bluuebunny/crossref_metadata_2025_split huggingface dataset:
Steroid‐Induced Early Protein Synthesis in Rat Uterus and Prostate
Authors: PENNEQUIN Pierre , ROBEL Paul , BAULIEU Etienne‐Emile 
Published: March 2005

An early ‘induced protein’, after exposure of the rat uterus to estradiol, is detected among the soluble proteins with a double‐labelling technique and electrophoretic fractionation. Efforts have been directed to establish the subcellular distribution of the induced protein, since such a protein, observable 1 h after hormone administration, may play an important role in the subsequent amplified responses, especially in terms of RNA synthesis. Moreover such an early discrete induced protein was sought in a comparable system responding to another hormone, namely prostate and seminal vesicles under androgens. The induced protein was not found in uterine nuclei of 21‐day‐old rats after 1 h of estradiol action in vivo and 1 h of tissue incubation with labelled leucine. This negative result summarizes a search among different nuclear protein fractions using various procedures; nor was induced protein observed in mitochondrial and microsomal pellets. Contrary to these negative findings, slight changes of histone labelling were observed under the experimental conditions used to demonstrate induced protein. In addition histone acetylation was increased after 1 h of estradiol action in vivo and 15 min tissue labelling in vitro with radioactive acetate.Furthermore, an increase in total protein synthesis between 0 and 2 h after estradiol action was observed, the relative increase of incorporation of radioactive leucine into protein of estradiol‐treated vs non‐stimulated uteri being corrected for variations of the acid‐soluble radioactive leucine pool.Attempts to obtain an early and discrete induced protein with androgens in prostate and seminal vesicles of immature or castrated rats after different times of exposure to testosterone, androstanolone and estradiol have been unsuccessful.The contribution of both negative and positive findings in steroid‐induced early protein synthesis is discussed in the context of the current knowledge of hormone action.
Compartmentation of Acetyl‐CoA in Rat‐Liver Mitochondria
Authors: VON GLUTZ Gaston , WALTER Paul 
Published: March 2005

The ratio of the specific radioactivities of 3‐hydroxybutyrate: citrate was determined in rat liver mitochondria which were incubated in the presence of [1‐14C]palmitate, pyruvate, bicarbonate, ATP, phosphate and' malonate. Without compartmentation this ratio would maximally be 2, however, under our conditions values of 2.5 ‐ 3.7 were observed.In further experiments with mitochondria, the sensitivity of pyruvate carboxylase for acetylCoA produced from various precursors was tested. It was found that acetyl‐CoA produced from L‐acetylcarnitine or by oxidation from either pyruvate, octanoate or palmitylcarnitine but not from leucine led to a stimulation of pyruvate carboxylation.These results demonstrate a compartmentation of acetyl‐CoA in liver mitochondria. The further finding that different mitochondrial fractions showed varying ratios of specific radioactivities of 3‐hydroxybutyrate: citrate indicates that the observed compartmentation may be explained by the existence of different types of mitochondria with varying enzyme patterns and acetyl‐CoA pools
RNA Polymerase B from Drosophila melanogaster Larvae
Authors: GREENLEAF Arno L. , BAUTZ Ekkehard K. F. 
Published: March 2005

A purification procedure is described by which we obtained DNA‐dependent RNA polyrnerase B (or II) from third‐instar larvae of Drosophila melanogaster in essentially pure form. The enzyme is similar to the analogous polymerases from other eukaryotes in its enzymic and structural properties. lt preferentially transcribes DNAs containing single‐stranded regions, and it is inhibited by low amounts of the toxin α‐amanitin; 50 % inhibition occurs at an α‐amanitin concentration of 0.03 μ/m1. Dodecylsulfate‐polyacrylamide gel electrophoresis resolves the purified Drosophila polymerase B into ten polypeptides with molecular weights as follows: 1 (174000), 2 (137000), 3 (34000). 4 (22000). 5 (18000), 6 and 7 (16000), 8 (15000), and 9 and 10 (less than 15000). The relative amounts of polypeptides 1–4 were constant at molar ratlos of approximately 1:1:1:2 in different preparations of the enzyme, while the amounts of polypeptides 5–10 showed more variation.An antiserum directed against the Drosophila RNA polymerase B inhibited the activity in vitro of the B enzymes from Drosophila, yeast, and calf thymus. However, only the Drosophila enzyme gave a precipitin reaction with the antiserum. When the antiserum was added to Drosophila RNA polymerase B at different stages of the purification, the resulting precipitates were found to contain nearly constant proportions of seven of the ten polypeptides present in the purified enzyme
Determination in vitro of the Rate of Protein Synthesis and Degradation in Human‐Skeletal‐Muscle Tissue
Authors: LUNDHOLM Kent , SCHERSTÉN Tore 
Published: March 2005

The present studies were aimed to evaluate the possibility to use a system for estimation in vitro of the biosynthesis and degradation rates of human skeletal muscle protein. A previously characterized human skeletal muscle preparation was used.Amino acids and insulin stimulated significantly the incorporation rate of leucine into proteins. The effect of amino acids was more pronounced than that of insulin. The stimulatory effect of insulin could be decreased by amino acids. Insulin did not influence the tissue uptake or the oxidation rate of leucine.The release of [14C]leucine deriving from degradation of prelabelled skeletal muscle fibre proteins was linear for at least 2.5 h of incubation and optimal with leucine at concentrations beyond 12.5 mmol/1 or in the presence of puromycin in the incubation medium. The rate of the release of radioactivity was significantly inhibited by amino acids and at borderline significance by insulin but not by puromycin. The specific radioactivity in prelabelled proteins decreased significantly in the presence of puromycin suggesting that leucine derived from protein degradation was reutilized in vitro. This reutilization was found to be 9 ± 1 % of leucine released from degradation of proteins in 30 subjects.A statistically significant positive correlation between the cathepsin D activity in human skeletal muscle tissue and the degradative rate of prelabelled muscle proteins in vitro was observed.The results indicate that biosynthesis and degradatiön of skeletal muscle proteins in this system in vitro were subjected to control mechanisms. It is suggested that the release of radioactivity from prelabelled muscle fibre proteins during incubation probably only reflects the degradation of some rapidly‐turning‐over proteins.
Spin‐Labelled Phosphofructokinase
Authors: JONES Robert , DWEK Raymond A. , WALKER Ian O. 
Published: March 2005

Rabbit muscle phosphofructokinase, spin‐Labelled at its most reactive thiol group, has an electron spin resonance spectrum which is very sensitive to the binding of substrates and allosteric effectors. The spectral changes have been interpreted in terms of a concerted allosteric transition between two conformational states with non‐exclusive binding of effectors. Ort this basis MgATP, fructose 6‐phosphate plus ATP, and NH4+ ions behave as potent positive effectors, inorganic phosphate, sulphate, AMP, fructose 6‐phosphate and fructose 1,6‐bisphosphate are less potent activators, and free ATP and H+ ions are negative effectors, in agreement with the kinetic behaviour, but citrate behaves anomalously. In addition, the allosteric equilibrium can be displaced towards the inhibited state by selectively modifying two further thiol groups.Strong positive cooperativity occurs under suitable conditions with ATP, metal‐ATP and fructose 6‐phosphate. Biphasic changes of conformation, attributed to binding at the catalytic and inhibitory sites, have been observed in titrations with ATP. The differentiation of the two ATP binding sites arises in the presence of fructose 6‐phosphate because of a distinct concerted effect an conformation between the two substrates at the active site. A similar effect occurs between ATP and citrate. Other heterotropic effects are more consistent with simple modelst phosphates favour the binding, and reduce the cooperativity, of fructose 6‐phosphate and metal‐ATP, whereas excess ATP and H+ ions antagonise the binding and increase the cooperativity of fructose 6‐phosphate.The observations are related to existing kinetic and binding studies where possible. Anomalous features of the behaviour suggest that the model should be regarded only as a first approximation
Ribosome Inactivation by the Toxic Lectins Abrin and Ricin
Authors: OLSNES Sjur , FERNANDEZ‐PUENTES Carmen , CARRASCO Luis , VAZQUEZ David 
Published: March 2005

A sensitive test system for toxin‐treated ribosomes was worked out by treating rabbit reticulocyte ribosomes with abrin A‐chain, ricin A‐chain or ricinus agglutinin A‐chain, adding neutralizing amounts of specific antitoxins and testing for polyphenylalanine‐synthesizing activity in a system where the concentration of elongation factors and ribosomes were varied. The strongest inhibition was obtained in the presence of low concentrations of elongation factor 2 (EF‐2).The activity of the ribosomes decreased with time of incubation with the toxin A‐chains. Addition of anti‐toxins stopped further inactivation. In systems containing untreated and toxin‐treated ribosomes the ability to polymerize phenylalanine was proportional to the concentration of untreated ribosomes.There was a linear relationship between toxin A‐chain concentration and the number of ribosomes inactivated per minute. The inactivation rate increased with temperature, and the estimated activation energy was 10.6 kcal (44.3 kJ). Linewaver‐Burk plots of the data obtained by incubating various ribosome concentrations with toxins indicated a molecular activity of about 1500 ribosomes/minute for abrin and ricin A‐chains and 100 ribosomes/minute for ricinus agglutinin A‐chain. The apparent Michaelis constant was 0.1‐0.2 μM for all three A‐chains. The activity of the A‐chains in the intact cell is discussed.
The First Enzyme of the gal Operon in Inducible and Operator‐Constitutive Strains of Escherichia coli
Authors: DEELEY Roger , BLACKBURN Peter , FERDINAND William , BRIDGEN John 
Published: March 2005

UDPgalactose 4‐epimerase, the product of the first structural gene of the gal operon in Escherichia coli K‐12, has been purified from strain HfrH and from its gal operator‐constitutive mutant, HfrH 81‐2.
The two enzymes are purified by the same procedure, behaving identically throughout. They are identical in sedimentation coefficient, isoelectric point, electrophoretic mobility at pH 8.8 and amino‐terminal sequence for the first 30 residues.
Slight but reproducible differences were observed between the amino acid compositions and peptide maps of the two proteins. These differences may indicate real differences in the primary sequences of the proteins, but if so they are unlikely to be due to the operator‐constitutive mutation because of the identity of the sequences for the first 30 residues.
No evidence was found to indicate that the gal operator might overlap with the first structural gene.
Radioimmunoassay for Human and Chick Prolyl Hydroxylases
Authors: TUDERMAN Leena , KUUTTI Eeva‐Riitta , KIVIRIKKO Kari I. 
Published: March 2005

A radioimmunoassay is reported for measuring prolyl hydroxylase. The assay is based on the displacement of radioactively‐labelled prolyl hydroxylase from its antibody by the non‐labelled enzyme, and on the subsequent precipitation of the enzyme‐antibody complex by a cellulose‐bound second antibody. Pure prolyl hydroxylase was isolated from foetal human or chick embryo tissues by an affinity column procedure using poly(l‐proline). The enzyme was labelled with tritium using a technique of reductive alkylation with formaldehyde and sodium [3H]borohydride. No conversion of the enzyme tetramer to its monomers was found to take place during the tritiation reaction. Experiments on the dissociation of the non‐labelled enzyme indicated that the degree of displacement of the labelled enzyme was similar regardless of whether the non‐labelled enzyme was in the tetramer form or in that of the subunit monomers.The sensitivity of the radioimmunoassay is of the order of 5‐10 ng immunoreactive prolyl hydroxylase. The concentrations of the immunoreactive prolyl hydroxylase assayed with the present method in human serum and skin and in several chick embryo tissues are reported.
On the Control of Arginine Metabolism in Chicken Kidney and Liver
Authors: GRAZI Enrico , MAGRI Ermes , BALBONI Giancarlo 
Published: March 2005

Arginases have been found to be located on the external side of the inner mitochondrial membrane of chicken kidney and liver.Transamidinase has been detected within the liver mitochondrial matrix space.Arginases and transamidinase act upon two different intracellular arginine pools.Penetration of arginine into the matrix space occurs only in respiring mitochondria and in the presence of anions such as acetate and phosphate; d‐arginine, l‐ornithine, d‐ornithine and l‐lysine penetrate with the same modalities. l‐Histidine penetrates only kidney mitochondria.Because of transamidinase compartmentation, the rate of creatine synthesis is influenced by the rate of penetration of arginine into the mitochondria.
Properties of the Ribose‐Ring‐Opened Adenine Nucleotide, 2,2′[1‐(9‐adenyl)‐1′‐(tri‐,diphosphoryl‐oxymethyl)]‐dihydroxydiethylether in Mitochondrial Adenine‐Nucleotide Translocation
Authors: BOOS Karl Siegfried , SCHLIMME Eckhard , BOJANOVSKI Dubo , LAMPRECHT Walther 
Published: March 2005

(Adenine‐14C) or (γ‐32P)‐labelled 2,2′(1‐(9‐adenyl)‐1′‐(tri‐, diphosphoryl‐oxymethyl)]‐dihydroxydiethylether (rroANP) was obtained from ANP by cleavage of the C‐2′‐C‐3′ bond by sodium periodate oxidation and subsequent borohydride reduction.Binding of rroANP to rat liver mitochondria revealed carrier‐linked (atractyloside‐sensitive) and unspecific (atractyloside‐insensitive) binding but no transfer across the inner mitochondrial membrane. Kinetic data indicate rroANP as a competitive inhibitor for ANP uptake with Ki=9.3 × 10−5M. Experimental rroANP confirmed that an intact adenine base and three anionic charges of the phosphate chain are essential for the recognition between ANP‐carrier and nucleotide but insufficient for the induction of a transmembrane ANP exchange. In addition mobilisation of the carrier‐nucleotide complex requires an intact ribofuranoside ring system.
DNA Polymerases of Rat Liver
Authors: ZUNINO Franco , GAMBETTA Romolo , COLOMBO Ambrogio , LUONI Giuseppe , ZACCARA Adriano 
Published: March 2005

Three distinct DNA‐dependent DNA polymerase activitives have been partially purified from normal rat liver. Soluble activities are separable into two distinct fractions (P1 and P2) by phosphocellulose chromatography. A low‐molecular‐weight DNA polymerase was isolated from purified nuclei. The enzymes were characterized according to chromatographic and sedimentation behavior, enzymological properties, and response to various inhibitors. The results indicate that fraction P1 corresponds to the high‐molecular‐weight enzyme and suggest that polymerase P2 may be derived from partial dissociation of the high‐molecular‐weight enzyme. The molecular weight of polymerase P1 was estimated to be about 250000 by Sephadex column chromatography. Both fraction P2 and nuclear DNA polymerase appeared to be low‐molecular‐weight enzymes. However, the molecular size of these activities was apparently different. The estimated molecular weights of nuclear and P2 enzyme are about 40000 and 25000, respectively.As with the nuclear enzyme, polymerase P2 (but not P1) appeared to be free of detectable exonuclease activity. All of these polymerases showed a marked preference for initiated polydeoxyribonucleotide templates. The rat liver polymerases differed in their ability to use poly[d(A‐T)] primer‐template, as is shown by the ratios of their activity with this synthetic polymer to that with activated DNA: 0.5, 2.75, and 1.34 for P1, P2, and nuclear polymerase, respectively. Denatured DNA was a poor template for both enzymes P1 and P2, but it was inert as template for the nuclear enzyme.Although each of these polymerases required all four deoxynucleoside triphosphates for maximal activity, they catalyzed a high rate of synthesis in the absence of one or more deoxynucleoside triphosphates. Such a ‘limited’ synthesis was much more extensive for polymerase P2 and nuclear enzyme than for P1. Polymerase P1 was the most sensitive of the three to sulphydryl reagents, ethidium bromide, heparin, and single‐stranded DNA. The responses of P2 and nuclear enzymes to various inhibitors were very similar. However, these two enzymes respond differently to heat and high ionic strength.
Luminescence Studies of Saccharide Binding to Wheat Germ Agglutinin (Lectin)
Authors: PRIVAT Jean‐Paul , MONSIGNY Michel 
Published: March 2005

The fluorescence and phosphorescence emission of wheat germ agglutinin are reported.Fluorescent tryptophan residues of wheat germ agglutinin are found highly exposed to solvent: fluorescence quenching induced by temperature fits with a single Arrhenius critical energy close to that of tryptophan in solution; the whole fluorescence emission is susceptible to iodide ion quenching and data reveal the homogeneity of fluorescence arising from only one type of tryptophan exposition.Energy transfers are analyzed at singlet and triplet state level. Tyrosine fluorescence at 25 °C is very weak. Results obtained from the relative excitation fluorescence quantum yield and from intrinsic fluorescence polarization show that a large amount of energy absorbed by tyrosine at 280 nm is transferred to tryptophan residues. However, tyrosine fluorescence is highly increased at 70 °C although disulfide bridges are not reduced. The phosphorescence spectrum at 77 K in 50%, ethylene glycol is finely structured with several resolved vibrational bands at 405, 432 and 455 nm. Phos‐phorescence decay can be fitted with a single exponential. Lifetime is independent of excitation wave‐length. Its value is very close to that of free tryptophan.Influence of tri‐N‐acetyl‐chitotriose binding on luminescence properties are investigated. Results are analyzed in terms of steric tryptophan‐ligand relationships. It is shown that all the fluorescent chromophores are concerned by the ligand binding but all fluorescence emission is still susceptible to iodide ion quenching. There is no change induced in energy transfer at the singlet state level and no modification in triplet state population.
A Contribution of Nonhistone Proteins to the Conformation of Chromatin
Authors: TASHIRO Tomoko , KUROKAWA Masanori 
Published: March 2005

Changes in circular dichroism (CD) spectra and thermal melting profiles of guinea pig liver DNA reassociated with histones and/or nonhistone proteins from the cerebral or liver chromatin are described.
In the DNA · histone complex, positive ellipticity in the CD spectrum at 260–300 nm is progressively lowered as the histone/DNA ratio is increased; this is accompanied by a red‐shift of the crossover point at around 260 nm. DNA in this complex is thermally stabilised to a considerable extent, but not to such a full extent as is shown with DNA in native chromatin.
DNA · nonhistone complex in 0.14 M NaCl is, in contrast to DNA · histone complex, not precipitable by centrifugation at 20000 × g. DNA in this complex shows only a slight reduction in ellipticity at 260–300 nm, and a very weak thermal stabilisation.
Characteristics in the CD spectrum of the native chromatin are most satisfactorily reproduced in the DNA · histone · nonhistone complex. These include a large decrease in ellipticity at 260–300 nm, a red‐shift of the crossover point at around 260 nm, and a slight negative band at around 305 nm. Also, DNA in this complex is thermally stabilised to the extent comparable with DNA in the native chromatin.
Addition of nonhistone proteins to the preformed DNA · histone complex in 3 M urea renders a half of the complex, named DNA · histone(· nonhistone), unprecipitable upon centrifugation at 20000 ×g in 0.14 M NaCl. CD spectrum and thermal melting profile of the precipitable DNA · histone(·nonhistone) complex are similar to those of the DNA · histone · nonhistone complex, while in the unprecipitable DNA · histone(· nonhistone) complex, the ellipticity at 260 – 300 nm is significantly elevated and the highest melting transition (at 80 °C) is lacking.
The CD spectrum of native cerebral chromatin closely resembles that of unprecipitable DNA · histone(·nonhistone) complex, while in liver chromatin, the spectrum is an intermediate between those of the unprecipitable and precipitable complexes, suggesting an organ‐specific modification of chromatin by nonhistone proteins. Cerebral nonhistone proteins bind to DNA and to the DNA · histone complex more extensively than liver nonhistone proteins.
It is concluded that, although the basic conformation of DNA in native chromatin is determined largely by histones, nonhistone proteins also play an individual role. There is also an indication that nonhistone proteins exert an organ‐specific modification of chromatin superstructure.
Structure and Synthesis of a Lipid‐Containing Bacteriophage
Authors: TSUKAGOSHI Norihiro , PETERSEN Marianne H. , FRANKLIN Richard M. 
Published: March 2005

Enzymes of glycerophosphatide biosynthesis and degradation have been characterized using membrane fractions of Pseudomonas BAL‐31, the host cell of the lipid‐containing bacteriophage PM2. Inner and outer membrane fractions were investigated. Whereas the outer membrane con‐tained more phosphatidylethanolamine and less phosphatidylglycerol than the inner membrane, the fatty acid composition was almost the same for both membranes. The pathway for glycerophos‐phatide biosynthesis was the same as that for Escherichia coli and Bacillus megaterium. The biosyn‐thesis of phosphatidylserine and phosphatidylglycerol was shown to proceed via CDP‐diglyceride as a common intermediate. Phospholipase A hydrolyzed phosphatidylethanolamine more efficiently than phosphatidylglycerol. All of the enzymatic activities were stimulated by Triton X‐100. Phos‐phatidylserine synthetase was stimulated by Na2SO4 and inhibited by Mg2+. Phosphatidylserine decarboxylase was completely inhibited by NH2OH. Phosphatidylglyceror synthetase was stimulated by Mg2+. Phospholipase A was stimulated by Ca2+. Phosphatidylserine decarboxylase and phosphatidylglycerol synthetase were localized in the inner membrane fraction. Phosphatidylserine synthetase and phospholipase A were found in both outer and inner membrane fractions.Effects of virus infection on these enzymes were studied. Phosphatidylglycerol synthetase and phospholipase A activity against phosphatidylethanolamine were activated early post‐infection. Phosphatidylserine synthetase and decarboxylase remained unaltered. At later times post‐infection, phosphatidylglycerol synthetase and phosphatidylserine decarboxylase were inactivated and phos‐ phatidylserine synthetase was activated. There was little alteration in phospholipase A activity against phosphatidylglycerol after infection.