bluuebunny/crossref_metadata_2025_split huggingface dataset:
Mitochondrial Heredity of Resistance to 3‐(3,4‐Dichlorophenyl)‐1,1‐dimethylurea, an Inhibitor of Cytochrome b Oxidation, in Saccharomyces cerevisiae
Authors: COLSON Anne‐Marie , THE VAN Luu , CONVENT Bernard , BRIQUET Michel , GOFFEAU André 
Published: March 2005

3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (diuron), an inhibitor of cytochrome b oxidation, has been used for the selection of three resistant mutants, (diur) of Saccharomyces cerevisiae. The mutant diur‐64 exhibits in vivo cross‐resistance to antimycin A while diur‐34 and diur‐1 are more sensitive to antimycin A than the parental strain. The three mutants exhibit mitochondrial inheritance according to the following criteria: mitotic segregation of diuron‐resistant and diuron‐sensitive diploids is obtained among the diploid progeny of a cross between diur and dius; non‐Mendelian segregation of diuron resistance (4:0) is observed in spores of tetrads issued from diuron‐resistant diploid; extensive ethidium bromide treatment leads to the formation of Q– mutants which no longer transmit diur and dius alleles.Evidence for two distinct diuron‐resistant loci were obtained by allelism tests. Recombination analysis shows that diuron‐resistance is not located in the polar region of the mitochondrial genome. The diur loci are not linked to the erythromycin locus since the upper limit in recombinants frequency (26%) for a non‐polar region is obtained between diur and eryr. A low recombinants frequency (3%) is observed in crosses between diur‐34 mutation and the two mutants cob1 and cob2 suggesting that diur‐34 might be located between these two cytochrome‐b‐deficient loci.The resistance to diuron is also expressed in vitro since the oxidation rates of succinate by sonicated submitochondrial particles from the mutants are clearly less sensitive to diuron than that of the wild type.
Complexity of the Structure of Particles Containing Heterogeneous Nuclear RNA as Demonstrated by Ribonuclease Treatment
Authors: STEVENIN James , GALLINARO‐MATRINGE Héléne , GATTONI Renata , JACOB Monique 
Published: March 2005

Brain ribonucleoprotein particles containing heterogeneous nuclear RNA (hnRNA) and a large number of polypeptides ranging from 23000 to 150000 molecular weight were treated with pancreatic and T1 ribonucleases at low (0.1 or 0.5 μg plus 5 or 25 units/ml), high (2 μg plus 100 units/ml) and very high (20 μg plus 1000 units/ml) concentrations.At low enzyme concentration, a large fraction of the particle material accumulated at 35–45 S. The accumulation was more marked for proteins in the 30000–38000 molecular weight range. Heterogeneous complexes containing a large spectrum of proteins with a characteristic distribution were disclosed between 60 and 200 S. At high ribonuclease concentration the total quantity of proteins at 35–45 S decreased, but the proteins of 30000–38000 molecular weight predominated. Heterogeneous complexes were also present. Finally, at very high enzyme concentration, the particles were almost entirely hydrolyzed. Only a small amount of heterogeneous complexes subsisted at 30–190 S.The RNA content of the remaining ribonucleoprotein complexes as well as its size decreased upon ribonuclease treatment as shown by CsCl density determination and electrophoretic analysis. The results suggested that the stability of the complexes depended upon protein‐protein as well as RNA‐protein interactions. They also showed that sequences up to 200–300 nucleotides were protected by proteins against ribonuclease.The results were compatible with the existence of at least 3 constituents in the particles. The previously defined monoparticle population accumulating at 35–45 S was heterogeneous in respect to ribonuclease sensitivity and protein composition. The 30000–38000 molecular weight proteins accumulating at low ribonuclease and predominating afterwards were assumed to belong to monoparticles α. Monoparticles β contained a larger range of proteins more easily released by the enzymes. The heterogeneous complexes were a third constituent whose relationship with the monoparticles war not established yet. A large fraction of the particle phosphoproteins was associated to these complexes.On the basis of our experiments in vitro it is assumed that monoparticle α can be preferentially isolated from the nuclei under conditions where endogeneous ribonuclease is high and (or) not inhibited. This might explain why, in certain cases, only one or a few proteins were described in nuclear particles instead of the complete set present in the native particles.
Purification and Characterization of Human Hypoxanthine/Guanine Phosphoribosyltransferase
Authors: MUENSCH Helmut , YOSHIDA Akira 
Published: March 2005

Human hypoxanthine/guanine phosphoribosyltransferase (EC 2.4.2.8) was purified from red blood cells by the following two methods. Method A includes (a) elimination of hemoglobin by DEAE‐cellulose, (b) DEAE‐Sephadex chromatography, (c) specific elution of the enzyme from CM‐Sephadex by pyrophosphate and (d) Sephadex G‐100 gel filtration. Method B includes (a) elimination of hemoglobin by DEAE‐cellulose, (b) acid treatment at pH 4.5, (c) ammonium sulfate fractionation, (d) DEAE‐Sephadex chromatography, (e) heat treatment at 85°C and (f) Sephadex G‐100 gel filtration.Homogeneous enzyme preparation was obtained by the two methods with 8000–9000‐fold purification. The sedimentation coefficient (s20, w) was 5.5–5.6 S, and the molecular weight of the enzyme was estimated at about 85000 by the sedimentation equilibrium method. The subunit molecular weight of the untreated protein and S‐carboxymethylmaleyl protein was estimated as 41000–45000 by the sedimentation equilibrium method in the presence of guanidine hydrochloride. However, the subunit size estimated by the sodium dodecylsulfate gel electrophoresis was only 26000. Amino acid composition of the enzyme was determined. Glucosamine, sialic acid and hexose were not detected in the enzyme.
Characterization of a Protein Factor Stimulating RNA Synthesis by DNA‐Dependent RNA Polymerase II from Plant Cell Cultures
Authors: LINK Gerhard , RICHTER Gerhard 
Published: March 2005

During purification of DNA‐dependent RNA polymerase II (or B) from cell cultures of parsley a protein fraction was separated by phosphocellulose chromatography which enhanced RNA synthesis in the presence of native homologous DNA. This ‘stimulatory factor’ was characterized in respect to some effects on the reaction catalyzed by RNA polymerase II. In the presence of the factor the metal ion requirements as well as the ionic strength for optimal RNA synthesis were markedly changed; addition of the factor to RNA polymerase II purified by cellulose chromatography restored those enzyme properties which had apparently changed upon this purification step. The chain length of the RNA product synthesized is favouring the view that the factor acts mainly by stabilizing the elongation step during transcription.The stimulatory factor was further purified by several steps of column chromatography. As derived from the results of gel electrophoresis under denaturing conditions the factor consists of several small polypeptides. Those of Mr= 26000, 25000 and 14000 apparently have counterparts among the smaller subunits of highly purified RNA polymerase II from parsley cells. Another polypeptide of the factor, with Mr= 30000, was only found in those preparations of RNA polymerase II which had not been subjected to phosphocellulose chromatography.
Increased de Novo Pyrimidine Nucleotide Synthesis in Liver Induced by Ammonium Ions in Amounts Surpassing the Urea Cycle Capacity
Authors: PAUSCH Jürgen G. , GEROK Wolfgang , KEPPLER Dietrich O. R. 
Published: March 2005

An increased rate of de novo pyrimidine nucleotide synthesis is induced in rat liver by administration of ammonium ions. Specific enzymatic analyses demonstrate a marked elevation of the hepatic contents of orotate, UTP, UDP‐glucose, total uracil and cytosine 5′‐nucleotides. Inhibition of uridylate formation by means of 6‐azauridine suppresses the effect of ammonium ions on uracil nucleotide contents and intensifies the accumulation of orotate. After administration of ammonium ions, de novo uridylate synthesis continues at an elevated rate when the hepatic contents of ammonium ions have returned to the normal range. A mediating role of the elevated glutamine levels in the in‐ crease of pyrimidine synthesis induced by ammonium ions has been excluded by an inhibition of glutamine synthetase by methionine sulfoximine.The following evidence indicates that mitochondrial carbamoyl phosphate synthesis from ammonium ions serves as the source of the excess carbamoyl phosphate channeled into cytoplasmic pyrimidine synthesis and leading to an increased formation of orotate and uridylate: (a) acceleration of mitochondrial carbamoyl phosphate consumption by ornithine in the urea cycle prevents the increase of pyrimidine synthesis induced by ammonium ions; (b) inhibition of ornithine carbamoyltransferase by the ornithine analogs norvaline and 2,4‐diaminobutyrate mimics the effect of excess ammonium ions and leads‐to an increased formation of pyrimidines; (c) ascites hepatoma cells deficient in mitochondrial ammonia‐dependent carbamoyl‐phosphate synthetase are unable to increase their rate of pyrimidine synthesis in the presence of ammonium ions.Ornithine has no inhibitory effect on the elevated rate of pyrimidine synthesis elicited by UTP deficiency. This indicates that an efflux of mitochondrial carbamoyl phosphate plays a negligible role in the absence of excess ammonium ions in intact liver. Surplus ammonium ions, however, lead to a state of increased de novo pyrimidine nucleotide synthesis in which the feedback regulation of this pathway by UTP is bypassed.
A Comparative Analysis of the Protein Components of Plasma Membranes Isolated from Differentiated and Undifferentiated Mouse Neuroblastoma Cells in Tissue Culture
Authors: GARVICAN John H. , BROWN Geoffrey L. 
Published: March 2005

The plasma membranes of the cells of mouse neuroblastoma clone NB41A, were isolated without fixation by hardening procedures and were characterised by their enzyme activities and by their morphology in the light and electron microscopes. The membranes were prepared from two kinds of differentiated monolayer cultures; one in which the cells were induced to form long axon‐like processes by the addition of N6,O2′‐dibutyryladenosine 3′:5′‐monophosphate to the culture medium, and the other in which the cells were induced to form processes by the addition of 5‐bromo‐2′‐deoxyuridine. The proteins from the solubilised membranes were compared with similar preparations from the membranes of undifferentiated cells, grown in suspension, by sodium dodecylsulphate polyacrylamide gel electrophoresis, using the incorporation of radioactive amino acids and l‐fucose into proteins in the cultures to follow the differences in the patterns of polypeptide synthesis and glycosylation of the membrane proteins.The differentiated cells induced with either inducer show an increased incorporation of l‐fucose into two distinct components with molecular weights of 60000 and 70000. The two types of induced cells differ from each other in that N6,O2′‐dibutyryladenosine 3′:5′‐monophosphate stimulates both glycosylation and protein synthesis, with a relative increase in the low molecular weight proteins, but 5‐bromo‐2′‐deoxyuridine stimulates mostly increased glycosylation of the membrane proteins.
Involvement of the cytoplasmic membrane in nitrogen fixation by azotobacter vinelandii
Authors: HAAKER Huub , VEEGER Cees 
Published: March 2005

1. Azotobacter vinelandii cells were ruptured by using a French pressure cell, by lysozyme treatment, or by osmotic shock. The rates of sedimentation of nitrogenase from these extracts were compared and related to the rates of sedimentation of marker enzymes. No evidence was found for the so‐called particulate nitrogenase or an interaction between nitrogenase and cytoplasmic membrane vesicles. Nitrogenase sediments as a complex and the rate of sedimentation is comparable with that of pyruvate dehydrogenase complex.2. The oxygen stability of nitrogenase from Azotobacter is not caused by the presence of cytoplasmic membranes in extracts but by a complexation of the nitrogenase components with an Fe‐S protein. Recombination experiments showed that maximum stabilization against oxygen was only obtained at certain ratios of the Fe‐S‐protein and nitrogenase complex. It is proposed that the switch‐off state in Azotobacter cells is caused by the oxidation of flavodoxin hydroquinone rather than by a reversible inactivation of the nitrogenase.3. A membrane‐bound NAD(P)H‐flavodoxin oxidoreductase was detected. Evidence was obtained that flavodoxin might also be membrane‐bound.4. A proposal is given for electron donation to nitrogenase in Azotobacter. In this proposal the generation of reducing equivalents for nitrogenase is localized in the cytoplasmic membrane and mediated by the NADH‐flavodoxin oxidoreductase. The pH gradient which is generated by membrane energization, is used to reduce flavodoxin to its hydroquinone form in order to achieve a redox potential low enough to reduce nitrogenase.
Purification of Aldolase C from Rat Brain and Hepatoma
Authors: HATZFELD Antoinette , ELION Jacques , MENNECIER Francois , SCHAPIRA Fanny 
Published: March 2005

An isolation procedure for rat brain aldolase C has been developed which also permits the isolation of aldolase C from experimental hepatomas.Certain enzymatic properties (specific activity and Michaelis constant towards the two specific substrates: fructose 1,6‐bisphosphate and fructose 1‐phosphate) and physico‐chemical properties (molecular weight, N‐terminal amino‐acid) of the two enzymes have been studied and compared. Moreover, an amino‐acid analysis has been carried out for rat brain aldolase C.Within experimental errors, the two enzymes appear to be identical.
Dimerization of Papain Induced by Mercuric Chloride and a Bifunctional Organic Mercurial
Authors: SLUYTERMAN Lamoraal A. AE. , WIJDENES Jacob , VOORN Gysbertus 
Published: March 2005

The bifunctional mercurial meso‐1,4‐bis(acetatomercuri)‐2,3‐diethoxybutane and mercuric chloride are capable of dimerizing papain, by the attachment of the thiol group of two molecules of papain to each molecule of reagent. This is evident from the titration data, gel filtration and sedimentation equilibrium.The conformational change of papain necessary for this reaction is discussed.
Antigenicity of Bovine Ribonuclease Modified at Tyrosine or Arginine Residues
Authors: VAN DER ZEE Ruurd , JAN DUISTERWINKEL Feitse , WELLING Gjalt W. 
Published: March 2005

Bovine pancreatic ribonuclease was treated with tetranitromethane at a molar excess of 100 mol/mol protein at pH 8.0.Spectral studies showed that the nitration reaction can be better quantitated from the absorbance at 381 nm than from the generally used absorbance at 428 nm.With analytical isoelectric focusing it was found that the reaction product contained various derivatives, nitrated to a different extent.The two derivatives with the highest pI value were isolated by preparative isoelectric focusing in layers of granulated gel. Following performic acid oxidation, modified ribonuclease was digested successively with chymotrypsin and thermolysin. Amino acid analyses of the nitrated peptides showed that tyrosine‐115 was nitrated in the component with the highest pI value, while tyrosines‐76 and 115 were modified in the other nitrated component. The latter derivative exhibited the same enzymatic activity and antigenicity as unmodified ribonuclease.Bovine pancreatic ribonuclease was also modified with 1,2‐cyclohexanedione. After ion‐exchange chromatography and tryptic digestion of the oxidized protein it was determined that arginine residues 39 and 85 were modified for more than 90%, while arginine residue 10 was modified for 30%. Arginine residue 33 remained unchanged. The enzymatic activity of the cyclohexanedione‐treated ribonuclease was less than that of the unmodified protein and there was no loss of antigenic reactivity.It was concluded that tyrosine residues 76 and 115, and arginine residues 39 and 85 do not belong to antigenically relevant regions of bovine pancreatic ribonuclease.
Size Distribution of Rat Liver Nuclear RNA Containing mRNA Sequences
Authors: SIPPEL Albrecht E. , GRONER Bernd , HYNES Nancy , SCHÜTZ Günther 
Published: March 2005

Total rat liver poly(A)‐containing polysomal mRNA was size‐fractionated on polyacrylamide gels in 98% formamide. Complementary DNA (cDNA) was prepared from the 8–14‐S mRNA fraction and separated into sequences representing abundant and non‐abundant mRNAs. The cDNA complementary to the abundant small mRNA of the rat liver cell (approximately 20 species) was hybridized to nuclear RNA of different lengths to determine the size distribution of nuclear RNA molecules which contain these messenger sequences. It was found that:1. All abundant 8–14‐S poly(A)‐containing mRNAs have larger nuclear precursor molecules; 20% of the different messenger sequences are found in nuclear RNA of several times their cytoplasmic length.2. 70% of the mass of the examined nuclear messenger sequences is in RNA molecules of a size similar to their polysomal mRNA; 30% are in larger than 18‐S RNA and 2% are between 37 S and 44 S.3. The majority of small messenger‐containing RNA molecules in the RNA prepared from isolated nuclei are of true nuclear origin, since their frequency distribution differs significantly from that of the polysomal 8–14‐S mRNA.
Ca2+‐Dependent Allosteric Regulation of Nicotinamide Nucleotide Transhydrogenase from Pseudomonas aeruginosa
Authors: HÖJEBERG Bo , RYDSTRÖM Jan 
Published: March 2005

1. The addition of Ca2+ to purified nicotinamide nucleotide transhydrogenase from Pseudomonas aeruginosa results in a 2–8‐fold increase in flavin fluorescence, closely resembling that induced by 2′‐AMP (adenosine 2′‐monophosphate). The response to Ca2+ is sigmoidal, with a Hill‐coefficient of 2.6. Reduction of thionicotinamide adenine dinucleotide (oxidised form) by NADH responds in a similar fashion to Ca2+ and 2′‐AMP.2. Mg2+ inhibits the Ca2+‐dependent activation in a competitive fashion, whereas no effect of Mg2+ is observed when the enzyme is activated with 2′‐AMP.3. The pH dependencies of the activations by 2′‐AMP and Ca2+ are different. The activation by Ca2+ shows little or no dependence on pH, whereas higher concentrations of 2′‐AMP are required to obtain the same activation when the pH is increased.4. The addition of both Ca2+ and 2′‐AMP causes a dramatic decrease in the concentration of Ca2+ required for half‐maximal stimulation.5. A negative cooperative effect of NADP+ has been demonstrated indirectly, i.e. addition of NADP+ increases the concentration of Ca2+ required for half‐maximal stimulation.6. These results are interpreted as indicating the existence of separate allosteric binding sites for Ca2+ and 2′‐AMP. Furthermore, Ca2+ is proposed to act as a heterotropic ligand. The results are discussed in terms of current allosteric models.
Thyroglobulin Messenger Ribonucleic Acid Translation in vitro
Authors: CHEBATH Judith , CHABAUD Odile , CARTOUZOU Guy , LISSITZKY Serge , BEČAREVIČ Aleksander 
Published: March 2005

Total polysomes were obtained by homogenization of sheep thyroid glands in Tris‐Cl‐buffered sucrose, pH 7.5, treatment with 2% Triton X‐100 and centrifugation of the magnesium‐treated 27000 ×g supernatant through 1 M sucrose. Purification of thyroglobulin‐specific polysomes was performed by indirect immunoprecipitation with rabbit antibodies to sheep thyroglobulin and donkey antibodies to rabbit immunoglobulin G. Thyroglobulin polysomes represented 30% of total polysomes. Synthesis of thyroglobulin peptides in a reticulocyte cell‐free system, programmed with total RNA from immunoprecipitated polysomes, was 3 times higher than when total RNA from unfractionated polysomes was used. The size of the poly(A)‐containing thyroglobulin mRNA was estimated by the capacity of RNA fractions obtained by sucrose density gradient centrifugation of total or immunopurified polysomal RNA to hybridize with 3H‐labeled poly(U) and to stimulate thyroglobulin peptide synthesis in a reticulocyte lysate. 65% of the thyroglobulin messenger activity was located in a 33–36‐S RNA peak and 35% in zones corresponding to 30‐S and 26‐S RNA species.The thyroglobulin‐specific immunoprecipitable peptides synthesized in the reticulocyte lysate from the 33–36‐S RNA were shown by polyacrylamide gel electrophoresis in denaturing conditions to contain a major component co‐migrating with the constituent peptide chain of sheep thyroglobulin (Mr 330000). Other components migrated with Mr of about 210000 and 120000.
The Complete Amino‐Acid Sequence of Histone H2B(1) from Sperm of the Sea Urchin Parechinus angulosus
Authors: STRICKLAND Marie , STRICKLAND Walter N. , BRANDT Wolf F. , VON HOLT Claus 
Published: March 2005

Two histones have been isolated and purified from sperm cells of the sea urchin Parechinus angulosus. They have been designated sperm histone H2B(1) Parechinus and sperm histone H2B(2) Parechinus on criteria of solubility and partial sequence homology with H2Bcalf.H2B(1) consists of a polypeptide chain of the following 144 amino acid residues: Pro‐Ser‐Gln‐Lys‐Ser‐Pro‐Thr‐Lys‐Arg‐Ser‐Pro‐Thr‐Lys‐Arg‐Ser‐Pro‐Thr‐Lys‐Arg‐Ser‐Pro‐Gln‐Lys‐Gly‐Gly‐Lys‐Gly‐Gly‐Lys‐Gly‐Ala‐Lys‐Arg‐Gly‐Gly‐Lys‐Ala‐Gly‐Lys‐Arg‐Arg‐Arg‐Gly‐Val‐Gln‐Val‐Lys‐Arg‐Arg‐Arg‐Arg‐Arg‐Arg‐Glu‐Ser‐Tyr‐Gly‐Ile‐Tyr‐Ile‐Tyr‐Lys‐Val‐Leu‐Lys‐Gln‐Val‐His‐Pro‐Asp‐Thr‐Gly‐Ile‐Ser‐Ser‐Arg‐Ala‐Met‐Ser‐Val‐Met‐Asn‐Ser‐Phe‐Val‐Asn‐Asp‐Val‐Phe‐Glu‐Arg‐Ile‐Ala‐Ala‐Glu‐Ala‐Gly‐Arg‐Leu‐Thr‐Thr‐Tyr‐Asn‐Arg‐Arg‐Ser‐Thr‐Val‐Ser‐Ser‐Arg‐Glu‐Val‐Gln‐Thr‐Ala‐Val‐Arg‐Leu‐Leu‐Leu‐Pro‐Gly‐Glu‐Leu‐Ala‐Lys‐His‐Ala‐Val‐Ser‐Glu‐Gly‐Thr‐Lys‐Ala‐Val‐Thr‐Lys‐Tyr‐Thr‐Thr‐Ser‐Arg. In a previously published partial sequence serine was incorrectly assigned to position 30.A comparison of the carboxyl‐terminal two thirds of H2B(1) Parechinus and H2Bcalf reveals that 79% of the corresponding positions are occupied by identical amino acid residues. Much of the variability occurs in a short polar region of 20 amino acid residues. The remainder of C‐terminal regions is hydrophobic and almost completely invariable.A comparison of the amino‐terminal one third of H2B(1) Parechinus and H2Bcalf reveals that they are both highly basic with a considerable homology of the position of basic amino acids. Further, H2B(1) Parechinus possesses an amino terminal extension of 19 amino acids. These 19 amino acids can be recognized as a repeating pentapeptide.