bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Nature of the “Microfibrillar” Component of Elastic Fibers
Authors: Robert Barbara , Szigeti Marthe , Derouette Jean‐Claude , Robert Ladislas , Bouissou Hubert , Fabre Marie‐Thérèse 
Published: March 2005

Elastin was prepared from calf ligamentum nuchae with several methods using the following solvents for the extraction of extraneous (non‐elastin) proteins: 0.1 N NaOH at 100 °C, 88% formic acid at 45 °C, 70% trichloracetic acid at +4 °C, 5 M guanidine HCl with a thiol reagent and autoclaving in water. All elastin samples contained small amounts of carbohydrate. Electron microscopy showed the presence in all samples of electron‐translucent lamellae and osmiophilic uranyl‐lead stainable “microfibrillar” elements.The osmiophilic “microfibrils” decreased strongly in the elastin preparations after extraction with 8 M urea–0.1 M 2‐mercaptoethanol, 5 M guanidine–0.05 M dithiothreitol or 0.1 M Na2SO3. These solvents extracted a significant proportion of the hexose content of the elastin samples with only 6–7% of their protein content. Similar results were obtained with chymotrypsin digestion although this enzyme acts less selectively than the above mentioned solvents and degrades elastin also.When 125I‐labelled elastin was used for extraction with 8 M urea–0.1 M mercaptoethanol the extracted glycopeptides had a significantly higher specific activity than the residual elastin. These results suggest that the microfibrillar elements are derived from or are identical with the structural glycoproteins which were extracted from elastin‐rich tissues by identical procedures [12].The presence of glycoprotein in varying proportions in purified elastin preparations can explain the variation of its amino acid content (ratio of polar to non‐polar amino acids) with age or in certain pathological conditions (atheromatosis, emphysema) and some of its immunochemical properties (cross reactions with structural glycoproteins).
Equilibrium of the ATP:Glutamine Synthetase Adenylyltransferase Reaction
Authors: Wohlhueter Robert M. 
Published: March 2005

The activity of glutamine synthetase from Escherichia coli is regulated by an enzymecatalyzed adenylylation of a tyrosyl residue. The equilibrium of the adenylyl‐group transfer has been measured. Apparent ΔG°=−;1.8 kcal/mole (Keq= 19.6 at 25 °C, 10 mM MgSO4), implying that ΔG° for the hydrolysis of the tyrosyl‐O‐AMP bond is about 10 kcal/mole. Apparent enthalpy of the transfer reaction was estimated from the temperature dependence of the equilibrium constant; ΔH°app=−1.7 kcal/mole, ΔS°app∼ 0 cal deg−1 mole−1.Solutions for the distribution of the various ionic forms of ATP and pyrophosphate (protonated and magnesium‐complexed) present in the reaction mixtures have been obtained by computer. A model reaction written with MgATP, magnesium pyrophosphate, and the subunit of glutamine synthetase as the thermodynamic reactants provides the best interpretation of equilibrium data at various conditions of magnesium and hydrogen‐ion concentrations.
The Protection by 70 S Ribosomes of N‐Acyl‐aminoacyl‐tRNA against Cleavage by Peptidyl‐tRNA Hydrolase and its Use to Assay Ribosomal Association
Authors: Vogel Zvi , Vogel Tikvah , Zamir Ada , Elson David 
Published: March 2005

Free N‐carbobenzyloxy‐phenylalanyl‐tRNA is rapidly cleaved by the enzyme peptidyl‐tRNA hydrolase. When bound to a 30 S ribosome in the presence of poly(U), the substrate is hydrolyzed as rapidly as when free. The addition of 50 S ribosomal subunits to form the 70 S ribosomal binding complex protects the bound substrate from the enzyme. The degree of protection depends on the state of activity of the 50 S subunit. Under conditions favoring the formation of 70 S ribosomes, active 50 S subunits (capable of catalyzing the peptidyl transferase reaction) afford complete protection at one mole per mole of 30 S subunits. Inactive 50 S subunits also protect the substrate, but less effectively.The protection of bound substrate can be used to measure the amount of 70 S ribosomal binding complex formed and the rate of its formation. Using highly active hydrolase preparations, we have developed a rapid assay procedure and present several examples of its use. Under conditions favoring the association of ribosomal subunits, the formation of the 70 S complex may reach completion within a few seconds.
The Structure of Nucleohistone
Authors: Henson Patricia , Walker Ian O. 
Published: March 2005

The viscosity of histone‐depleted nucleohistone has been measured at high and low ionic strength. Native nucleohistone at low ionic strength and f1‐depleted nucleohistone at both low and high ionic strength all have the same intrinsic viscosity of 10.0 dl/g. This implies that these molecules are not flexible but behave in solution as rigid particles. On the assumption that they are rods they have a weight‐average length of 1160 ± 120 nm and diameter 5.6 ± 0.3 nm. The DNA is compressed in the rod to give an increase in mass per unit length for the DNA of 5.0 ± 0.5.By contrast the intrinsic viscosity of nucleohistone depleted of f1, f2a2 and 75% of F2b and F3, varies with ionic strength in the manner typical of a flexible polyelectrolyte. The shapes of the sedimentation boundaries measured at high ionic strength of depleted nucleohistone show that the dissociation of histone from DNA takes place so that all molecules are depleted to the same extent. It thus has a conformation intermediate between that of native nucleohistone and DNA.Polyacrylamide gel electrophoresis of histones removed by 1.0 M NaCl using a technique capable of resolving all five main histone fractions, shows that if one fraction only is responsible for supercoiling nucleohistone it must be f2a2.
Effects of 3,3′,5‐Triiodo‐l‐thyronine Administration on the Embden‐Meyerhof Pathway in the Kidney Cortex of the Rat
Authors: Meldolesi Maria F. 
Published: March 2005

The amount of lactate and pyruvate production by kidney cortex homogenates (cell sap and microsomal fraction) from all intermediates of the glycolytic pathway has been investigated in normal and 3,3′,5‐triiodo‐l‐thyronine‐treated rats.In normal animals the lactate and pyruvate production increases steadily from glucose (154 nmoles × mg protein−1× h−1) through phosphoenolpyruvate (31.850 nmoles × mg protein−1 h−1).The addition in vitro of triiodo‐l‐thyronine to kidney cortex homogenates has no significant effect on lactate production.In the animals treated for 5 days with 1 mg/kg body weight and per diem of triiodo‐l‐thyronine, the lactate and pyruvate formation from various intermediates of the Embden‐Meyerhof pathway is significantly (P < 0.01) increased: from glucose 225% of the control value, from glucose 6‐phosphate and fructose 6‐phosphate, 192%, from fructose 1,6‐bisphosphate and glyceraldehyde 3‐phosphate, 132%, and from 3‐phosphoglycerate and 2‐phosphoglycerate, 120%. No significant increase in lactate and pyruvate production has been observed using either phosphoenolpyruvate or pyruvate as substrates.
Studies on the Mode of Action of Oestradiol on Chicken Oviduct
Authors: Cox Ronald F. , Catlin Graham H. , Carey Norman H. 
Published: March 2005

Macromolecules which bind oestradiol‐17,β after incubation in vitro of oviduct tissue from immature chickens have been studied.
Analysis of cytoplasmic extracts and salt‐extracts of nuclei on sucrose density gradients demonstrate the presence of 10 S and 7 S components in cytoplasm and nucleus respectively which bind oestradiol‐17β. The cytoplasmic component was not dissociated by 0.5 M KCl. Neither of these components was present in extracts isolated from chicken spleen, nor in chicken plasma.
Kinetics of binding of oestradiol to cytoplasmic and nuclear components were studied at 37°C. The rate of formation of cytoplasmic complexes was biphasic; it accumulated rapidly at fist (0–1 h) and more slowly at later times (1–4 h). Nuclear complex accumulated gradually between 0–4 h.
Precipitation of oestradiol‐bound cytoplasmic complex with protamine sulphate was used to estimate the number of binding sites in the cytoplasmic extract and the dissociation constant of the complex. Values obtained were 2.6 pmoles/mg protein and 9.3 pM, respectively. Binding sites of correspondingly high affinity for oestradiol‐17β were not detected in chicken liver cytoplasm.
Radioactivity associated with both 10 S and 7 S complexes was identified as almost entirely (98%) oestradiol‐17β. Nucleases had little effect on the integrity of the complexes; pronase destroyed the complexes.
Competition studies with unlabelled steroids were carried out to determine their relative affinity for both cytoplasmic and nuclear components as compared with oestradiol–17β. Both macromolecules exhibited high affinity for diethylstilboestrol (approximately 100% competition). Progesterone, testosterone and oestrone showed less than 11%, competition for the nuclear component. These steroids exhibited 34%, 8%, and 20% competition respectively for the cytoplasmic component. Oestradiol‐17α does not compete for either receptor.
The ultrastructural changes occurring in immature chicken oviduct epithelial cells after brief oestrogen treatment in vivo are described. However, 10S and 7S complexes have not yet been detected after administration of oestradiol‐17βin vivo.
The Influence of the Dimerisation on the Stoichiometry of the Active Center in Ferredoxin from Clostridium pasteurianum
Authors: Gersonde Klaus , Trittelvitz Eberhard , Schlaak Heinz‐Eberhard , Stabel Hans‐Henning 
Published: March 2005

Determinations of the molcular weight by aid of gel filtration demonstrate that ferredoxin from Clostridium psteurianum can exist as well in a monomeric (Mr= 6000) as in a dimeric form (Mr= 12000). The dimerisation takes place in the presence of oxygen. Using exactly anaerobic conditions pure monomeric material can be prepared; using aerobic conditions, however, pure dimeric material or a mixture of monomers, dimers, and apoferredoxins of higher molecular weights appear.Comparing the analytical data of the active center one finds eight atoms of iron and labile sulfur in monomeric ferredoxin, whereas four atoms of iron and labile sulfur are found in the sub‐unit of dimeric ferredoxin.Results of the determination of the Hg‐content in mersalyl‐apoferredoxin prepared from a dimeric sample and of the titration of free SH‐groups in monomers and dimers can be explained assuming that four cysteinyl residues per subunit participate in disulfide bridges in dimeric ferredoxin. That means, dimerisation is accompanied by a loss of iron and labile sulfur and therefore by a decrease of the absorption coefficient ɛ390= 30000 M−1× cm−1 to E390= 15000 M−1× cm−1 related to one subunit with the molecular weight of 6000. The ratio of absorbances A390: A280 seems to remain unchanged.In the phosphoroclastic system the biological activity of the dimeric ferredoxin decreases by a factor of two referring to one subunit.
Incorporation in vitro of [14C]Leucine into the Mitochondrial Protein of Lucilia cuprina
Authors: Williams Keith L. , Birt L. Michael 
Published: March 2005

The basic requirements for incorporation in vitro of [14C]leucine into sterile mitochondria isolated from thoracic flight muscles of newly emerged Lucilia cuprina (the Australian sheep blowfly) have been studied in detail. Particular attention has been given to the influence of bacterial contamination on the incorporation.The incubation medium developed has the following composition: (final concentrations) 18 mM MgSO4; 1 mM EDTA; 10 mM potassium phosphate; 50 μM each of 19 amino acids (excluding leucine); 65 mM KCl; 10mM HEPES (N‐2‐hydroxyethylpiperazine‐N′‐2‐ethane sulfonic acid) buffer; pH optimum7.4 (ATP‐generating system) or 8.0 (dl‐α‐glycerophosphate as substrate); and either ATP‐generating system (4 mM ATP, 5 mM phosphoenolpyruvate, 20 μg pyruvate kinase) or substrate‐supported system (20 mM dl‐α‐glycerophosphate + 4 mM ADP). This medium is similar to that used for investigation of amino acid incorporation by mitochondria from the tobacco hornworm, but different from that used with locust mitochondria, especially in having a higher Mg2+ content, higher pH optimum and lower amino acid mixture content.
The Transport of Citric‐Acid‐Cycle Intermediates in Rat‐Liver Mitochondria
Authors: Papa Sergio , Lofrumento Nicola E. , Kanduc Darja , Paradies Giuseppe , Quagliariello Ernesto 
Published: March 2005

The electrical nature of the malate‐citrate, malate‐Pi and malate‐2‐oxoglutarate exchange diffusion reactions in rat liver mitochondria has been studied. The exchanges have been followed in the presence of respiratory inhibitors and oligomycin to suppress energy supply.
The study of the effect of ionophores and uncouplers on the exchange‐diffusion reactions indicates that the citratein‐malateout and the malatein‐Pi,out exchanges are stimulated by inducing with nigericin or with valinomycin plus carbonyl cyanide p‐trifluoromethoxy phenylhydrazone (FCCP) electroneutral influx of H+. These exchanges are unaffected by inducing electrogenic efflux of K+ from mitochondria with valinomycin. The malatein‐citrateout exchange appears to be inhibited by electroneutral influx of H+.
Measurement of the extra‐ and intramitochondrial pH shows that the malate‐citrate exchange diffusion is accompanied by translocation of protons, across the mitochondrial membrane, in the same direction as citrate and the Pi‐malate exchange by proton translocation in the direction of malate. Evidence is presented that the proton translocation is a direct consequence of the anion exchange.
It is demonstrated that the H+: citrate and the H+: Pi ratios determined experimentally for the malate‐citrate and malate‐Pi exchanges practically coincide with the theoretical ratios expected for electroneutral malate2‐citrate2‐ and malate2‐HPO:2‐4 exchanges.
The malate‐2‐oxoglutarate exchange is not affected by ionophores and/or uncouplers neither it is accompanied by proton translocation across the mitochondrial membrane.
It is concluded that the malate‐citrate, malate‐Pi and malate‐2‐oxoglutarate exchange diffusion reactions are electroneutral and that the proton translocation accompanying the malate‐citrate and malate‐Pi exchanges is determined by the ionization state of malic, citric and phosphoric acid.
Studies on Lichen Enzymes
Authors: Schultz Joachim , Mosbach Klaus 
Published: March 2005

From the lichen Lasallia pustulata a new enzyme, “orsellinate depside hydrolase”, capable of catalyzing the hydrolysis of certain depsides to corresponding resorcylic acid monomers, has been isolated.The enzyme is extremely substrate‐specific; only depsides based on orsellinic acid (2,4‐di‐hydroxy‐6‐methyl‐benzoic acid) alone are acceptable. Phenyl benzoate and m‐digallic acid are not hydrolysed. Purification of the enzyme 135‐fold has been achieved with a final specific activity of 1300 U/mg of protein. The enzyme has a molecular weight of 42000 as determined by dodecylsulphate‐polyacrylamide gel electrophoresis. Only a single sharp peak was obtained by analytical ultracentrifugation. Electrofocussing of the hydrolase in polyacrylamide gel resolved the protein into four distinct enzymatically‐active bands. A Km of 56 μM has been determined using the depside lecanoric acid as substrate. The enzyme has been shown to be unusually stable to heat. On treatment of the enzyme for 22 h with 5 mM diisopropylfluorophosphate 75% of the activity was lost, typical of a serine esterase.A spectrophotometric method suitable for the assay of orsellinate depside hydrolase is described.
Studies on Deoxyribonucleoprotein Structure
Authors: Ilyin Yurii V. , Varshavsky Alexander Ya. , Mickelsaar Ustav N. , Georgiev Georgii P. 
Published: March 2005

The addition of tRNA to chromatin gel (initial insoluble deoxyribonucleoprotein preparation) in the presence of 1 mM MgCl2 or of 40 mM NaCl results in the transfer of the very lysine‐rich histone (F1) and of some nonhistone proteins to the tRNA, whereas all other histones remain in the deoxyribonucleoprotein. This result provides a new general method for the mild removal of histone F1 from the chromatin gel. The addition of tRNA to chromatin gel in the absence of Mg2+ and Na+ results not only in the rapid removal of histone F1 and of some nonhistone proteins from the chromatin gel, but also in the slow transfer of histones F2a2 and F2b to the tRNA. A similar pattern of histone redistribution is observed when the tRNA (or DNA) is added to the soluble deoxyribonucleoprotein preparation obtained by mechanical disruption of the chromatin gel.
There is no protein redistribution in the above‐mentioned soluble deoxyribonucleoprotein preparation (in the absence of exogeneous free polynucleotides).
The addition of free DNA or tRNA to the soluble deoxyribonucleoprotein preparation, obtained by treatment of the chromatin gel with 2 M urea, allows one to remove quantitatively histones F1, F2a2 and F2b from the deoxyribonucleoprotein, leaving the initial distribution of the arginine‐rich histones (F2a1 and F3) on the endogeneous DNA unchanged.
The redistribution of proteins (and in particular of histones) occurs in the soluble deoxyribonucleoprotein preparation obtained by urea treatment even in the absence of any exogeneous polynucleotides suggesting that conservation of the initial distribution of proteins in this soluble deoxyribonucleoprotein preparation is not complete.
The Purification and Properties of the NAD‐Linked Aldehyde Dehydrogenase from Pig Brain
Authors: Duncan R. Julian S. , Tipton Keith F. 
Published: March 2005

The NAD‐linked aldehyde dehydrogenase from pig brain has been purified some 90‐fold over extracts of acetone powders of whole brain. This preparation of enzyme is unstable, and a less pure, more stable preparation has been used to investigate some of the properties of the enzyme.
Inhibition of the enzyme by the monoamine oxidase inhibitors 2‐phenylethylhydrazine and 2‐phenyl‐1‐methylethylhydrazine is reported.
Ethanol and reserpine have both been found not to inhibit aldehyde dehydrogenase.
On the basis of inhibition by o‐iodosobenzoate and phenylarsenious oxide it is proposed that the enzyme has two juxtaposed sulphydryl groups at or near the active site.
Irreversible inhibition by certain conjugated, unsaturated aldehydes is reported.
Non‐enzymic reactions of NAD+ with indole‐3‐acetaldehyde and phenylacetaldehyde are described. The reaction products are spectrally similar to NADH, but by enzymic criteria are not NADH. It is postulated that the products are the adducts between the aldehydes and the nicotinamide moiety of the coenzyme.
Studies on the Attachment of the Bovine J Blood‐Group Substance at the Erythrocyte Membrane
Authors: Schröffel Jaroslav , Thiele Otto Wolfgang , Koch Johannes 
Published: March 2005

By means of quantitative studies of the J activity of bovine intact erythrocytes and of erythrocyte lipids it is concluded that all of the J activity of J‐containing cells is due to a lipid and that all J substance is present on the erythrocyte surface and thus available for J antibody. No J substance seems to be buried in the depth of the membrane.During the process of hemolysis and subsequent washings bovine erythrocytes release a considerable portion of their membrane constituents in a “soluble” form. In order to prevent a disruption of ghosts a small amount of MgCl2 must be added to the hemolyzing mixture. We observed a loss of more than 30% of the original J activity along with about 15% of various stroma constituents unless MgCl2 had been added to the hemolyzing mixture.By treatment of bovine stroma (prepared in the presence of added MgCl2) with organic solvents of increasing polarity two lipid fractions, “loosely” and “strongly” bound lipids, can be obtained. The J activity was found only in the “strongly” bound fraction along with the majority of glycolipids.By treatment of bovine J‐cell ghosts with hypertonic saline part of the stroma constituents, including the J substance, is solubilized. It is concluded that the J substance, though secondarily absorbed from the serum onto the erythrocyte surface, is fully integrated to the other membrane constituents.
Synthetic Polynucleotides
Authors: Roychoudhury Ranajit , Kössel Hans 
Published: March 2005

The use of chemically synthesized hexathymidylate as primer for terminal deoxynucleotidyl transferase in the presence of a ribonucleoside triphosphate and Mg2+ results in a limited addition of ribonucleotides at the 3′‐end of the primer. The incorporation is absolutely dependent upon the presence of Mg2+ and primer, and the pH optimum is similar to that observed for deoxynucleotide incorporation.
The priming efficiency decreases when oligothymidylates of smaller chain length are used according to the order: hexa > penta > tetra > tri. The incorporation into the trinucleotide is very small.
Depending upon the primer: triphosphate ratio, the reaction mixture after incubation contains either a mono‐ or a diaddition product, or both and such products can be synthesized under controlled conditions. The upper limit of this terminal addition has been found to be up to two nucleotide units. A ribonucleotide to ribonucleotide linkage is formed in the case of the diaddition product.
The ribonucleotide terminated hexathymidylates are capable of accepting dAMP residues from dATP in the presence of terminal deoxynucleotidyl transferase to give rise to a polymeric product whereby the newly synthesized polymer remains covalently linked to the original hexathymidylate by a ribonucleotide linkage.
Due to the presence of this ribonucleotide linkage, the polymeric product can be cleaved from the primer by alkaline hydrolysis, resulting in a separation of the primer sequences from the product sequences. The use of ribonucleotide terminated oligodeoxynucleotides thus provides a valuable tool for enzymic synthesis of polydeoxynucleotides, whereby the material used as primer (necessary for an enzyme catalyzed reaction) can be removed from the product.
Replication of Bacteriophage M13
Authors: Kluge Friedrich , Staudenbauer Walter L. , Hofschneider Peter Hans 
Published: March 2005

After infection of Escherichia coli K12 strains with the single stranded DNA bacteriophage M13, between 85–95% of the intracellular parental DNA molecules are found attached to the host membrane.
This attachment is not irreversible. Even in singly infected cells up to 30% of the membrane bound parental DNA molecules are released from the membrane site and transferred to progeny phages during the first hour of infection.
The turnover of the membrane‐bound parental DNA depends strongly on the host system studied, indicating that this process may reflect primarily a property of the host.
The J Blood‐Group Substance of Cattle
Authors: Schröffel Jaroslav , Radaš Antonín , Thiele Otto Wolfgang , Koch Johannes 
Published: March 2005

In cattle with J blood‐group substance both on erythrocytes and dissolved in serum, J activity was found in the total lipids extracted from erythrocytes, but not in the proteins precipitated by lipid extraction and not in the mucoproteins prepared from erythrocytes. Serum from these animals, however, does not only exhibit J activity of its total lipid, but also of its mucoproteins and of its residue after lipid extraction. This serum, therefore, contains the J substance in at least two different forms, as a lipoprotein and as a mucoprotein. Only the J lipoprotein is able to coat bovine erythrocytes during a postnatal period. It is suggested that hydrophobic groups are responsible for the attachment of the J substance to the erythrocytes.In cattle with J substance only in serum, coating of erythrocytes is missing. This is apparently due to the finding that the serum from these animals contains J mucoproteins, but virtually no J lipoprotein. Since the determinant of the J lipoprotein has been found in the glycosphingolipid fraction the genetically fixed difference between animals which have J substance on erythrocytes and in serum and those which have it only in serum seems to consist in the inability of the latter animals to synthesize a glycosphingolipid containing the sequence of sugars which is responsible for J specificity.