
Zur Elektronen-Strahlenchemie des Radikalfängers Diphenylpikrylhydrazyl in Methyljodid (I) / Electron-radiation Chemistry of the Radical Scavenger 1,1-Diphenyl-2-picrylhydrazyl in Methyl Iodide
Authors: Kalus Werner H.
Published: February 2015

The radical scavenger 1,1-diphenyl-2-picrylhydrazyl (DPPH) in methyl iodide solution was exposed to electron-rays in the absence of air, and the products were separated by thin-layer chromatography. The substances were characterised and identified as 1,1-diphenyl-2-picrylhydrazine (1), p-nitro-diphenylamine (2), 2,6-dinitro-diphenylamine (3), 1-phenyl-1-(p-nitrophenyl)-2-picrylhydrazine (4), and 2,4,6-trinitro-aniline (5). In addition some unidentified products are formed. The mass- and ir-spectrometric analysis of the low molecular weight products indicates that they are produced by the splitting of the N — N-bond in the DPPH molecule. From the material balance and the chemical compositions of the reaction products, it is presumed that the early stage of the decomposition of DPPH induced by electron-rays is a nitration of DPPH. A mechanism is formulated to explain the formation of the compounds.
Zur Chemie der Ketene / Chemistry of Ketenes
Authors: Wittmann Helga , Illi V. , Rathmayr H. , Sterk H. , Ziegler E.
Published: February 2015

Phenylmalonylchloride reacts with sodium acetate in boiling benzene if possible via a dimeric phenylketenecarboxylic acid to give 4-acetoxy-3,6,7-triphenyl-3,6-cycloheptadiene-1,2,5-trion. The structure of this compound is deduced by mass spectrometry. Analogous compounds are obtained with the sodium salts of other carboxylic acids. A reaction mechanism is proposed.
The Influence of the Aromatic Amino Acid Side-Chains on the Sign of the Soret Cotton Effect in Chironomus Hemoglobin (CTT III)
Authors: Fleischhauer Jörg , Wollmer Axel
Published: February 2015

The origin of the positive Soret Cotton effect of myoglobin was calculated by Hsu and WOODY on the basis of a mechanism taking into account the coupling of the Soret and aromatic side-chain π—π* transitions. HUBER and coworkers have worked out the atomic coordinates of a monomeric insect hemoglobin which exhibits a negative Soret Cotton effect.

It seemed of some importance to examine the capability of this mechanism to explain the observed inversion of sign. The calculations resulted indeed in a negative total rotational strength (—0,2 DBM), the main contributions arising from phenylalanine residues.
Metallkomplexe des N-Hydroxyharnstoffs / Metal Complexes of N-Hydroxy Urea
Authors: Berger Rainer , Fritz Heinz P.
Published: February 2015

The preparation of salts or complexes of N-hydroxy urea with Na+, Li+, Mg2+, VO2+, Mn2+, Fe3+, Co2+, Ni2+, Cu2+, Zn2+ und Pt2+ is reported. Their i.r.-spectra and the n.m.r.-spectra of the ligand and its alkali salts as well as of the methylated and deuterated derivative are discussed. Finally lhe complex stability constants of Mn2+, Co2+, Ni2+, Cu2+ and Zn2+ compounds are measured and discussed.
Die Komplexbildung zwischen Molybdationen und Perjodsäure, II / The Formation of Complexes between Molybdate Ions and Periodic Acid, II
Authors: Wiese Günther
Published: February 2015

By UV-spectrophotometric titrations and a mathematical analysis of the titration results the complex formation between polymolybdate and periodic acid was investigated. In the studied concentration range the following two heteropolyanions were identified: [JMo6O24] 5– and [J2Mo2O15]4–

As reported by H. COPAUX 1 in 1913 and later by G. JANDER et al. 2 the salts of the heteropolyacids are characterised by strong light absorption in the UV in contrast to the acids from which these salts have been prepared. Therefore the UV-spectroscopy is suitable for studying the formation of heterocomplex compounds.
59Co-NMR-spektroskopische Untersuchungen an [Co(NO)2X(PZ3)]-Komplexen / 59Co NMR Spectroscopic Investigations of [Co (NO) 2X (PZ3)] Complexes
Authors: Rehder Dieter , Schmidt Jörn
Published: February 2015

59Co-nmr-spectroscopic investigations of solutions of the complexes [Co (NO)2X(PZ3)]* in CH2Cl lead to relations between the chemical shift τo and bonding parameters of the Co-X-bond and the Co-PZ3-bond, respectively. With decreasing chemical shift, covalency of the Co-X-bond is increasing in the order Cl<Br<J. Regarding the PZ3 ligands, τCo is a measure of the π-acceptor ability of PZ3, which increases in the order PPh3 ∼ PPh2Z ∼ PPhCl2 < alkylphosphine ∼ phenylalkylphosphine ∼ phosphines containing NR2-groups < phosphines containing OR-groups. The different π-accetor abilities are explained by varying Z-P-interaction.
Ein makroporöses Polyacrylamid für immunologische Diffusionstechniken / Macroporous Polyacrylamide, its Use for Immunological Diffusion Techniques
Authors: Determann Helmut , Walch Axel
Published: February 2015

Gel layers of crosslinked polyacrylamide with different porosities were synthesized and their properties compared. At high concentrations of bifunctional monomers macroporous gels were formed, one of which (total monomer concentration 14%, methylene-bis-acrylamide 40%) permitted even high molecular weight proteins (e. g. γ-globulins) to diffuse more readily than in 2 per cent agar or agarose gels. Different immunological techniques were modified for application with this polymer. It offers advantages especially with respect to porosity, storability and sample application for quantitative diffusion techniques.
Chelation Reactions of Adenine
Authors: Nayan Ram , Dey Arun K.
Published: February 2015

Chelation reactions of the antimitotic drug, 6-amino-purine (adenine; abbr. ADN) with the metal ions: Be(II), Al(III), Cr(III), Mn(II), Fe(III), Co(II), Ni(II), Cu(II), Pb(II), and UO2(II) have been investigated in aqueous solution at 30° using Bjerrum-Calvin pH titration technique. The formation constants have been determined at various ionic concentrations, and have been extrapolated to zero ionic strength to get the thermodynamic values of the constants.
Studies on Dehydrogenase Levels in Uromastix Hardwickii during Active and Hibernating Periods
Authors: Hasnain S. N. , Ramwani J.
Published: February 2015

LDH, SDH and G-6-PDH activities have been determined in Uromastix hardwickii which hibernates during winter. Protein concentration was found to be significantly higher in liver than in kidney during active and hibernating periods. Protein concentration was decreased significantly in both the tissues during hibernation.

LDH activity was significantly higher in the hibernating period in both liver and kidney. SDH activity was significantly reduced in liver during hibernation but increased significantly in kidney. There was a significant decrease in G-6-PDH activity in liver but only a slight decrease in kidney during hibernation.
The Photoinactivation of Tobacco Transketolase in the Presence of Flavin Mononucleotide
Authors: Codd Geoffrey A.
Published: February 2015

Transketolase from the leaves of Nicotiana tabacum var. John William′s Broadleaf is inhibited by exposure to low intensity blue light in the presence of low concentrations of FMN, which functions as a sensitizer. The degree of photoinactivation is reduced in the presence of quenchers of triplet FMN. Photoinactivation does not occur in the absence of oxygen and is also lessened in the presence of quenchers of singlet oxygen. The mechanism of photooxidation is inferred to proceed by way of triplet FMN and a major route of inactivation of the enzyme may continue via singlet oxygen.
Darstellung und Kristallstruktur des K2Sb4S7 / Preparation and Crystal Structure of K2Sb4S7
Authors: Graf H. A. , Schäfer H.
Published: February 2015

In the K2S/Sb2S3-System the compound K2Sb4S7 has been prepared and its structure determined. In this structure there are two differently coordinated Sb-atoms: the SbI-atoms in the vertices of flat SbS3-pyramides have the CN 3 to sulfur, the SbII-atoms are ψ-trigonal-bipyramidal coordinated with one free position in the equatorial plane. These polyhedra are connected to each other by common corners and edges to a three-dimensional net, which has channels parallel the b-axis, in which the K+-ions are located.
Über das Verhalten von Dithiophosphinatokomplexen des Rheniums gegenüber Ammoniak / About the Behavior of Dithiophosphinato Complexes of Rhenium towards Ammonia
Authors: Lindner E. , Berke H.
Published: February 2015

According to eq. (1) the hitherto unknown (C2H5)2PSS--bridged [ (C2H5)2PSSRe (CO) 3NH3]2 (1) is obtained by reaction of [(C2H5)2PSSRe(CO)2]2 with liquid ammonia between -70° and -30°. The complex can be transformed into the monomeric (C2H5)2PSSRe (CO) 3NH3 according to eq. (2) at room temperature in THF. The 1H NMR and IR spectra of the newly prepared compounds are discussed.
Linosid A und B, zwei neue Flavon-C-glykoside aus Linum maritimum L. / Linoside A and B, Two New Flavone-C-glycosides from Linum maritimum L.
Authors: Wagner H. , Budweg W. , Iyengar M. A. , Volk O. , Sinn M.
Published: February 2015

Linoside from Linum maritimum L. to which the structure 3′,4′-Dimethyl-luteolin-7-0-rhamnoside was assigned by VOLK and SINN turned out not to be identical with the synthesized glycoside. On reinvestigation Linoside could be separated into two components (Linoside A and B) and structurally elucidated as the new flavone-C-glycosides 5-hydroxy-7,3′,4′-trimethoxy-flavone-6-C- [6-or 2-O α-L- (O-acetyl-rhamno) -β-ᴅ-glucopyranoside and its desacetylderivative respectively.
Increased Oxygen Consumption of Ehrlich Ascites Tumor Cells Following Serial Cultivation in Media with Increased (Hypertonic) NaCl Content
Authors: Kürschner E. , Schachtschabel D. O.
Published: February 2015

Ehrlich ascites tumor cells adapted to serial cultivation in vitro in media with increased NaCl content (“high-salt”-tolerant cells) exhibit — in comparison with cells cultivated either in isotonic media or intraperitoneally in mice (in vivo) — an increased rate of cellular oxygen consumption. It is suggested that this increased respiratory rate of “high-salt”-tolerant cells reflects enhanced energy requirements associated with processes of active ion transport; and that the elevated environmental NaCl concentration may have “induced” a “step up” of the respiratory metabolism of these tumor cells.
Elektronische Struktur und karzinogene Aktivität von 3.4-Benzpyren und 1.2-Benzpyren / Electronic Structure and Carcinogenic Activity of 3,4-Benzpyrene and 1,2-Benzpyrene
Authors: Popp Fritz A.
Published: February 2015

The differences in the properties of electronic structure between 3,4-Benzpyrene and 1,2-Beuzpyrene are used to construct a possible model of the mechanism of chemical carcinogenesis. This model proposes an alternative hypothesis to Masons theory and describes the primary step *n carcinogenesis as a resonance-phenomenon between the carcinogenic hydrocarbon and the bioreceptor which is likely to be a base of DNA or RNA.
Notizen:Neue Verbindungen im ThCr2Si2-Typ / New Compounds in the ThCr2Si2-Type
Authors: May N. , Schäfer H.
Published: February 2015

Structural chemistry of intermetallic AB2X2-Compounds
Ein Beitrag über SrCeAlO4 und SrNdAlO4 / About SrCeAlO4 and SrNdAlO4
Authors: Pausch H. , Müller-Buschbaum Hk.
Published: February 2015

X-ray diffraction datas

Single crystals of SrCeAlO4 and SrNdAlO4 were examined by X-ray diffraction. A comparison of the distances of the statistically occupied metal positions of the K2NiF4-type with Sr2CuO3 stresses the structure relation between the K2NiF4-type and Sr2CuO3.
A Labile CO2-Fixing Enzyme Complex in Spinach Chloroplasts
Authors: Müller Bruno
Published: February 2015

Activity and activation of ribulose 5-phosphate kinase, ribulose diphosphate carboxylase, phosphoglycerate kinase, and the NADP- and NAD-dependent glyceraldehyde phosphate dehydrogenases from isolated diloroplasts were traced in the course of differential ultracentrifugation. Activation of some of these enzymes was carried out by incubation with NADPH2 or ATP. Activity of ribulose diphosphate carboxylase could be increased 2,4-fold by incubation with NADPH2 while phosphoglycerate kinase could not be activated.

The degree of activation of the NADP-specific glyceraldehyde phosphate dehydrogenase and ribulose phosphate kinase was correlated with the velocity of sedimentation. Enzymes, which could be activated manifold, sedimented more quickly. Two fractions could be obtained after ultracentri fugation: the sedimented fraction could be highly activated while the fraction in the supernatant could not.

It was shown by gel chromatography with Sephadex for the NADP-specific glyceraldehyde phosphate dehydrogenase and ribulose phosphate kinase that the enzyme fractions which could be greatly activated had molecular weights of at least 400 000. In contrast, the enzyme fraction which could not be activated had a molecular weight of 50 000 for the ribulose phosphate kinase and of 240 000 for the glyceraldehyde phosphate dehydrogenases.

Results are discussed in the way that a reversible dissociation of a labile enzyme complex takes place between ribulose phosphate kinase, glyceraldehyde phosphate dehydrogenases, and ribulose diphosphate carboxylase. Enzyme activity changes with the state of aggregation. The dissociated enzymes have higher activity than the complexed ones. Dissociation can be performed by ATP and NADPH2, which are assumed to be the physiological regulators, and by unphysiological means as dilution and high salt concentrations.
The Distribution of Photosynthetic Reactions in the Chloroplast Lamellar System
Authors: Sane P. V. , Hauska G. A.
Published: February 2015

Plastocyanin is released from chloroplasts by sonication, by passing through the French-press, by extraction with detergents, by treatment with organic solvents and by freezing and thawing. No plastocyanin is liberated during osmotic shock of either class I or class II chloroplasts, or by extraction of class II chloroplasts with dilute solutions of EDTA.

Under special conditions it is possible to separate grana and stroma lamellae, which retain plastocyanin. The distribution of plastocyanin between these membrane fractions parallels the distribution of photosystem I.

The different reactivity of plastocyanin with various chloroplast membrane preparations is not always correlated to plastocyanin content. Other parameters, like pH, seem to influence the interaction of plastocyanin with the surface of the chloroplast membrane.
The Distribution of Photosynthetic Reactions in the Chloroplast Lamellar System
Authors: Hauska G. A. , Sane P. V.
Published: February 2015

Chloroplast fragmentation, ATPase, Proton pump, Cyclic Phosphorylation, NH4Cl-uncoupling

Cyclic phosphorylation and latent ATPase follow the distribution of photosystem I in the chloroplast membrane. Both activities are found higher in stroma lamellae than in grana. The extent of proton uptake is found to be higher in the grana. Since this uptake depends on internal volume and buffer capacity besides proton pump activity, the distribution of the proton pump proper remains to be elucidated.

Any fragmentation of the large inner compartment of the chlorolast lamellar system into smaller vesicles results in decreased sensitivity of cyclic phosphorylation to uncoupling by ammonium chloride. Consequently both, isolated grana and stroma lamellae, show decreased uncoupling by ammonium chloride. The effect can be explained by the action of a membrane potential in photophosphorylation which builds up during illumination and might be more stable in a system with the larger number of individual compartments just for statistical reasons. No assumption on changes in specific ion permeabilities during fragmentation of chloroplasts are needed.
The Metabolic Fate of Hydroxybenzoic Acids in Plants
Authors: Cooper-Driver Gillian , Corner-Zamodits J. Janet , Swain T.
Published: February 2015

When fed to higher plants, hydroxybenzoic acids form O-glucosides unless they contain an ortho-hydroxyl group when glucose esters are formed. The properties and methods of identification of several of these derivatives are outlined.
Phototrophic Growth of Rhodopseudomonas gelatinosa on Citrate; Accumulation and Subsequent Utilization of Cleavage Products
Authors: Schaab Christine , Giffhorn Friedrich , Schoberth Siegfried , Pfennig Norbert , Gottschalk Gerhard
Published: February 2015

Rhodopseudomonas gelatinosa grows on citrate anaerobically in the light. Under aerobic conditions citrate cannot be utilized. Citrate is rapidly fermented by Rps. gelatinosa in the dark, and this fermentation is associated with limited growth (one generation). Anaerobically in the light citrate is decomposed much faster than its catabolic products can be used for the synthesis of cellular material. Therefore, acetate and malate are accumulated in the medium. The acetate concentration in the medium after complete consumption of citrate is higher than the original citrate concentration. Acetate is formed by the citrate lyase reaction and by partial degradation of oxaloacetate. After exhaustion of citrate, growth of Rps. gelatinosa continues at the expence of acetate.
Acid and Alkaline Phosphatase Levels in Various Tissues of a Lizard during Activity and Hibernation
Authors: Aziz Shakila , Hasnain S. N. , Zain-Ul-Abedin M.
Published: February 2015

1. Acid phosphatase (AcPase) and alkaline phosphatase (AlPase) activities and specific activities were determined in six different tissues of Uromastix during active and hibernating periods.

2. The protein concentration was significantly reduced in all the tissues during hibernation.

3. pH optima of acid and alkaline Pases were found to be 4.2 and 9.2 respectively.

4. AcPase activity was increased in all the tissues except liver and small intestine during hibernation.

5. AlPase activity was increased in all the tissues except small intestine during hibernation.

6. Specific activities of both the enzymes were increased during hibernation.
Anreicherung und Charakterisierung einer „Transhydrogenase-Aktivität“ und der 17 β-Hydroxysteroid-Oxidoreduktase aus der Cytoplasma-Fraktion der Leber von weiblichen Ratten / The Enrichment and Characterisation of Cytoplasmatic “Transhydrogenase-activity” and 17 β-hydroxysteroid-oxidoreductase from Rat Liver
Authors: Pollow Kunhard , Pollow Barbara
Published: February 2015

The cytoplasmatic fraction of rat liver contains both 17 β-hydroxysteroid-oxidoreductase and a “transhydrogenase-activity”, which catalyses the transfer of hydrogen from the 17 β-position of estradiol-17 β to the 17-position of 4-androstene-3,17-dione. The 17 β-hydroxysteroid-oxidoreductase was purified 718-fold and the “transhydrogenase-activity” 264-fold by ammonium sulphate precipitation, gel chromatography with Sephadex G-200, column chromatography on DEAE-Sephadex and isoelectric focusing. The two enzymic activities could not be separated. The characteristics of the two enzymatic activities give some evidence that the “transhydrogenase-activity” is identical with the already known 17 β-hydroxysteroid-oxidoreductase.

Isoelectric focusing of the chromatographycally enriched 17 β-enzyme gave an isoelectric point at 5,2. The 17 β-enzyme has a molecular weight of 62 — 65 000 as determined by mobility on Sephadex G-200 superfine.

The kinetic constants for both the 17 β-enzyme and the “transhydrogenase-activity” were determined.
In vivo Methylation of DNA in Different Organs of Rat at Various Ages
Authors: Lutz Dieter , Löwel Marianne , Kröger Hans , Kubsch Diethard , Uecker Wilhelm
Published: February 2015

We investigated in vivo labelling of DNA in single organs of female Wistar rats after application of 3H-methionine. In 40 g and 120 g rats the tritium incorporation into DNA was 10 times higher in spleen than in liver, kidney and heart. DNA methylation in newborn rats (6 — 8 g) was more pronounced in each of these organs. We demonstrated a varying degree of tritium incorporation into the different bases of DNA depending on the organs. We claim that only the values for 5-methylcytosine should be used as sole criteria of DNA methylation. Our results indi cate that DNA methylation in vivo is enhanced in those organs, where a more intensive DNA synthesis occurs.
Photochemically Induced Adduct Formation with Flavin in Pyridine
Authors: De Κοk A. , Peters C. F. A. H.
Published: February 2015

3-methyllumiflavin, irradiated in the first flavin band, forms a N-5 adduct in pyridine solutions. The possible nature of this adduct is discussed, together with the effect of water on the course of the photoreduction reaction.
Formation and Possible Structure of Covalent Hydrates of Alloxazines
Authors: Koziol Jacek , Metzler David E.
Published: February 2015

A slow and reversible hydration of N (1) -unsubstituted alloxazines in aqueous alkaline solutions has been studied. Reaction products stable (kinetically) in neutral and acidic solutions were isolated and investigated by IR, NMR, UV and mass spectroscopy. The possible mechanism of the reaction and the structure of the isolated products is discussed.
Photo-addition Reactions in the Benzenoid Subnucleus of Flavoquinones
Authors: Schöllnhammer G. , Hemmerich P.
Published: February 2015

By photochemical attack on flavin cations, compounds substituted in the benzenoid subnucleus have been prepared. Water and alcohols can be added in this way and under certain conditions the alcoholic groups of the flavin side chain are involved. Structures and properties of photoproducts are described.
Covalent Intermediates in Flavin-sensitized Photodehydrogenation and Photodecarboxylation
Authors: Knappe W.-R. , Hemmerich P.
Published: February 2015

The photoreactions of the flavin triplet with unsaturated hydrocarbons, aldehydes, sulphur compounds, and carbonic acids are reported. These reactions proceed by attack at the allylic C-H-, the RCO-H-, or the α-C-H-bond, respectively; in the case of carbonic acids decarboxylation occurs. In all the reported reactions covalent adducts are formed, whose structure and mode of decay is characterized.
Model Studies on Flavin-Dependent Carbonyl-Activation: Reduction of Carbonyl Compounds by Flavohydroquinone
Authors: Blankenhorn G. , Ghisla S. , Hemmerich P.
Published: February 2015

The reduction of aldehydes by flavohydroquinone to yield the corresponding alcohols and flavoquinone is reported and discussed in view of its relevance to the mechanism of flavin-dependent dehydrogenation and carbonyl activation. With formaldehyde and flavohydroquinone formation of a covalent 5- (HO - CH2) Flred⁻ intermediate species is observed. In a reverse reaction 5-methylflavoquinonium cation undergoes an internal redox reaction to yield flavohydroquinone and formaldehyde.
Intermediates in the Neutral Photolysis of Riboflavin
Authors: Schuman Jorns Marilyn , Hemmerich Peter
Published: February 2015

The formation of a species with an absorption maximum around 410 nm, observed during the neutral photolysis of 10-(2'-hydroxyalkyl) flavins by earlier authors, is shown to depend on the presence of divalent anions. The structure of this new type of compounds is presented and a possible mechanism for the reaction is discussed.
Circular Dichroism, Self Interaction and Side Chain Conformation of Riboflavin and Riboflavin Analogues
Authors: Scola-Nagelschneider G. , Hemmerich P.
Published: February 2015

The CD-spectra of riboflavin and riboflavin analogues in aqueous solutions differ very little depending on pH and ionic strength, but are extremely sensitive upon solvent changes. The two bands in the region of 300 —500 nm seen in aqueous solutions are split into seven bands in less polar solvents, which can be assigned to seven vibronic transitions. The spectra may be interpreted by “through space” and “through chain” interactions of the sidechain centers of chirality with the flavin chromophore, which influence the two first π —π* transitions in different manner.
Proton Magnetic Resonance Studies of Flavoquinone-Metal Complexes
Authors: Lauterwein J. , Hemmerich P. , Lhoste J.-M.
Published: February 2015

A detailed magnetic resonance investigation of the metal ion interaction with flavoquinones has been carried out with the purpose of obtaining the stoichiometry, stability and (sub) molecular structure of the complexes. The isotropic shifts of the paramagnetic chelates are analysed in terms of contact and pseudocontact contribution. It is shown that the flavoquinone-metal binding is mainly of σ-type regardless of the nature of the ion.
4a,5-Cycloaddition Reactions of Acetylenic Compounds at the Flavoquinone Nucleus as Mechanisms of Flavoprotein Inhibitions
Authors: Zeller E. A. , Gärtner B. , Hemmerich P.
Published: February 2015

4a,5-Cycloaddition at the flavoquinone, Mechanism of flavoprotein inhibitions

Photochemically, covalent cycloaddition products of flavoquinone and acetylenic enzyme inhibitors have been prepared and elucidated, which appear analogous to flavoprotein-inhibitor complexes (monoamine and lactate oxidase). The additions occur with inhibitors of general type HC≡C-CH< at the C (4a) = N (5) azomethine grouping of oxidized flavin. The spectral properties of adducts and their chemical reactivity is described.
Comparison of Stopped Flow and Steady State Kinetics in the Reaction of D-Amino-Acid Oxidase with β-Chloroalanine
Authors: Voet Judith G. , Porter David J. T. , Bright Harold J.
Published: February 2015

We describe anaerobic stopped-flow monitored interactions of D-B-chloroalanine with D-amino acid oxidase and show that the kinetics of absorbance changes at 550 nm due to enzyme-bound intermediates can not be correlated with steady state turnover behavior unless it is assumed that only a small fraction of the enzyme directly participates in the α-β elimination process.
Comparative Kinetics between Matrix-bound Lipoamide Dehydrogenase and the Free Enzyme
Authors: Visser Jaap , Havekes Louis , Veeger C.
Published: February 2015

Lipoamide dehydrogenase (EC 1.6.4.3) has been succesfully linked to a CNBr-activated polysaccharide matrix, Sepharose-4B, under different reaction conditions. The enzyme is probably bound more homogeneously at lower pH values (pH 7.5) than at pH 8.5. Such immobilized preparations yield V values 8-30% of the value of the V of the free enzyme (18,600 mole/min/mole of flavin). A low level of CNBr-activation in combination with substrate protection and a pH of 7.5 during the coupling reaction leads to the most active preparations. The Km values for both substrates increase considerably.

The overall kinetic pattern of the matrix-bound enzyme preparations is not different from that of the free enzyme. Both activation by high concentration of lip (SH)2NH2 at low NAD+ levels and a stimulation of the V by increased phosphate concentration in the assay buffer is observed with free and some immobilized enzymes.
Oxygen Reaction of 4-hydroxybenzoate Monooxygenase
Authors: Ullrich Volker , Bernhardt Frithjof-Hans , Diehl Horst , Erdin Nazmiye , Ruf Hans-Heinrich
Published: February 2015

4-hydroxybenzoate hydroxylase from Ps. putida has been studied with regard to the oxygen interaction with the reduced flavin. By rapid scanning spectrophotometry and EPR-measurements of rapidly frozen mixtures no intermediate could be established either in the presence of 4-hydroxybenzoate or the dead-end inhibitor 6-hydroxynicotinic acid.
Covalently Bound Flavin in D-6-Hydroxynicotine Oxidase from Arthrobacter oxidans
Authors: Brühmüller M. , Möhler H. , Decker K.
Published: February 2015

D-6-hydroxynicotine oxidase contains 1 mole of FAD covalently bound to one mole of enzyme. To identify the covalent linkage between FAD and protein, an amino acid derivative of riboflavin (HNO-flavin) was isolated and purified. It was obtained from flavin peptides by hydrolysis with 6 N HCl at 95°C or with aminopeptidase M. The riboflavin derivative had the spectral characteristics of 8α-substituted flavins. It showed a pH-dependence of fluorescence with a pK of 4.65 and 86% quenching at pH 7. In thin layer chromatography it was identical with 8α-(N-3-histidyl)-riboflavin. Hydrolysis of HNO-flavin in 6 N HCl at 125°C liberated 1 mole of histidine per mole of flavin as shown by amino acid analysis. Since FAD is the coenzyme of D-6-hydroxynicotine oxidase, these results are taken as evidence that this enzyme contains 8a- (N-3-histidyl) -flavin-adenine-dinucleotide in the active center.
Sequence around the Active Center Cystine of Lipoamide Dehydrogenase from Pig Heart, Comparison with the E. coli Enzyme
Authors: Williams C. H. , Arscott L. D.
Published: February 2015

Catalysis by lipoamide dehydrogenase involves the concerted action of the flavin and a cystine residue. Peptides containing this cystine residue have been previously isolated from E. coli and now from pig heart. The sequences of amino acid residues reveal a high degree of homology indicating a strict conservation of the region around the active site cystine during the long evolutionary period between these two species. The peptide sequences suggest a likely conformation of the polypeptide chain in the region of the flavin as well as the forces involved in substrate and flavin binding.
Butyryl Coenzyme A Dehydrogenase: Studies on the Specificity of the Formation of Acyl Coenzyme A Complexes with Long-Wavelength Absorption
Authors: Engel P. C.
Published: February 2015

Further studies of butyryl CoA dehydrogenase show that the enzyme forms tight complexes with long-wavelength absorption bands upon addition of α, β-unsaturated alicyclic carboxylic acyl CoA compounds. As in the straight chain series, the size of the acyl moiety is critical. The thiol portion by contrast determines neither whether a long-wavelength band is formed nor the wavelength of maximum absorption if such a band is present. It does however markedly affect the dissociation constant. Unusual features of the acid stability of the acyl CoA found on the native green form of the enzyme are also reported.
The Reduction of Flavodoxin from Azotobacter vinelandii by Pyruvate
Authors: Bothe H. , Falkenberg B.
Published: February 2015

Pyruvate is shown to be a substrate for the reduction of flavodoxin from Azotobacter vinelandii, using the phosphoroclastic enzyme system from Clostridium pasteurianum. In this reaction, the reduction of this flavoprotein proceeds beyond the semiquinone state partly to the hydroquinone form. Pyruvate is possibly the substrate for the reduction of flavodoxin in the intact organisms.
Amino Acid Sequences of Clostridium pasteurianum Flavodoxin
Authors: Fox J. L. , Smith S. S. , Brown J. R.
Published: February 2015

The amino acid sequences of 10 tryptic peptides from C. pasteurianum flavodoxin are determined and ordered. The sequence of two thirds of the protein is presented. New electrophoretic techniques for sequence determination are also presented.
Notizen: Circadian Rhythm of Oxygen Consumption in Rat Liver Suspension Culture: Changes of Pattern
Authors: Langner R. , Rensing L.
Published: February 2015

Circadian rhythm, oxygen consumption, rat liver, suspension culture, bimodal pattern
Zusammenhang zwischen Kernquadrupol-Kopplungskonstanten und π-Bindungsordnung ausgewählter anorganischer 2Π- und 3 Σ-Radikale / Correlation between the Nuclear Quadrupole Coupling Constants and π-bond Order of Some Inorganic 2Π and 3Σ Radicals
Authors: Machmer Paul
Published: February 2015

The nuclear quadrupole coupling constants of the 4 radicals 14NO (2Π3/2), 14NCO (2Π3/2, 14NS (2Π3/2), 33SO (3Σ-) and the 17 diamagnetic molecules 14N2O, 14N2H, 14NSF3, 14NSF, 33SCNH, 33SCO, 33SC, 33SSi, 73GeSe, 14NP, 14N≡C-H, 14N≡C-CH3, 14N≡C-CF3, 14N≡C-SiH3, 14N≡C-GeH3, 14N≡C-C-C≡C-H, 14N≡C-C≡C-CH3 have been analyzed in terms of the π-bond order. Satisfactory results are obtained when the π-bond order is expanded in powers of the ratio

The validity range of this function is defined.
Untersuchungen an biochemisch wirksamen Ligandensystemen, V
Authors: Barz P. , Fritz H. P.
Published: February 2015

1,2-Dimethylhydrazine co-ordinates to numerous metal cations. The structures of the complexes of Cr, Mn, Co, Ni, Cu, Zn, Cd, Hg and Pt are discussed and the complexing abilities of the 1,2-dimethylhydrazine molecule are determined on the basis of the ligand field spectra of the nickel and the chromium derivative.

The results of polarography, cyclic voltammetry and photoelectron spectroscopy yield evidence on the redox properties of the neutral molecule. By means of EPR spectroscopy the nature of the radical products obtained by irradiation of 1,2-dimethylhydrazine, especially of the radical cation, is determined.
Dipeptidesterkomplexe von Platin(II) durch Peptidsynthese an N-koordinierten α-Aminosäuren / Dipeptide Ester Complexes of Platinum (II) from Reaction of N-coordinated α-Amino Acids with Amino Acid Esters
Authors: Purucker Bernhard , Beck Wolfgang
Published: February 2015

Complexes of the type trans-X2Pt (NH2CHRCOOH)2 (X = Cl, Br, J; R = H, CH3, CH(CH3)2, CH2OH) react with amino acid esters (GlyOCH3, GlyOC2H5) and N,N′-dicyclohexylcarbodiimide as coupling agent to form the corresponding dipeptide ester derivatives trans-X2Pt (NH2CHRC (O) NHCH2CO2R′) 2. In these reactions the metal ion acts as N-terminal protecting group. The infrared spectra of the new compounds are reported.
Über die Berechnung der 1H-NMR-Spektren linearer Di-aza-acene / On the Calculation of 1H-NMR-Spectra of Linear Di-aza-acenes
Authors: Ege G. , Vogler H.
Published: February 2015

It is shown, that the calculation of chemical proton shifts and coupling constants of linear di-aza-acenes within the framework of HMO-theory gives values close to experimental ones.
Salzbildung der Diazoaminobenzole (Triazene) im Zuge der Elektrolyse in aprotischem Lösungsmittel / Salt Formation during Electrolysis of Diazoaminobenzenes (Triazenes) in Aprotic Solvent
Authors: Holleck Ludwig , Kazemifard Gholamali
Published: February 2015

In contrast to aqueous and methanolic solutions the polarographic reduction of diazoaminobenzenes (DAAB) in the aprotic solvent dimethylformamid occurs in two waves with the combined hight corresponding to a four electron reduction.

The first wave results from the four electron reduction of the fraction (1/5) of the DAAB molecules which obtain the necessary protons from the remaining (4/5) DAAB molecules. The resulting DAAB anions are only reduced at the considerably more negative potentials of the second wave. Then the reduction occurs also in a four electron step and leads to the cleavage of the molecule. Potentiostatic electrolysis at the limiting current region of the first polarographic wave results in coloured solutions. The colour depends on the nature of the substituent. Salt formation was monitored spectrophotometrically and inferences pertaining to structure are drawn. The experimental results show that mercury compounds which might possibly be formed as intermediary species react immediately with the cations of the supporting electrolyte to form the corresponding DAAB salts.
Synthesis of Biologically Active Triazenes from Isolable Diazonium Salts
Authors: Kolar G. F.
Published: February 2015

Alkaryl triazenes were synthesized in two steps from the isolated intermediary diazonium tetrafluoroborates and hexafluorophosphates by coupling the arenediazonium cations with dimethylamine in an aqueous solution but without the use of mineral base. The method enables the preparation of triazenes which are not readily accessible by conventional procedures; it also leads to higher yields and purer products in the preparation of known compounds.
Nachweis der Proteinbindung von Ecdyson bei der Schmeißfliege MEIGEN Calliphora erythrocephala / On the Protein Binding of Ecdysone in the Blowfly, Calliphora erythrocephala
Authors: Thamer Günther , Karlson Peter
Published: February 2015

Binding of ecdysone to a protein fraction of the hemolymph of mature Calliphora larvae has been demonstrated by use of the gelfiltration technique. Binding occurs in vivo after injection of labelled ecdysone as well as in vitro on incubation of either hemolymph or a 100 000 g-supernatant of a homogenate with ecdysone. The protein-ecdysone complex can be fractionated by DEAE- or CM-cellulose chromatography; however, the protein seems to be denatured on prolonged dialysis, so that a measurement of the equilibrium constant was not possible.
Schnellmarkierte RNS in heterotroph kultivierten Geweben von Nicotiana tabacum / Rapidly Labelled RNA in Heterotrophically Cultured Tissues of Nicotiana tabacum
Authors: Beisenherz Wolfgang
Published: February 2015

The RNA metabolism in tissue cultures of Nicotiana tabacum has been studied by incorporation of radioactive phosphate. The RNA was extracted by phenol-kresol-hydroxychinon and fractionated by MAK columns. A rapidly labelled RNA fraction was eluted from the MAK column after the rRNA components. Its base ratio differed from the latter in that the AMP content (28,6%) was higher than the GMP content (26,0%). Sedimentation analysis on sucrose gradients showed a sedimentation coefficient of 37 -38s. The life time of the 37-38s RNA fraction in chase experiments was 3,5-4 hours. Differential centrifugation of tissue homogenates revealed that the labelled 37-38s RNA was associated with particles sedimented by low speed centrifugation. No 37-38s RNA could be detected in the ribosomal fraction and the supernatant. During chase experiments label appeared in the rRNA components. It could be excluded by thin layer chromatographic separation of 32P labelled compounds that this label originated from 32P-o-phosphate or labelled organic phosphates except of the rapidly labelled 37-38s RNA. From this it was concluded that the 37-38s RNA is a precursor of the rRNA.
Untersuchungen zur Lokalisation von Flavonoiden in Plastiden, I / Experiments on the Localisation of Flavonoids in Plastids, I
Authors: Weissenböck Gottfried , Fleing Ingrid , Ruppel Hans Georg
Published: February 2015

Etioplasts aqueously isolated from leaves of etiolated plants of two varieties of Avena sativa contain all the flavonoid compounds of the whole leaf: apigenin-7-methoxy (?)-8-C-rhamnosylglucosylgly (u) coside (or -8-C-glucosylrhamnosylgly (u) coside), apigenin-6-C-arabinosylglucoside, apigenin-8-C-glucosylglucoside and in variety 1 a derivative of kaempferol, in variety 2 the flavone-C-glycoside saponaretin. The distribution of these compounds however is different in etioplasts and leaves: in etioplasts of variety 1 the kaempferol-derivative, in those of variety 2 saponaretin is relatively enriched. Presence of flavonoids could also be demonstrated in isolated prolamellar bodies from etioplasts of Avena variety 2.
Cleavage of ATP by Mouse Uterine Chromatin after in vivo Administration of Oestradiol
Authors: Rainer Maurer H.
Published: February 2015

The capacity of mouse uterine chromatin, prepared according to TENG and HAMILTON, to degrade 8-14C-ATP to ADP, AMP and adenosine and to cleave γ-32P-ATP to inorganic phosphate and other still unknown phosphorylated byproducts has been demonstrated over a wide range of conditions of the template assay. The dependence of the reactions on the time course of incubation, on the chromatin quantity and on the temperature was studied. In vivo administration of oestradiol depresses the apparent ATPase activity of mouse uterine chromatin consistently by 10-35 per cent, depending on chromatin preparation, amount and incubation period. The data are compatible with the suggestion that mouse uterine chromatin may contain low quantities of ATPases which are firmly bound to the chromatin structure and which might interfere with the template assay under average conditions, depending on the chromatin preparation. The findings are discussed in view of the possible role of ATPases in uterine chromatin under oestradiol influence.
Über die stufenweise Oxidation von Graphit in nichtwäßrigen, neutralen Elektrolyten / On the Stage-Wise Oxidation of Graphite in Nonaqueous, Neutral Electrolytes
Authors: Besenhard Jürgen , Fritz Heinz P.
Published: February 2015

Electrolytic lamellar compounds of graphite with well-defined oxidation stages were indicated by characteristic changes in the potential of a graphite anode during galvanostatic oxidation in nonaqueous, aprotic electrolytes.

In analogy to the well-known graphite salts in acid media e. g. C24HSO4·2 H2SO4
1,2 a Cn-stage with n = 24 besides others with n>24 was obtained in solutions of LiClO4, NaBF4 or KPF6 in propylene carbonate; further oxidation of graphite does not cause significat changes in the potential of the electrode. Such defined stages of oxidation were observed at graphite anodes in various nonaqueous electrolytes.

According to the present results simple salt-like lamellar compounds of the general type CnX are proposed; contrary to graphite salts prepared in concentrated acids, intercalation of free electrolyte is not a matter of priciple.
Halogenierungs- und Oxidationsreaktionen an Metallchelatverbindungen / Halogenation- and Oxidation-reactions on Metal-chelate Compounds
Authors: Biedermann Hans G. , Schwarzhans Karl E. , Wiedemann Werner
Published: February 2015

Reactions of acetylacetonate-, salicylaldehydate- and methylsalicylate-metal compounds with oxygen, bromine and sulfurylchloride were investigated. It was found, that these reactions yield to a variety of products depending on the used central metal ion.
Zur Anwendung von Extinktionsdiagrammen des Stillbens in Perfluormethylcyclohexan./Kinetic Analysis of Photochemical Reactions Using Extinction Diagrams
Authors: Mauser Heinz , Niemann Hans-Joachim , Kretschmer Rainer
Published: February 2015

Extinction diagrams are applied for determining the number of partial reactions. In this paper a method is described for the calculation of the concentration of the reacting substances with the aid of extinction diagrams. The concentration values are more suitable for calculation of the rate constants, and in case of photochemical reactions the partial quantum yields, than the directly measured extinction values. The method of calculation is illustrated using the photochemical reaction of stilbene in a perfluorinated solvent as an example.
Zur Anwendimg vpm Extinktionsdiagrammen bei der kinetischen Analyse von Photoreaktionen / Kinetic Analysis of Photochemical Reactions Using Extinction Diagrams
Authors: Mauser Heinz , Starrock Volker , Niemann Hans-Joachim
Published: February 2015

The reaction of anthraquinone in alkaline methanol irradiated with 313 nm light is followed spectrophotometrically. The experimental results point to an irreversible consecutive reaction A → B → C. Since the concentration and extinction coefficient of the intermediate are unknown, the partial quantum yield cannot be calculated. A new method is described for calculation of the concentration of the unknown intermediate using the extinction diagram. It is suitable for consecutive reactions, if the rate constant of the first reaction-step is very great as compared with that of the second. Now the partial quantum yields of the two reaction-steps can be calculated.
Über das Assoziationsverhalten des Schlenkschen Kohlenwasserstoffs / About the Association of Schlenk’s Hydrocarbon
Authors: Schmidt Reinhard , Brauer Hans-Dieter
Published: February 2015

The association of Schlen k’s hydrocarbon was studied by means of osmometric and magnetic measurements. The mixed chain-ring-association can be explained satisfactorily assuming that two different dimers and four monomer species participate in the equilibria, including a monomeric diamagnetic ring. The equilibria existing between the different species are discussed. For the equilibria between the monomer and dimer species, which can be detected in solutions of normal viscosity by means of ESR-measurements, the unexpected values of ΔH=0 for the enthalpie of association and ΔS= +19.7 e. u. for the entropie of association were found.