bluuebunny/crossref_metadata_2025_split huggingface dataset:
Spectrum and Iron Content of Protein B2 from Ribonucleoside Diphosphate Reductase
Authors: Brown N. C. , Eliasson R. , Reichard P. , Thelander L. 
Published: March 2005

Protein B2, one of the two non‐identical subunits of ribonucleoside diphosphate reductase from Escherichia coli B, contains two atoms of inorganic iron per molecule of protein. The metal could be removed from the protein either by prolonged dialysis against 8‐hydroxyquinoline or by precipitation with acid ammonium sulphate. This resulted in loss of enzyme activity which was recovered after treatment of the apoprotein with Fe2+ or Fe3+ but not with any other metals tested. Removal of iron did not change the behaviour of the apoprotein on sucrose gradient centrifugation or on polyacrylamide gel electrophoresis as compared to native protein B2.No “labile sulphide” could be demonstrated in protein B2.Protein B2 had a characteristic spectrum with a very sharp peak at 410 nm, a broader one around 360 nm and a steep shoulder at approximately 325 nm. The two peaks disappeared on removal of iron and reappeared on reactivation of the enzyme with the metal.When protein B2 was treated with hydroxyurea or hydroxylamine the peak at 410 nm (but not that at 360 nm) disappeared in parallel with enzyme activity. Such treatment did not result in the removal of iron.It is suggested that the very sharp peak at 410 nm originates from an unidentified component of protein B2. Furthermore, this component, together with iron, may be the functional equivalent in the E. coli system of cobamide coenzyme in ribonucleoside triphosphate reductase of Lacto‐bacillus leichmannii.
The Effect of Diethylether upon the Function of the Vesicles of Sarcoplasmic Reticulum
Authors: Fiehn W. , Hasselbach W. 
Published: March 2005

The calcium permeability of the sarcoplasmic vesicles is greatly increased when vesicular suspensions are extracted with ether.
A 7–8% v/v aqueous ether solution abolishes the calcium concentrating ability of the vesicles completely. The calcium remaining in the solution permanently activates the calcium magnesium dependent ATPase.
In parallel to the change of the permeability of the vesicular membranes membranal lipids are removed by the ether treatment. Concentrations of ether which produce a maximal permeability increase only extract cholesterol esters. Higher concentrations of ether which inhibit the transport ATPase remove neutral lipids and phospholipids. The basic ATPase is not affected.
Urate Oxidase in Primate Phylogenesis
Authors: Christen Philipp , Peacock Wendell C. , Christen Anita E. , Wacker Warren E. C. 
Published: March 2005

Several genera of New World monkeys have high uric acid concentrations in serum and urine comparable to man and the higher apes. Like man these animals lack urate oxidase activity in liver tissue. The purine metabolism of these non‐human primates appears to be similar to that of man as exemplified by fasting‐induced hyperuricemia. These South American monkeys should provide an easily accessible experimental system for the study of purine metabolism in a species closely related to man.
Old World monkeys and prosimians have low uric acid concentrations in serum and urine. The urate oxidase activity of prosimian liver is remarkably stable whereas that of Old World monkeys was found to be quite unstable, a probable reflection of the gradual degeneration of this enzyme in primate phylogenesis.
The Properties of Mitochondria Enriched in vitro with Cholesterol
Authors: Graham J. M. , Green C. 
Published: March 2005

The unesterified cholesterol content of rat liver mitochondria can be raised from 0.04—0.06 to 0.1—0.13 μg per μg phospholipid by incubation for 16 h at 25° with plasma lipoproteins.
The extra cholesterol taken up by the mitochondria is roughly equally divided between outer and inner membrane fractions.
The NADH oxidase, rotenone‐insensitive, NADH‐cytochrome c reductase, fatty acid oxidase and monoamine oxidase activities of cholesterol‐enriched mitochondria are similar to those of control mitchondria stored at 4° for 16 h.
Dinitrophenol‐stimulated, Mg2+‐dependent ATPase and respiratory control measurements indicated that the functional integrity of the cholesterol‐enriched mitochondria is as good as that of the control mitochondria although in both respiratory control is less marked than in freshly‐isolated mitochondria.
Succinate‐cytochrome c reductase activity is much greater in cholesterol‐enriched than in control mitochondria. When the mitochondrial cholesterol level is alternately raised and lowered, the succinate‐cytochrome c reductase activity increases and decreases with it.
Cholesterol‐enriched mitochondria are much more resistant to large amplitude swelling than control mitochondria, apparently because of the increased strength of the outer membrane.
The changes in light absorbance associated with small‐amplitude swelling and shrinking of cholesterol‐enriched mitochondria are much smaller than those of control mitochondria.
Thyroid Cytoplasmic Ribonucleoprotein Particles of Very High Size Containing Messenger‐Like and Ribosomal Ribonucleic Acids
Authors: Lissitzky S. , Poirée J.‐C. , Cartouzou G. , Grégoire J. 
Published: March 2005

Cytoplasmic giant‐size ribonucleoprotein particles has been purified from the deoxycholate treated 15000 ×g supernatant of sheep thyroid slices incubated in the presence of [3H]uridine for 0.5 to 8 hours. After treatment of unclarified polyribosomes with 10 mM EDTA, 400 to 1000 S ribonucleoprotein particles have been isolated free of ribosomal subparticles by differential sedimentation. They are heterogeneous in size and buoyant density in CaCl gradients (from 1.38 to 1.52 g/ml, with maxima at 1.52, 1.46, and 1.42).Polyribosome‐associated 400 to 1000 S ribonucleoprotein particles deprived of free ribosomal subparticles contain messenger‐like and ribosomal RNA as shown by the rate of labelling and sucrose gradient centrifugation, polyacrylamide gel electrophoresis and base composition.Particle proteins obtained by 3 M LiCl‐6 M urea treatment separate in polyacrylamide gel electrophoresis into 3 to 4 basic components which disclose the same electrophoretic mobility as some ribosomal proteins. These 3 to 4 protein bands are distinct from total thyroid soluble proteins and from histones. Similar protein species are present in ribonucleoprotein particles diffusing spontaneously from thyroid nuclei in vitro.The artifactual formation of these structures during EDTA exposure or slice incubation has been rendered unlikely by appropriate controls. Although tentative, the possible physiological significance of these particles is briefly discussed.
The Effect of Uncouplers of Oxidative Phosphorylation on Oxygen Uptake, Ubiquinone Redox Status and Energy‐Rich Phosphate Levels of Isolated Atria*
Authors: Lechner V. , Siess M. , Hoffmann P. C. 
Published: March 2005

The effects of 2,4‐dinitrophenol and carbonyl‐cyanide‐m‐chlorophenylhydrazone on contractile amplitude and frequency, oxygen consumption, and ubiquinone redox status have been examined in spontaneously‐beating isolated guinea pig atria incubated with glucose. Dinitrophenol (2 to 100 μM) and carbonylcyanide‐chlorophenylhydrazone (0.02–0.4μM) lead to depression of contractile amplitude to 10% of control values accompanied by decreases in oxygen consumption of up to 20%. The ubiquinone redox status was shifted maximally from 32–35% oxidized ubiquinone to 66% by dinitrophenol and to 57% by carbonylcyanide‐chlorophenylhydrazone.The effect of dinitrophenol on oxygen consumption and ubiquinone redox status was further examined in non‐beating atria (low Ca++) incubated with glucose, malate or pyruvate. With glucose dinitrophenol led to a depression of oxygen consumption, while with malate or pyruvate a stimulation to 219% and 235% of the predrug level, respectively, was observed. At 100 μM dinitrophenol, ubiquinone redox status was shifted to the oxidized side and correlated with the rate of respiration with all three substrates. At lower concentrations of dinitrophenol, ubiquinone was oxidized to a lesser extent with malate while no significant shift was observed with pyruvate or glucose.Levels of creatine phosphate, ATP and pyruvate were decreased with increasing concentrations of dinitrophenol in non‐beating atria incubated with glucose and malate. No significant difference in these effects was detected with regard to substrate, although the trend indicated that the levels of these three compounds were more sensitive in atria incubated with glucose. Lactate levels were unaffected with low concentrations of dinitrophenol and elevated at 100 μM regardless of substrate.It was concluded that the effect of uncouplers of oxidative phosphorylation on ubiquinone redox status and oxygen consumption in intact atria is dependent upon contractile activity and exogenous substrate. However, the responses expected from studies with isolated mitochondria, namely, stimulation of oxygen uptake and ubiquinone oxidation over a range of dinitrophenol concentrations, can be obtained in non‐contractile atria incubated with malate.
Molecular Weight and Quaternary Structure of Yeast l‐Lactate Dehydrogenase (Cytochrome b2)
Authors: Pajot P. , Groudinsky O. 
Published: March 2005

A new determination of the extinction coefficient of the Soret band of reduced cytochrome b2 provides a value of 183 mM−1cm−1 instead of the generally accepted figure of 232. Four methods were used: pyridine hemochromogen, dicyanide complex, spectrum in formic acid and iron titration.No significant differences are observed in the heme spectral properties of cytochrome b2 and its low molecular weight derivative “cytochrome b2 core”.
Dry weight associated with iron and heme content determinations lead to a minimal molecular weight per heme of 58600. This result combined with hydrodynamic and crystallographic studies by other authors allows one to propose a tetrameric structure for cytochrome b2.
Isolation, Purification and Physico‐Chemical Characteristic of Shigella sonnei Phase I Free Endotoxin
Authors: Romanowska E. , Pelczarska A. , Wnuk W. , Mulczyk M. , Godzińska H. , ŠLopek S. 
Published: March 2005

The specific extracellular material with endotoxic properties (free endotoxin) was isolated from liquid culture of Shigella sonnei phase I.Bio‐Gel P‐300 filtration and subsequent ultracentrifugation at 10500μg was used to purify and separate free endotoxin into two fractions: the sediment and the supernatant.The sediment fraction was identified as lipopolysaccharide‐protein complex of the molecular weight of several millions, containing the same constituents as cell lipopolysaccharide of Shigella sonnei phase I, prepared by phenol–water extraction. This substance was a better endotoxin than cell lipopolysaccharide; it showed strong toxicity (L.D.50= 15 μg), pyrogenicity and elicited local and general Shwartzman reaction.The supernatant fraction represents phase I specific substance practically free of heptose, 2‐keto‐3‐deoxyoctonic acid and phosphorus. It contained glucose, galactose and glucosamine as does phase I lipopolysaccharide, and also galactosamine and small amounts of mannose. Phase I specific substance was very active serologically and revealed very weak endotoxic properties (L.D.50= 1800 μg). The homogeneity of the supernatant fraction was proved in sedimentation experiments, free electrophoresis and rechromatography on Bio‐Gel P‐300 and Sephadex G‐200 columns. The examination of hydrodynamic properties (sedimentation coefficient, limiting viscosity number, diffusion constant and partial specific volume) of the supernatant fraction showed that this substance has a linear structure with molecular weight 90800, and diameter and length of the molecule of about 15 Å and 800 Å, respectively.
Choline Esters, their Precursors and Metabolites in the Hypobranchial Gland of Prosobranchiate Molluscs, Concholepas concholepas and Thais chocolata
Authors: Roseghini Marisa , Erspamer Vittorio , Luis Ramorino M. , Gutierrez J. E. 
Published: March 2005

Extracts of the hypobranchial body of two prosobranchiate molluscs of the Muricidae family were examined for their content of choline esters, as well as of precursors and metabolites of these esters.The hypobranchial gland of Concholepas concholepas contained, in addition to large amounts of urocanylcholine (murexine) and senecioylcholine, appreciable amounts of free choline, free urocanic acid and ethyl urocanate. All these compounds, and especially the choline esters, were predominantly localized in the dye‐secreting area of the hypobranchial gland. As much as 3% of the wet weight of the purple area was accounted for by murexine and seneciocylcholine.The only choline ester found in the hypobranchial body of Thais chocolata was senecioylcholine; derivatives of urocanic acid were lacking.The occurrence of ethyl urocanate in the hypobranchial gland of Concholepas concholepas demonstrates that not only choline but also other alcohols may be esterified by urocanic acid.
Inhibition of Brain Glutamate Decarboxylase by Adenosine Triphosphate
Authors: Turský Timotej 
Published: March 2005

ATP acts as an inhibitor of brain glutamate decarboxylase in a water brain tissue extract with low ATPase activity. This inhibition is not caused by competition of ATP with glutamate or pyridoxal‐5‐phosphate.The concentration of ATP, which causes a 50% inhibition of glutamate decarboxylase, [I]50%, depends on the pyridoxal‐5‐phosphate concentration. At 15 μM pyridoxal‐5‐phosphate the [I]50% is 0.3 mM ATP. At 75 μM pyridoxal‐5‐phosphate the [I]50% is 1.3 mM ATP. AT 375 μM pyridoxal‐5‐phosphate glutamate decarboxylase is not inhibited to 50% even with 10 mM ATP.ADP, GTP and UTP are strong inhibitors of glutamate decarboxylase at high concentration. At lower concentrations ATP is the most potent inhibitor. AMP and adenosine do not effect glutamate decarboxylase, nor do they affect the inhibitory action of ATP.Inorganic phosphate in concentrations of 5—40 mM does not influence the activity of glutamate decarboxylase. At the same concentrations Pi diminishes the inhibitory effect of ATP. The [I]50% increases from 0.3 mM ATP (without Pi) to 1.7 mM ATP in the presence of 20 mM Pi.
Interference of Ethanol and Sorbitol with Hepatic Ketone Body Metabolism in Normal, Hyper‐ and Hypothyroid Rats
Authors: Lindros Kai O. 
Published: March 2005

Rats pretreated with triiodothyronine or propylthiouracil were compared with normal rats with respect to the changes induced by ethanol or sorbitol in the levels of ketone bodies and acetyl coenzyme A and in the mitochondrial redox state of the NAD couple in the intact liver after overnight fasting.
A single dose of ethanol (2.5 g/kg) increased the ketone body level and the acetyl‐CoA content after 75 min in both normal and hyperthyroid rats but not in hypothyroid rats.
Infusion of sorbitol (0.5 g/kg) resulted in decreases in both ketone formation and levels of acetyl‐CoA after 15 min in all types of rats.
The β‐hydroxybutyrate/acetoacetate ratio, which represents the redox state of the NAD couple in the mitochondria, was increased more than three‐fold by treatment with ethanol in normal rats, but only by 50% in hyperthyroid rats. A ten‐fold increase in the redox state of the mitochoondia was caused by ethanol in hypothyroid rats, as the result of a strongly diminished acetoacetate level.
Sorbitol infusion resulted in slight increase of the β‐hydroxybutyrate/acetoacetate ratio in normal and hypothyroid rats but decreased the ratio in hyperthyroid rats.
The different ketone body levels observed in these situations were not found to be related to changes in the mitochondrial redox state, but a highly significant correlation (P < 0.001) was observed between the changes in the content of acetyl‐CoA and the ketone bodies.
Structure des acides corynomycoliques de Corynebacterium hofmanii et leur implication biogénétique
Authors: Welby‐Gieusse M. , Lanéelle M. A. , Asselineau J. 
Published: March 2005

The three main components of the mixture of corynomycolic acids (α‐branched, β‐hydroxy acids of the general formula R1—CHOH—CHR2—COOH) isolated from a strain of Corynebacterium hofmanii are:C32H64O3 (corynomycolic acid); C34H66O3 (corynomycolenic acids); C36H68O3 (corynomycoldienic acid).By thin‐layer chromatography on silver nitrate‐impregnated Silicagel G, we were able to separate the hydroxy acids having 0, 1 or 2 double bonds. The pyrolytic chromatography of their methyl esters indicates that the mono‐unsaturated acids form a mixture of C34‐acids containing the double bond either in the main chain or in the side chain; the di‐unsaturated acid fraction is constituted solely by a C36‐acid with a double bond in each fragment arising from pyrolysis.By oxidative cleavage, we find that the position of the double bond is 9, 10 (as in oleic acid). According to the nature of the main chain (aldehyde fragment of pyrolysis) and of the side chains (ester fragment of pyrolysis), some suggestions are made about the selective use of fatty acids in the biosynthesis of corynomycolic acids.
Fluctuation of Hepatic Enzymes Important in Glucose Metabolism in Relation to Thyroid Function
Authors: Böttger I. , Kriegel H. , Wieland O. 
Published: March 2005

Enzyme activities of pyruvate carboxylase, phosphoenolpyruvate carboxykinase, pyruvate kinase and of mitochondrial glycerolphosphate dehydrogenase were studied in the livers of rats under the following states of thyroid function: 131I‐thyroidectomized rats, 131I‐thyroidectomized rats treated with triiodothyronine, normal rats treated with excess of triiodothyronine, and normal untreated rats. In the thyroidectomized group all of the enzyme activities listed were significantly diminished. After treatment with a single dose of triiodothyronine the activities of pyruvate carboxylase and of pyruvate kinase were restored to normal whereas phosphoenolpyruvate carboxykinase and — most markedly — glycerolphosphate dehydrogenase were raised above the normal level. After repeated administration of triiodothyronine to normal rats a further increase in the activity of pyruvate carboxylase, phosphoenolpyruvate carboxykinase and of glycerolphosphate dehydrogenase was observed.The activities of glycerolphosphate dehydrogenase and of pyruvate carboxylase 70 h following triiodothyronine injection into hypothyroid rats were more than 50% lower after treatment with actinomycin C suggesting that the increase in enzyme activities was due to increased synthesis of enzyme protein. Phosphoenolpyruvate carboxykinase activity was not changed significantly by actinomycin C.The possible significance of these thyroid hormone dependent enzyme fluctuations in controlling the overall rate of hepatic gluconeogenesis is discussed.
Synthèse de RNA stables dans une souche d'Escherichia coli stringent pendant la carence en acide aminé spécifique
Authors: Galibert F. , Eladari M. E. , Larsen C. J. , Boiron M. 
Published: March 2005

By definition amino‐acid starvation of an RCstrEscherichia coli strain causes simultaneous arrest of RNA and protein synthesis. However, it has recently been demonstrated that under such conditions mRNA synthesis does not stop and this result showed that RNA synthesis is not a coordinated process. The present study, which was carried out to determine the effects of amino‐acid starvation on net RNA synthesis in an RCstrE. coli strain, has led to the following results:a) during amino‐acid starvation net RNA synthesis is reduced to about 5% of the normal level;b) ribosomal RNA appears in 50 S and 30 S ribosomes and in 38 S and 21 S particles which seem to be precursors of 50 S and 30 S ribosomes, respectively;c) analysis by chromatography on methylated albumin column and by electrophoresis on polyacrylamide gels shows that the 38 S particle is devoid of 5 S RNA;d) a 5 S RNA appears in the supernatant fraction of ribosome preparations. This RNA, which is slightly different from the true 5 S RNA, is called 5 S stringent RNA. With respect to its chromatographic behaviour on G‐100 Sephadex and methylated albumin column, its mobility on disc electrophoresis, it is identical to 5 S relax RNA and 5 S chloromycetin RNA which are synthesized when protein synthesis is blocked either by amino‐acid starvation of a RCrelE. coli strain or by addition of chloromycetin;e) from the relative quantity of the different classes of RNA it is concluded that RNA synthesis is not coordinated and from the appearance of rRNA in ribosomal particles, a mechanism concerning the regulation of RNA synthesis is proposed.
The Covalent Murein‐Lipoprotin Structure of the Escherichia coli Cell Wall
Authors: Braun Volkmar , Sieglin Uta 
Published: March 2005

After pronase treatment of the murein‐lipoprotein complex (rigid layer) of the cell wall of E. coli B or E. coli K12 (W 945), lysine and arginine remain as the sole amino acids covalently bound to the murein (peptidoglycan, glycopeptide). These amino acids occur in equimolar amounts, each equal to the amount of lysine remaining with the murein after trypsin digestion of the murein‐lipoprotein complex.From partial acid hydrolysates of such a murein, prepared by pronase digestion of the mureinlipoprotein complex, the following peptides have been isolated: (1) diaminopimelyl‐lysyl‐arginine; (2) alanyl‐glutamyl‐diaminopimelyl‐lysyl‐arginine; (3) glucosaminyl‐muramyl‐alanyl‐glutamyl‐diaminopimelyl‐lysyl‐arginine. Peptide 1 shows that the lipoprotein is bound by the α‐amino group of the presumbaly N‐terminal lysine to the carboxyl group of diaminopimelic acid. Peptide 2 consists of a peptide side chain of the murein to which the two amino acids of the N‐terminal end of the lipoprotein, lysine and arginine, are attached. Peptide 3 constitutes a repeating unit of the murein to which the peptide lysyl‐arginine of the lipoprotein is bound.The lipoprotein cleaved from the murein by a short trypsin digestion had an amino acid composition similar to the lipoprotein in the untreated murein‐lipoprotein complex and arginine as N‐terminal amino acid. The following structure is proposed: murein‐lysyl‐arginyl‐lipoprotein.In the rapid reaction of trypsin with the cell wall the enzyme apparently cleaves at the C‐terminal end of the lysime of the murein‐lipoprotein linkage which results in murein‐lysine and arginyl‐lipoprotein. Some cleavage at the C‐terminal end of arginine gives rise to free arginine (14%).These results support the supramolecular structure of the murein‐lipoprotein complex previously proposed. On the average one lipoprotein molecule is covalently bound to every tenth repeating unit of the murein from which an average distance of 103 Å between two lipoprotein molecules along the polysaccharide chains of the murein is deduced.
Kinetic Study of Yeast Hexokinase
Authors: Noat Georges , Ricard Jacques , Borel Maguy , Got Claude 
Published: March 2005

The ionic species ATP4− and Mg2+, at high concentrations, decrease the rate of glucose phosphorylation catalyzed by yeast hexokinase. A theoretical study of all the possible mechanisms (271 models) of this inhibition has been made. The comparison of these mechanisms with the experimental results shows that only one model can explain the inhibition of the reaction by ATP, and that only one can also explain the effect of the high magnesium concentrations.It was thus possible to show that the ionic species ATP4− can be bound on hexokinase and on the hexokinase‐glucose complex. Its affinity is much stronger for the second form of the enzyme than for the first. The complexes thus formed are devoid of any activity (“dead‐end” complexes). The inhibition of the hexokinase by the high nucleotide concentrations is therefore due to the formation of these complexes. A ternary chelate of the Mg(ATP)26− type does not exist.Magnesium possesses no affinity for the enzyme. Its role in the catalysis must therefore by indirect. The results presented agree with the idea that the metal polarizes the phosphoryl bond of the ATP that is split when glucose‐6‐phosphate is formed. Magnesium can form with ATP a ternary chelate of the Mg2ATP type, unable to be bound on the hexokinase. The inhibiting effect of high concentrations of the metal can be explained by the formation of this inactive ternary chelate and by the decrease in concentration of the MgATP2− complex.