bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Role of the Allosteric Sites in the X‐Ray Inactivation of Phosphorylase b
Authors: Damjanovich S. , Sanner T. , Pihl A. 
Published: March 2005

Crystalline rabbit muscle phosphorylase b was irradiated in dilute aqueous solution with X‐rays. The enzyme was inactivated with a G‐value of 0.09.Measurements of the Km values of the substrate, glucose‐1‐phosphate, and the allosteric activator, adenosine‐5′‐phosphate, demonstrated that these increased linearly with increasing radiation dose. The effect on the Km for the activator was 4 times greater than that on the Km for the substrate. The data indicate that the allosteric function is more sensitive to inactivation than the catalytic function.The enzyme SH‐groups were destroyed by X‐rays with a G‐value of 1.8. Comparison with data on the inactivation of the enzyme by sulfhydryl blocking agents demonstrated that the X‐ray destruction of sulfhydryl groups was sufficiently large to account for the X‐ray inactivation of the enzyme.Blocking of two SH‐groups with pCMB reduced the radiosensitivity of the enzyme by a factor of 2. Measurement of the Km values showed that the pCMB blocking protected preferentially the allosteric sites.The data indicate that the inactivation of phosphorylase b, both by sulfhydryl agents and by X‐rays, involves largely an effect on the allosteric sites with loss of ability to bind the essential activator and consequent loss of ability to bind substrate.
Effect of Irradiation in vitro on Mitochondrial Metabolism
Authors: Clark J. B. 
Published: March 2005

The ability of rat liver mitochondria to oxidise β‐hydroxybutyrate, succinate, α‐oxoglutarate, pyruvate, glutamate and isocitrate has been studied after irradiating the mitochondria in vitro with radiation doses within the range 0–100 krads.
The P/O (P/2e) ratio and the respiratory control, as well as the various mitochondrial respiratory states, have been examined by use of the oxygen electrode.
The P/O ratios of mitochondria oxidizing β‐hydroxybutyrate and succinate fell by 10% after a 100 krads dose of irradiation; after the same dose the P/O ratio with glutamate or pyruvate fell by 20% with α‐oxoglutarate 25% and with isocitrate 30%.
In all cases except isocitrate, the respiratory control fell more dramatically than the P/O ratio after irradiation. After 100 krads dose of irradiation the respiratory control of mitochondria oxidizing succinate fell by 20%; isocitrate by 30%; pyruvate or glutamate by 34%; β‐hydroxybutyrate by 37% and α‐oxoglutarate by 42%.
The results are discussed with respect to the normal control of mitochondrial citric acid cycle oxidations, the role that the structural integrity of the mitochondrion plays therein and the effects of irradiation on cellular systems in general.
Sur quelques constituants lipidiques de Corynebacterium ovis
Authors: Lacave C. , Asselineau J. , Toubiana R. 
Published: March 2005

The lipids of Corynebacterium ovis (strain Bl/50) were successively extracted by petroleumether, ethanol‐ether (1:1, v/v) and chloroform.The bulk of the petroleum‐ether extract consists mainly of sodium corynomycolate together with sodium salts of C14, C16 and C18 fatty acids. Some triglycerides and free fatty acids were also detected.Isolated from the ethanol‐ether extract were: hydrocarbons, palmitone, free corynomycolic acid, a small amount of free corynomycolenic acid and a peptidolipid fraction. The phospholipid fraction contains a mixture of closely related compounds, having about 3.5% P. By hydrolysis, they are split into lipid components (50–70% of the initial products; mixtures of C16 and C18 fatty acids and corynomycolic acid), and water soluble components (glycerol, glycerophosphoric acid, inositol, arabinose, and small amounts of amino acids).Complex substances, soluble in ether, having a high content of phosphorus (3.2 to 4.5%) were isolated from the chloroform extract. All of them contain glycerol, along with ethanolamine and sugars (glucose, galactose, arabinose, and a fast moving unidentified sugar) in one case, and with amino acids (chemically bound) in two other cases. Moreover, one third of the chloroform extract is made of a fraction (10.8% N and 1.3% P) insoluble in ether, which gives, by hydrolysis, 19% of lipid components and a polypeptide containing all the usual amino acids; the structure of this last fraction is discussed.
Biosynthesis of Mustard Oil Glucosides:
Authors: Underhill E. W. 
Published: March 2005

Apart from certain amino acids none of the nitrogenous intermediates involved in the biosynthesis of mustard oil glucosides have, untl now, been determined. Results consistent with the hypothesis — amino acids → aldehyde oximes → mustard oil glucosides — are presented for glucotropaeolin and gluconasturtin.Administration of dl‐[2‐14C]phenylalanine and [1‐14C]phenylacetaldehyde oxime to Tropaeolum majus L. shoots resulted in a greater incorporation of the tracer from the latter into the aglycone moiety of glucotropaeolin; incorporation of 14C from phenylacetaldehyde oxime into the aglycone was without randomization. Radioactive phenylacetaldehyde oxime was isolated from T. majus shoots which were fed dl‐[2‐14C]phenylalanine.The extent of conversion of 14C into the aglycone of gluconasturtin was similar when 3‐phenyl[1‐14C]propionaldehyde oxime and dl‐2‐amino‐4‐phenyl[2‐14C]butyric acid were fed to Nasturtium officinale R. Br. There was no randomization of labelled carbon in gluconasturtin aglycone derived from 3‐phenylpropionaldehyde oxime.
Zur Bildung von Chinolinalkaloiden in Pflanzen
Authors: Luckner M. 
Published: March 2005

Within the last few years, the quinoline alkaloids viridicatine (I), viridicatol (II) and 3‐O‐me thyl viridicatine (III) have been isolated from the mycelium and culture medium of Penicillium cyclopium Westling, Penicillium puberulum Bainier and Penicillium viridicatum Westling. Two further alkaloids found in the culture medium of P. cyclopium und P. viridicatum, cyclopenine (IV) and cyclopenol (V) are benzodiazepine derivatives. We have shown, using labelled precursors with P. viridicatum strain V41 and P. cyclopium strain SM72 that cyclopenine, cyclopenol, viridicatine and viridicatol are synthesised from anthranilic acid and phenylalanine. These results, together with the easy conversion of cyclopenine and cyclopenol into viridicatine and viridicatol respectively by means of acid or alkali, suggested that an in vivo relationship could exist between these two groups of alkaloids.In this paper we show that cyclopenine and cyclopenol are intermediates in the formation of viridicatine and viridicatol and that the transformation of the former to the latter is effected by an enzyme which we have named cyclopenase. This transformation occurs with fresh homogenised mycelium, with dried lyophilised mycelium and with mycelium free extract, that with the dead mycelium being much faster than with the other preparations. Using the mycelium free extract it was shown that the “agent of activity” depends upon pH, is not dialysable and can be destroyed by heating at 60° for 3 min, thus indicating the enzymatic nature of the transformation. Additional products of the transformation are carbon dioxide and methylamine.Cyclopenase activity is shown to be strongest in the surface cultured mycelium of P. viridicatum, strain V41. In the surface cultured P. cyclopium, strain SM72 mycelium the activity was much less and in the submerged culture of both strains practically no activity was detected. This agrees with the observation that, under normal conditions, only P. viridicatum strain V41 produces an appreciable amount of viridicatine and viridicatol.These experiments, together with previous work, indicate that anthranilic acid and a phenylpropane (e.g. phenylalanine) combine to give the benzodiazepines, cyclopenine and cyclopenol and these are transformed by the enzyme cyclopenase to the quinoline derivatives viridicatine and viridicatol. The detailed mechanism of this transformation is being investigated.
Immunochemistry of K Antigens of Escherichia coli
Authors: Hungerer D. , Jann K. , Jann B. , ØRskov F. , ØRskov I. 
Published: March 2005

An acidic polysaccharide which consists of glucuronic acid, galactose and mannose in a molar ratio of 1:1:1, and which contains 2.5%O‐acetyl groups, was isolated from Escherichia coli O 9:K 30:H 12 cells.Half the amount of the acidic polysaccharide present on the cell surface was extractable with saline at 60°. The residual polysaccharide was solubilized with 45% phenol at 65°. Purification of the two fractions was obtained by cetavlon precipitation.Saline‐extractable and non‐extractable polysaccharide fractions were identical with respect to chemical composition, serological specificity, pK value, neutral equivalent and intrinsic viscosity.In the ultracentrifuge, the non‐extractable polysaccharide showed one peak, wheareas the saline‐extractable fraction was inhomogenous. After treatment with diluted alkali a homogenous form of smaller particle size was obtained from both polysaccharide fractions. Alkali treatment did not alter the sugar composition of either fraction. The molecular weight of the alkali‐treated polysaccharide is about 150,000.The acidic polysaccharide was oxidized by sodium periodate with concomitant destruction of the glucuronic acid. Galactose and mannose in the polysaccharide chain were resistant to periodate oxidation.Acid hydrolysis gave rise to 3‐O‐β‐d‐glucuronosyl‐d‐galactose, which could be isolated in about 25% yield. No further oligosaccharides were detected in hydrolysates of the acidic polysaccharide.Acid hydrolysis of the polysaccharide in which the carboxyl groups had been reduced gave rise to glucosyl‐galactose and a second disaccharide which consisted of mannose and glucose, the latter being obtained at very low yield.It is concluded that the acidic polysaccharide of E. coli O 9:K 30: H 12 consists of linear subunits of a molecular weight of about 150,000. These subunits are joined through ester bonds between carboxyl groups of glucuronic acid residues and hydroxyl groups of sugar moieties. It is suggested that the trisaccharide mannosyl‐1,2‐glucuronosyl(β)1,3‐galactose is the repeating unit of the polysaccharide chain.The acidic polysaccharide has a high affinity for the surface of red blood cells. In passive haemagglutination tests the polysaccharide‐sensitized red cells react strongly with E. coli O 9: K 30: H 12 anti OK and anti K serum but not with anti O serum.After absorption of anti OK serum with the purified acidic polysaccharide the antiserum no longer agglutinates the encapsulated strain. The acidic polysaccharide is precipitated by K 30 antiserum. This precipitation is inhibited by glucuronic acid, β‐phenyl glucuronide and 3‐O‐β‐d‐glucuronosyl‐d‐galactose. After removal of the O‐acetyl groups the acidic polysaccharide shows reduced reactivity with K 30 antiserum. From these results we conclude that the acidic polysaccharide isolated from E. coli O 9: K 30:H 12 is the K antigen of this strain. The serologically determinant region of the K 30 antigen includes glucuronic acid and O‐acetyl groups.
pH‐abhängige magnetostatische und spektrale Eigenschaften des oxydierten Ferredoxins aus Clostridium pasterianum
Authors: Druskeit W. , Gersonde K. , Netter H. 
Published: March 2005

Oxidized ferredoxin from Clostridium pasteurianum has a well defined pH‐stability range. Irreversible change of spectral and magnetic properties occurs at pH < 3.7 and > 11.5.Spectral and magnetic properties undergo the same pH‐dependent changes. The curve of dissociation follows the behaviour of a dibasic acid and suggests the participation of at least two kinds of chelating protein‐groups in Fe‐binding, with apparent pK‐values at 4.0 and 10.5.Dissociation of the first proton in the acid range results in a decrease of the mean magnetic susceptibility per Fe‐atom reaching a minimum of = 1000 × 10−6 cgs units at pH 7.25. Dissociation of the second proton in the alkaline range results in an increase of the susceptibility and loss of typical absorption bands at 390, 300 and 280 nm.The magnetic data are discussed with regard to the assumption of two oxidation states of iron in oxidized clostridial ferredoxin.
Allosteric Properties of the Mg++‐Dependent Inorganic Pyrophosphatase in Mouse Liver Cytoplasm
Authors: Horn A. , Börnig H. , Thiele G. 
Published: March 2005

The Mg++‐dependent inorganic pyrophosphatase of the mouse liver is localized primarily in the cytoplasm. Substrate is the complex ion MgPPi2−; free PPi2−and MgADP are strong inhibitors, while Mg3+‐ions behave as an activator for the enzyme.The [Mg2+]/[substrate] ratio for optimum activity decreases with increasing substrate concentration. At substrate saturation and at pH‐optimum of 8.0, the optimum ratio is 10:1. Under these conditionsVmax= 3.7 μmole × min−1× mg protein−1, andKm= 1.6 × 10−5M.The enzyme shows allosteric properties of a K‐system with homotropic and heterotropic effects. Homotropic cooperative interactions with Hill coefficients of 2 have been shown for the substrate, the inhibitor MgADP, and the activator Mg2+. Under the influence of the substrate the cooperativity of the activator decreases, while that of the inhibitor increases, the cooperativity of the substrate itself decreases by means of the activator.If the enzyme is preincubated for 5 min at 40°, the allosteric cooperativity of the substrate is lost by desensitization. This effect is accompanied by a partial loss of activity. Pi4−> MgPP2−> Mg2+> MgADP protect the pyrophosphatase against heat inactivation.The possibility that the pyrophosphatase reaction follows the kinetics of a substrate‐activated enzyme, which is inhibited by free pyrophosphate, could be excluded.
Bile Acids in Portal Blood of Rats Fed Different Diets and Cholestyramine
Authors: Cronholm T. , Sjövall J. 
Published: March 2005

Dihydroxy and trihydroxy bile acids in the portal blood and intestinal contents of rats were analyzed by a gas chromatographic method. Cholic, hyodoxycholic, β‐muricholic, chenodeoxycholic and deoxycholic acids made up about 65, 13, 12, 5 and 5% respectively of the bile acids in portal serum. When a commercial pellet food was given about 65% of these acids were conjugated as compared with 90% when a low‐bulk semisynthetic diet was fed. The ratios between the different bile acids were similar in small intestinal contents and portal serum. The proportion of free bile acids and of hyodeoxycholic and deoxycholic acids was higher in portal blood draining the distal part of the intestine.The total bile acid concentration was about 60 μM with large variations partly due to sampling conditions. Cholestyramine, 1% in the diet, did not change the concentration or composition of the bile acids determined.The data obtained do not support the theory that the production of bile acids from cholesterol is regulated through a direct feedback inhibition by the bile acids returned to the liver via the portal blood.
Reaktivierung von Ammonium‐inaktivierter Glutaminsynthetase in Escherichia coli
Authors: Heilmeyer L. , Mecke D. , Holzer H. 
Published: March 2005

It is known from previous work that the regulation of Glutaminesynthetase in Escherichia coli is effected by two mechanisms. First, the synthesis of GS is repressed by NH4+; and secondly, the activity of GS is regulated by inactivation and reactivation of the enzyme molecule.In the present paper we demonstrate and characterize the reactivation of inactivated GS in intact cells of E. coli. GS is inactivated after addition of NH4+ to the culture medium. Experiments with a cell free extract from E. coli have shown, that the inactivation is mediated by a specific “inactivating enzyme”, ATP, Mg2+, and Glutamine which is probably formed from the added NH4+. The reactivation is observed, when the inactivated cells are centrifuged from the NH4+ containing medium and then resuspended in an NH4+ free medium. In about 5–7 minutes the activity increases 5–30‐fold.Inhibitors of protein synthesis such as chloramphenicol and p‐fluoro‐phenylalanine do not affect the reactivation proces. Only a slight retardation of the reactivation is observed.A carbon source is required for reactivation. When inactivated cells are incubated in a medium containing only salts and buffer no reactivation is observed. Probably the carbon source is metabolized to form intermediates and energy, which are needed for glutamine catabolizing reactions or for prevention of glutamine synthesis. Reactivation does not take place in the presence of NH4+i.e. under inactivating conditions. However if inactivation is inhibited by fluoride, reactivation can be observed in the presence of NH4+. When inactivated cells are incubated with fluoride only, without a carbon source in the reactivation medium, a reactivation is found.Inactivation as well as reactivation are inhibited by thiol‐group reagents. From these results we conclude that: (a) Reactivation is independent of protein synthesis; (b) Reactivation does not require energy; (c) Probably thiol‐groups are involved in the reactivation process.
The Chemical Composition of the Cytoplasmic Membrane of Bacillus subtilis
Authors: Bishop D. G. , Rutberg L. , Samuelsson B. 
Published: March 2005

The cytoplasmic membrane of Bacillus subtilis 168, prepared from cells in the stationary phase, has been found to contain protein (62%), RNA (22%) and lipid (16%).Analyses of the membrane lipid revealed the presence of phospholipids (75%), neutral lipid (10%) and a compound identified as a diglucosyl diglyceride. The major phospholipids were diphosphatidyl glycerol and phosphatidyl ethanolamine, with small amounts of phosphatidyl glycerol and lipoamino acids.Branched chain fatty acids comprised over 75% of the total fatty acids of both whole cells and membranes. Iso and anteiso acids with 15 and 17 carbon atoms were the major components, together with small amounts of iso acids containing 14 and 16 carbon atoms and n‐acids. No unsaturated acids were present.
Polysaccharide in vegetativen und aggregationsreifen Amöben von Dictyostelium discoideum
Authors: Malchow D. , Lüderitz O. , Westphal O. , Gerisch G. , Riedeal V. 
Published: March 2005

Amoebae of the cellular slime mold, Dictyostelium discoideum, were grown in submerged culture on the following bacterial strains which differ with respect to the sugar composition of their somatic antigens (lipopolysaccharides): Salmonella london S from containing Lipid A, 2‐keto‐3‐deoxyoctonate (KDO), heptose, glucose, galactose, mannose and rhamnose; the R mutant Escherichia coli B/r, containing Lipid A, KDO, heptose, and glucose; and the R mutant Salmonella minnesota R595 containing Lipid A and KDO. While the two R strains were phagocytized spontaneously by the amoebae, the S strain S. london had to be opsonized by specific antiserum to promote phagocytosis. The amoebae were harvested either at the end of the exponential growth phase or in the aggregation competent stage of their development, i.e. 8 to 9 hours after exhaustion of the food bacteria. The yields of amoebae were independent of the bacterial strain used for cultivation and ranged from 30 to 40 g per 100 g of bacteria (dry weight).Amoebae and supernatant media (after dialysis) were extracted by the phenol‐water method and the water‐soluble extracts obtained were fractionated by centrifugation at 100,000 ×g (sediment: S fraction; supernatant: L fraction). No significant yields of lipoplysaccharide were obtained either from amoebae or from the culture media. However, substances with the serological specificity of the lipopolysaccharides of the food bacteria were detected in the L fraction of the amoebae during the growth phase and of the culture medium after food exhaustion. Gel filtration of these fractions as well as gaschromatography and quantitative determinations of their sugar constituents showed that these specific substances represent the polysaccharide moiety of the bacterial lipopolysaccharides. β‐Hydroxymyristic acid which is a main constituent of lipid A was absent from the polysaccharides and could also not be detected in amoebae or culture media.Besides bacteria‐specific polysaccharides the amoebae contained additional polysaccharides with sugars which are not present in the food bacteria, such as l‐fucose and d‐mannose. These amoebae‐specific substances are the subject of further studies.
The Synthesis of Phosphoenolpyruvate in the Gluconeogenesis
Authors: Felicioli R. A. , Gabrielli F. , Rossi C. A. 
Published: March 2005

Livers of chick embryos at different stages of incubation have been fractionated into mitochondrial and “soluble” fractions by centrifugation.The pyruvate carboxylase and phosphoenolpyruvate carboxykinase activities, which constitute the major pathway for the synthesis of phosphoenolpyruvate, have been measured in both preparations.The pyruvate carboxylase activity occurs only in the mitochondria and parallels the gluconeogenetic ability.The bulk of phosphoenolpyruvate carboxykinase activity appears in the mitochondria. Only traces can be detected in the “soluble” fraction. The level of the mitochondrial phosphoenolpyruvate carboxykinase activity varies during the incubation period in accordance with its presumed role as a major source of phosphoenolpyruvate in the gluconeogenesis.The hypothesis that the pathway of synthesis of phosphoenolpyruvate in the process of gluconeogenesis is mainly located in the mitochondria of chick embryo liver is proposed.
A Fraction of Newly Synthesized DNA of HeLa Cells
Authors: Levis A. G. , Krsmanovic V. , Miller‐Faures A. , Errera M. 
Published: March 2005

HeLa cells were labelled for 10 or 30 minutes with [3H]thymidine and the DNA fractionated with chloroform‐isoamylalcohol; almost 90% of the labelled DNA remained in the interphase whilst about 60% of total DNA (bulk) was extracted in the aqueous phase.When added to a column of methylated serum albumin adsorbed on kieselguhr the extracted DNA was eluted as a major labelled peak with 0.8 M NaCl but a small fraction could only be eluted at higher NaCl concentrations. This “tail” contained both bulk and recently labelled DNA.After a short pulse the specific activity of the DNA eluted at higher salt concentrations increased; this was confirmed when pooled fractions were concentrated on a caesium sulphate gradient.Electron microscopy and sucrose gradient centrifugation of fractions recovered on a Cs2SO4 gradient shows that the eluted DNA was polydisperse (peak at about 18 S) with molecular dimensions of a few to almost 20 μ.When [3H]uridine was used as a label, both labelled DNA and rapidly labelled RNA could be studied simultaneously in the same way: these experiments indicated that in the fractions analysed, the radioactivity due to RNA and to DNA was not carried on the same molecules, suggesting the mutual exclusion of replication and transcription.