bluuebunny/crossref_metadata_2025_split huggingface dataset:
Nucleotide Sequence of the Simian‐Virus‐40 DNA Region Coding for the Carboxyl‐Terminal Part of the T Antigen
Authors: VAN HEUVERSWYN Hugo , VAN DE VOORDE André , FIERS Walter 
Published: March 2005

Fragment Hind‐B‐C2, the second largest DNA restriction fragment generated by digestion of fragment Hind‐B with the endo R ·EcoRII enzyme, represents 4.4% of the Simian virus 40 (SV40) genome. The complete nucleotide sequence (231 base pairs) of this fragment has been determined by application of the procedure of Maxam and Gilbert (1977). This region is believed to code for the carboxyl‐terminal part of the T antigen. On the basis of the termination code words in the strand with the same polarity as the early mRNA, two open reading frames for translation could be defined. Only one of these, however, extends through the adjacent Hind‐B‐Ci fragment and is therefore believed to dictate the primary structure of the T antigen. It terminates within Hind‐B with a TAA signal. The region, determined by the second open frame, is large enough to code for a protein of Mr about 11000.The regions in SV40 DNA from which the non‐translated regions of the early and late mRNAs are transcribed overlap over nearly their entire length. Although this spacer region is very (dA + dT)‐rich, a secondary structure model can be proposed which is centered around map position 0.17. The RNA copy of the untranslated region also contains the sequence A‐A‐U‐A‐A‐A, common to all other eukaryotic mRNA molecules sequenced so far; it is present once on the late mRNA and twice on the early messenger RNA. Also a sequence of 6 or 7 successive thymidine residues is present in the early and late DNA strand respectively, 131 and 95 nucleotides beyond the polypeptide termination codons, and these may perhaps play a role in termination of transcription.Of particular interest may be the carboxyl terminus of the T antigen; the terminal tryptic peptide is 10 residues long, six of which are proline.
Isolation and Chemical Characterization of the Enterobacterial Common Antigen
Authors: MÄNNEL Daniela , MAYER Hubert 
Published: March 2005

The isolation of the soluble form of the Enterobacteriaceae common antigen from Salmonella montevideo was achieved by a combination of the phenol/water method and the phenol/chloroform/petroleum ether extraction procedure. A phenol‐soluble fraction highly enriched in the antigen was obtained which was further purified by DEAE‐cellulose chromatography. A fraction eluted with 0.9 M ammonium acetate/methanol was highly active in coating erythrocytes for passive hemagglutination with antisera specific for enterobacterial common antigen and was an active inhibitor of the hemagglutinating system for this antigen.Chemical analyses showed enterobacterial common antigen to be a linear polymer of 1,4‐linked N‐acetyl‐d‐glucosamine and N‐acetyl‐d‐mannosaminuronic acid units esterified to a small extent by palmitic and acetic acids. These amino sugar and fatty acid components represent about 65–70% of the material. The presence of additional still unknown lipid components which might account for the missing 30% and for the low solubility of the isolated antigen in water is discussed. The molecular weight of the readily soluble part of the inhomogeneous isolated enterobacterial common antigen was determined by sedimentation studies in an analytical ultracentrifuge using methanol as solvent; it was found to be 2700.
Serological and Immunological Properties of Isolated Enterobacterial Common Antigen
Authors: MÄNNEL Daniela , MAYER Hubert 
Published: March 2005

Enterobacteriaceae common antigen (sometimes abbreviated to ECA) isolated from Salmonella montevideo by a combination of phenol/water and phenol/chloroform/petroleum ether extraction procedures and further purified by ion‐exchange chromatography was investigated relative to its serological and immunological properties.The isolated material was highly active in coating erythrocytes for agglutination with antisera specific for enterobacterial common antigen and in inhibition of hemagglutinating systems established for this antigen. With some high‐titered antisera to enterobacterial common antigen the material precipitated in a characteristic bird‐wing pattern after immunoelectrophoresis at pH 8.6. Alkalitreated material gave a single precipitin line indicating that it was more uniform than the untreated enterobacterial common antigen, which was probably partly cross‐linked. An additional weak precipitin line, located close to the antiserum trough, was occasionally observed. Specific serum absorptions with genetically defined ECA‐negative rfe− or rff− mutants did not influence the precipitation pattern at all, whereas similar absorptions with living or heat‐killed ECA‐positive strains removed all precipitating antibodies.Esterification of the carboxylic groups of the D‐mannosaminuronic acid residues in enterobacterial common antigen leads to a reversible loss of its precipitating capacity, proving that this aminuronic acid is an essential part of the serological determinant of this antigen.Attempts to immunize rabbits with the isolated, soluble enterobacterial common antigen were unsuccessful. High titers were, however, elicited in rabbits and NMRI mice when the immunization was carried out with the antigen attached to acetic‐acid‐hydrolyzed S. minnesota R595 bacteria according to the technique of Galanos. The specificity of the immune response was ascertained by absorbing the sera with closely related pairs of ECA‐positive and ECA‐negative enterobacterial strains.The data show that the material isolated as enterobacterial common antigen from S. montevideo has retained the serological and immunological characteristics of the antigen which was first described and defined by Kunin.
Cytochrome c from Schizosaccharomyces pombe
Authors: CLAISSE Maurice L. , SIMON‐BECAM Anne‐Marie 
Published: March 2005

Cytochrome c from the fission yeast Schizosaccharomyces pombe has been purified. Its chromato‐graphic and spectral properties are reported and compared to those of iso‐1‐cytochrome c from baker's yeast; the amino‐acid composition is described. Schiz. pombe cytochrome c has a much lower affinity for Amberlite IRP64 than Sacch. cerevisiae iso‐1‐cytochrome c. Its α absorption band splits into three maxima (cα1, cα2, and cα3) at −190°C; this is unusual in yeasts, as shown by the low‐temperature whole‐cell absorption spectra which were examined in various yeast genera, species, and strains.A minor component can be separated by Amberlite chromatography. It exhibits the same low‐temperature splitting of the α absorption band as the main fraction and it has a similar amino‐acid composition with a notable exception: it is an unmethylated form of the cytochrome.
Calsequestrin, Myosin, and the Components of the Protein‐Glycogen Complex in Rabbit Skeletal Muscle
Authors: CAUDWELL Barry , ANTONIW John F. , COHEN Philip 
Published: March 2005

The protein‐glycogen particle preparation isolated from rabbit skeletal muscle extracts by mild acidification and differential centrifugation shows eight major protein‐staining bands when examined by polyacrylamide gel electrophoresis, five of which have previously been identified as the glycogen debranching enzyme, the α and β subunits of phosphorylase kinase, glycogen phosphorylase and glycogen synthase [Taylor, C., Cox, A. J., Kernohan, J. C. & Cohen, P. (1975) Eur. J. Biochem. 51, 105–115].The other three major proteins in this preparation have now been identified. Two of the proteins were identified as the heavy chain of myosin and actin respectively, based on their electrophoretic migration, their insolubility in buffers of low ionic strength, and their solubility in buffers containing 0.6 M KCl.The third protein has been found to be calsequestrin, a major calcium‐binding protein of the sarcoplasmic reticulum. This conclusion was based on the unusual chromatographic behaviour of the protein on DEAE‐cellulose at pH 7.5, its electrophoretic mobility, amino acid composition, and immunological cross reactivity.A simple method for the isolation of calsequestrin as a by‐product of the purification of glycogen synthase has been developed, by which 70–80 mg of the protein were routinely isolated from 5000 g of muscle (6 rabbits) within five days. The protein was homogeneous by the criterion of polyacrylamide gel electrophoresis and sedimentation equilibrium centrifugation. The molecular weight determined by the latter technique was 41000 and the absorbance index A280 nm1%, was 11.7. The protein had a very low sedimentation coefficient of 1.97 S indicating that it is either very asymmetric or a largely unfolded protein, in the buffers used in these experiments, a conclusion supported by its abnormal gel filtration behaviour.Since the three hitherto unidentified components of the protein‐glycogen particle preparation are not enzymes of glycogen metabolism and merely constituents of particulate material (actomyosin and fragments of the sarcoplasmic reticulum) which have coprecipitated with the protein‐glycogen complex, over 95% of the protein attached to glycogen is accounted for by just four enzymes.
Compound I Formation with Turnip Peroxidases and Peroxybenzoic Acids
Authors: JOB Dominique , JONES Peter 
Published: March 2005

The kinetics of formation of the compounds I of the turnip peroxidase isoenzymes 1 and 7 with peroxybenzoic acid and a series of substituted peroxybenzoic acids (p‐OCH3, p‐CH3, p‐Cl, m‐Cl, m‐NO2 and p‐NO2) were studied at 25°C. The pH profiles of the observed second‐order rate constants, after correction for the alkaline transitions of the enzymes, indicate that isoenzyme 1 reacts exclusively with unionized peroxy acids whereas with isoenzyme 7, although the major contribution involves reaction with unionized peroxy acid, an additional reaction with peroxy anion is observed. In contrast to the behaviour of horse‐radish peroxidase, (where the rate constants for unhindered unionized peroxybenzoic acids exceed that with H2O2 and the reactions are probably diffusion controlled) the rate constants, kHA, for isoenzyme 1 reaction with unionized peroxy acids are all lower than that with H2O2 and the activation energies indicate chemical control. For isoenzyme 7 the value of kHA with the most weakly acidic peroxybenzoic acids exceeds the rate constant with H2O2. For both isoenzyme 1 and isoenzyme 7 the values of kHA are very sensitive to peroxy acid acidity and in both cases log kHA shows good correlation with pKHA.The results are compared with each other and with previous data for both turnip and horse radish peroxidases. It is suggested that the multifactorial influences upon the kinetics of compound I formation include (a) diffusion, (b) substrate hydrophobicity, the hydrophobic binding affinity of the active sites of the enzymes and perhaps hydrogen bonding interactions, (c) a substrate‐charge‐type discrimination elicited by the protein at the entrance to the active site, (d) substrate substituent inductive effects which suggest the importance of the generation of highly nucleophilic peroxy anions from neutral hydroperoxides within the active site. These influences are of very variable relative importance in enzymes from different sources and in different isoenzymes from the same source.
The Influence of Prolonged Ethanol Intake on the Levels and Turnover of Alcohol and Aldehyde Dehydrogenases and of Brain (Na + K)‐ATPase of Rats
Authors: GUERRI Consuelo , WALLACE Ruth , GRISOLIA Santiago 
Published: March 2005

Levels of liver alcohol dehydrogenase, liver mitochondrial aldehyde dehydrogenase and brain (Na + K)‐stimulated ATPase were determined in control rats and in rats fed an ethanol liquid diet for 7 weeks. The alcohol dehydrogenase level did not change with the diet; however, the levels of mitochondrial aldehyde dehydrogenase and of the (Na + K)‐ATPase were increased 2.5‐fold and 2‐fold respectively.Also, the levels of these enzymes from brain and liver fractions of rats given a 20% ethanol solution as the sole drinking fluid were determined at intervals from 4 to 18 weeks. A progressive increase was found in the level of aldehyde dehydrogenase and of ATPase.To ascertain whether synthesis or degradation of these enzymes were responsible for the marked increase in activity the turnover of several liver fractions and of the indicated enzymes were measured by the dual‐labelled isotope technique. Long‐term ethanol administration did not affect the rate of turnover of the liver cell fractions except for the mitochondrial fraction. This fraction showed a marked decrease in the rate of degradation. The degradation constant of the liver alcohol dehydrogenase did not change; however, the rate of degradation of liver mitochondrial aldehyde dehydrogenase (low‐Km) and of brain (Na + K)‐ATPase was decreased.
The Regulation of Glycogen Metaabolism
Authors: NIMMO Gilllian A. , COHEN Philip 
Published: March 2005

Inhibitor‐1 is a protein which inhibits phosphorylase phosphatase only when it has been phosphorvlated by cyclic‐AMP‐dependent protein kinase [Huang, F. L. and Glinsmann. W. H. (1976) Eur. J. Biochem. 70, 419–426].Inhibitor‐1 was purified by a heat treatment at 90°C, precipitation with ammonium sulphate, chromatography on DEAE‐cellulose, gel filtration on Sephadex G‐100, and finally recromatography of the phosp0horylated protein on DEAE‐cellulose. The protein was purified 4000‐fold and 1.5 mg per 1000 g muscle was obtained in seveven days corresponding to an overall yield of 15–20%. The purified protein was in a state approaching homogeneity as judged by the criteria of polyacrylamide‐gel electrophoresis and ultracentrifugal analysis. The concentration of inhibitor‐1 in vivo was calculated to be 1.5 μMM, which is at least as high as the concentrationof phosphorylase phosphatase.The amino acid composition of inhibitor‐1 showed several unusual features. Glutamic acid and proline accounted for nearly one third of the residues, tyrosine, tryptophan and cysteine were absent, and the content of aromatic amino acids was very low.The molecular weight measured by sedimentation equilibraium centrifugation was 19 200 and by amino acid analysis was 20 800. These values were lower than the mol. wt of 26000 determined empirically by gel electrophoresis in the presence of sodium dodecyl sulphate, and much lower than the apparent molecular weitht of 60000 estimated by filtraation on Sephadex G‐100. The gel filtration behaviour, stability to heating at 100°C and amino acid composition suggest than inhibitor‐1 may possess little ordered structure.The phosphorylated form of inhibitor‐1contained close to one molecule of covalently bound phosphate per mole of protein, which is consistent with previous finding of a unique decapeptide sequence at the site of phosphorylation, Ile‐Arg‐Arg‐Arg‐Arg‐Pro‐Thr(p‐Pro‐Ala‐Thr‐[Cohen, P., Rylatt, D. B. and Nimmo, G. A. (1977) FEEBS Lett. 76, 182–186].The phosphorylated form of inhibitor‐1 inhibited phosphorylase activity (0.02 U) by 50% at a concentration of only 7.0 nM in the standard assay, but the phosphorylated decapeptide was 1000–2000 times less effective as an inhibitor.
Purification and Regulation of Glucose‐6‐Phosphate Dehydrogenase from Obligate Methanol‐Utilizing Bacterium Methylomonas M15
Authors: STEINBACH Rolf A. , SAHM Hermann , SCHÜTTE Horst 
Published: March 2005

Glucose‐6‐phosphate dehydrogenase has been purified 192‐fold from Methylomonas M15 grown on methanol as sole source for carbon and energy. The purification procedure involved N‐cetyl‐N,N,N‐trimethylammonium bromide precipitation, ion‐exchange chromatography and affinity chromatography on blue‐dextran‐Sepharse. The final enzyme preparations were homoveneous as judged by acrylamide gel electrophoresis and by sedimentation in an ultracentrifuge. The molecular weight of the enzyme was calculated to be 108000 ± 5000 from sedimentation equilibrium experiments. Electrophoresis in sodium dodecylsulfate gels indicates that the enzyme is a dimer composed of two probably identical subunits each having a molecular weight of 55000.The enzyme exhibits activity with either NAD or NADP as electron acceptor. Mg2+ or an other biblent cation is not essential for enxyme activity. The Kmvalues were found to be 0.2 mM for NAD, 0.014 mM for NADP, 0.29 mM for glucose 6‐phosphate with NAD and 0.11 mM for glucose 6‐phosphate with NADP as electron acceptor. The reduced coenzymes NADPH and NADH as well as ATP are powerful inhibitors of the enzyme.The intracellular levels of glucose 6‐phosphate, ATP, NAD and NADP were measured and found to be approximately 2.5 mM, 1.5 mM, 1 mM and 2 mM respectively, during exponential growth. From a consideration of the substrate pool sizes and types of inhibitors, it is concluded that this enzyme may function in two roles in the cell: NADH reproduction for energetics and NADPH production for reductive biosynthesis.
γ‐Glutamyl Transpeptidase: Sidedness of Its Active Site on Renal Brush‐Border Membrane
Authors: HoRIUCHI Seikoh , INOUE Masayasu , MORINO Yoshimasa 
Published: March 2005

Sidedness of γ‐glutamyl transpeptidase, an integral glycoportein of rat renal brusch border membrane, was investigated and the active siyte of the membrane‐bound enzyme was shown to face to the luminal side of the renal tubules on the basis of the two following observations. First, γ‐glutamyl transpeptidase activity exhibited by purified brush border membrane vesicles was effectively inhibited by an S‐acetyldextran polymer (molecular weight: 215 000) derivative ofglutathione, which is believed to be impermeable through plasma membranes. Secondly, the membrane‐bound γ‐glutamyl transpeptidase was quantitatively released by treating vesicles with papain immobilized to Sephadex G‐10 beads.Strict stoichiometry of affinity labeline of rat renal γ‐glutamyl transpeptidase, which possesses one active site per molecule [Inoue, M., Horiuchi, S., and Morino, Y. (1977) Eur. J. Biochem. 73, 335–342; Tate, S. S., and Meister, A. (1977) Proc. Natl Acad. Sci. U.S.A. 74, 931–935], was utilized to compare the molecular size of the detergent‐solubilized enzyme with that of the papain‐solubilized enzyme. Thus, 1 mol redioactive 6‐diazo‐5‐oxo‐l‐norleucine was covalently incorporated into 102000 g detergent‐solubilized enzyme and 64000 g papain‐solubilized enzyme. Both enzyme foorms of γ‐glutamyl transpeptidase are composed of two non‐identical subunits, the large and the small subunit. Molecular weightgs of these subunits were determined in sodium dodecylsulfate/polyacrylamide gel electrophresis from the retardation coefficients obtained from Ferguson plots. The result indicated the size difference between these two enzyme forms could be largely accounted for by the size difference in the large subunits. Thus, iot is likely that the oligomeric γ‐glutamyl transpeptidase was anchored into the brush nborder membrane mainly via te large subunit of tghe enzyme.
Homologous RNA Polymerase binding to Escherichia coli DNA
Authors: PEDONE Francesco , BALLARIO Paola , DI MAURO Ernesto 
Published: March 2005

The number and the distribution of the sites of Escherichia coli DNA that from stable complexes with the homologous RNA polymerase (class A sites according to Hinkle and Chamberlin [3]) have been investigated. Almost all the DNA can bind RNA polymerase, even when fragmented at short (undergenic) size; this general non‐promoter‐specific binding is highly labile and is not temperature‐dependent. The range of RNA polymerase DNA ratios that give rise to the stable temperature‐dependent complexes was examined.The amount and the distribution of class A complexes were studied analysing the dissociation of complexes formed by RNA polymerase on DNA fragments of various length. The E. coli genome appears to form 3.8 × 103 stable complexes; the majority of these complexes shows a short‐range distribution (800–1200 base pairs). The rest is more widely spaced (1200–6000 base pairs).
A Structural Model of Cholinergic Synaptic Vesicles from the Electric Organ of Torpedo marmorata Deuduced from Density Measurements at Different Osmotic Pressures
Authors: BREER Heinz , MORRIS Stephen J. , WHITTAKER Victor P. 
Published: March 2005

Density measurements made on cholinergic synaptic vesicles from the electric organs of Torpedo marmorata at different osmotic pressures are consistent with the following structural model of the vesicle.The particle behaves like a sphere 80–100 nm in diameter bounded by a semi‐permeable membrane. The bulk of its soluible constituents are in true solution at physiologica osmolalities. The limiting mambrance is approximately 4–5‐nm thick, suggesting that it contains large areas of phospholipid bilayer exposed to its bathing medium.The limiting membrane takes up abouit 26% (v/v) of the particle, a further 34% (v/v) of which is osmotically active water and 31% (v/v) hydrated core material at 800 mosmol/l. The byouant density of the membrane is 1.132 g · cm−3. the density of the hydrated core material is approximately 1.05 g · cm−3.The membrane is selectively permeable to small molecules when subjected to hypo‐osmotic stress. It is proposed that this occurs by the formation of small transient pores in the lipid bilayer of the membrane, which are induced by stretching caused by the osmotic pressure change.
Structural Studies of Iron and Cobalt Tetrasulfonated Phthaslcyanine‐Globin Complexes
Authors: PRZYWARSKA‐BONIECKA Helena , TRYNDA Liliana 
Published: March 2005

The structue of the complexes of iron and cobalt tetrasulfonated phthlaocyanines with globin has been investigated by circular dichroism (CD), electron paramagnetic resonance (EPR) and polyacrylamide gel electrophoresis.Electrophoretic investigations and the molecular weight estimation indicates that the model complexesin the solutionss are dimers.It is evident from the results of CD measurements that the incorporation of the iron or cobalt tetrasulfonated phthalocyanine into apohemoglobin significantly increases the helical structure oif the protein and causes an appearance of the induced Soret and visible Cotton effects. Unlike methemoglobin, several discrete transition energies in the CD Soret band of FE(III)L‐globin are oberved which suggests an inequivalence of the subunits within this complex. This suggestion is supported by EPR studies, which show that the iron atoms in Fe(III)L‐globin are in two low electronic states. Ele3ctronic structures of the cobalt ions in Co(II)L‐globin and oxyCo(II)L‐globin are similsar to those of coboglbin asnd oxycoboglobin, repsectively, as is proved by EPR results. On this basis we conclude that the oxygen adduct of Co(II)L‐globin can be described as a superoxide ion corrdinated to a formaslly cobaltic phthalocyanine compound.