bluuebunny/crossref_metadata_2025_split huggingface dataset:
Interactions of Heteroaromatic Compounds with Nucleic Acids
Authors: MÜLLER Werner , BÜNEMANN Hans , DATTAGUPTA Nanibhushan 
Published: March 2005

This paper presents the results of a systematic study on the effects of substituents on the base and sequence specificity of tricyclic heteroaromatic compounds interacting with DNA by intercalation. All the compounds tested are derived from proflavine and acridine orange analogs with different heteroatoms in the middle ring. Their base and sequence specificities were determined by differential dialysis of the ligand against DNA samples of differing G · C content. The main results indicate that (a) the introduction of a phenyl substituent into one of the two available positions of the middle ring increases or decreases the G · C specificity of the ligand depending on the position where the substitution takes place; (b) compounds of the substitution type of neutral red (2‐methyl‐3‐amino‐7‐dimethyl‐amino‐phenazine) show unexpectedly high G · C specificities and (c) DNA ligands of pronounced sequence specificity for adjacent G · C pairs can be constructed by combining the structural elements of neutral red with an additional phenyl residue in the same molecule.The further study of compounds related to the phenylated neutral red revealed that the G · C specificity can be improved or destroyed by additional substituents.The comparison of the G · C specificity and the DNA‐affinity data of the compounds studied leads to the suggestion that the specificity arises mainly from electronic factors which are strongly controlled through steric constraints on possible complex geometries. As a basis for the discussion a possible structure for the DNA complex of the phenylated neutral red is considered in which the extra phenyl ring at N‐5 of the phenazinium system, protrudes into the large groove of the DNA helix while the tricyclic part of the ligand is inserted between the DNA base‐pairs.
The Stimulation of Liver Phosphorylase b by AMP, Fluoride and Sulfate
Authors: STALMANS Willy , HERS Henri‐Géry 
Published: March 2005

The activity of liver phosphorylase b from several mammalian species has been studied. The enzyme from rat or mouse has a higher activity than the rabbit enzyme, which is itself more active than pig liver phosphorylase b.
The activity of liver phosphorylase b is influenced by anions and by AMP, and these effects are influenced by pH. Fluoride, which is currently added to the assay mixture of phosphorylase a in crude preparations, is about as active as sulfate as a stimulator of phosphorylase b.
When assayed at pH 6.1 and in the presence of 0.15 M NaF, the activity of rat liver phosphorylase b reaches 25% of that of the a enzyme; if 1 mM AMP is also present, this value rises to 50%.
Methods are described that allow the determination of liver phosphorylase a without interference of b, and the determination of total phosphorylase (a+b) in rat liver.
Non‐Helical Sequences of Rabbit Collagen
Authors: BECKER Udo , FIETZEK Peter P. , TIMPL Rupert , FURTHMAYR Heinz 
Published: March 2005

Non‐helical peptide fragments were isolated from rabbit skin collagen after cleavage of α chains with cyanogen bromide and proteases. Determination of their amino acid sequence indicated a length of 9, 16 and 25 amino acid residues for the non‐helical sequences located in the N‐terminal region of α2 and α1 chain and in the C‐terminal region of α1 chain, respectively. The C‐terminal sequence Tyr‐Tyr hitherto considered as the genuine end of collagen α 1 chain is in part of rabbit collagen extended by two residues, alanine and arginine.Rabbit collagen may differ considerably in its non‐helical sequences from other vertebrate col‐lagens, particularly in the C‐terminal part. Some but not all of these differences are clustered in areas occupied by antigenic determinants which are recognized in the antibody response of rabbits to rat or calf collagen. On the other hand, a high homology to rabbit collagen, e.g. in the N‐terminal region of rat collagen α1 chain or calf collagen α2 chain, probably prevents immunological recognition by the rabbit. The degree of foreignness alone, however, may not necessarily determine whether a particular non‐helical area is able to express immunogenic activity.
Reassociation Kinetics of Deoxyribonucleic Acid in Antigen‐Stimulated Mouse‐Spleen Cells
Authors: MOAV Neomi , FRENSDORFF Asher , MOAV Boaz 
Published: March 2005

In order to directly compare the complexity of the genome of lymphoid cells which have been antigenically stimulated, with that of non‐immunized and non‐lymphoid cells, DNA was pulse labeled and extracted from BALB/c mouse spleen cells at various time intervals after antigenic stimulation in vivo; the reassociation rates of these newly synthesized DNA preparations were compared with those of the total mouse spleen DNA, obtained from the same sources and at the same times.DNA labeled for 60 min at 43, 53, or 72 h after antigenic restimulation, reassociated faster than the corresponding total DNA. On the other hand, the reassociation profile of DNA, labeled for 60 min during the first 24 h after restimulation did not differ from that of the total DNA extracted at the same time. When labeled thymidine was available for incorporation at a constant concentration over a period of 24 h, reassociation patterns of labeled DNA were identical to those of the corresponding total DNA at all times after restimulation. Newly synthesized nuclear DNA exhibited reassociation profiles identical to those of the corresponding total nuclear DNA at all times tested. Also, no differences between the reassociation rates of nuclear and total cellular DNA were observed.It was concluded that antigenic stimulation does not induce a major amplification of genes in the stimulated cells, and that the rapidly reassociating DNA species described represent extranuclear (cytoplasmic) DNA.
The Biosynthesis of Basement‐Membrane Collagen by Isolated Rat Glomeruli
Authors: GRANT Michael E. , HARWOOD Richard , WILLIAMS Isabel F. 
Published: March 2005

A technique is described for the rapid isolation of highly purified preparations of viable glomeruli from rat kidney cortex. The synthesis of protein as judged by the incorporation of [14C]proline into non‐diffusible material was shown to be linear for up to 6 h. The synthesis of collagen, measured as non‐diffusible 4‐hydroxy[14C]proline, was also linear over this period but represented only a small proportion of total protein synthesis. Similar studies conducted in vivo confirmed that collagen synthesis accounted for less than 5% of total protein synthesis in glomeruli.When isolated glomeruli were incubated with [14C]proline, it was found that approximately 16% of the hydroxyproline present in the collagenous component occurred as the 3‐isomer. When glomeruli were incubated with [14C]lysine over 90% of the hydroxy[14C]lysine synthesised was glyco‐sylated and most of the glycosylated hydroxy[14C]lysine was present as glucosyl‐galactosyl‐hydroxy‐[14C]lysine.The size of the basement membrane collagen synthesised by the isolated glomeruli was estimated by treating the 14C‐labelled protein with mercaptoethanol and sodium dodecyl sulphate and then chromatographing the 14C‐labelled protein on an agarose column equilibrated and eluted with buffer containing 0.1% (w/v) sodium dodecyl sulphate. The initial form of [14C]collagen synthesised was found to consist of polypeptide chains which had molecular weights of approximately 140000 and which were shown to be distinctly larger than the polypeptide chains from embryonic chick tendon procollagen. Also when glomeruli were labelled with [14C]proline for 2 h and chased with unlabelled proline for 4 h there was a time‐dependent conversion of the initially synthesised collagen moiety to collagen polypeptide chains which co‐chromatograph with tendon pro‐α chains (molecular weight approx. 120000).
The Amino‐Acid Sequence of Leghemoglobin Component a from Phaseolus vulgaris (Kidney Bean)
Authors: LEHTOVAARA Päivi , ELLFOLK Nils 
Published: March 2005

Leghemoglobin component a from Phaseolus vulgaris (kidney bean) was digested with trypsin; 15 tryptic peptides and free lysine were purified and the amino acid sequences of the peptides deter mined.
The internal order of the tryptic peptides was determined by the bridge peptides obtained from the thermolytic digest and the dilute acid hydrolyzate of kidney bean leghemoglobin a; 12 thermolytic peptides and two acid hydrolysis peptides were purified and the sequences were partially or completely determined.
The complete amino acid sequence of kidney bean leghemoglobin a is compared to that of leghemoglobin a from soybean (Glycine max) and to some animal globins. As regards sequence, the kidney bean globin has 79% identity with the soybean globin and 21% identity with human hemoglobin γ‐chain. Seven of the 14 amino acid residues common to most globins are found in the kidney bean globin. Trp‐15 and Tyr‐145 are evolutionarily conserved in this globin, which confirms the concept of a common origin of animal and plant globins.
Purification of Rheumatoid Synovial Collagenase and Its Action on Soluble and Insoluble Collagen
Authors: WOOLLEY David E. , GLANVILLE Robert W. , CROSSLEY Malcolm J. , EVANSON John M. 
Published: March 2005

The neutral collagenase released into the culture medium by explants of rheumatoid synovial tissue has been purified by ultrafiltration and column chromatography, utilising Sephadex G‐200, Sephadex QAE A‐50 and Sephadex G‐100 superfine.
The final collagenase preparation had a specific activity against thermally reconstituted collagen fibril of 312 μg collagen degraded min−1 mg enzyme protein−1, representing more than a 1000‐fold increase over that of the active culture medium.
Electrophoresis in polyacrylamide disc‐gels with and without sodium dodecyl sulphate showed the enzyme to migrate as a single protein band. Elution experiments from polyacrylamide gels and chromatography columns have provided no evidence for the existence of more than one collagenase.
The molecular weight of the enzyme, as determined by dodecylsulphate‐polyacrylamide gel electrophoresis, was 33000.
Data obtained from studies with the ion‐exchange resin and from gel electrophoresis in acid and alkaline buffer systems suggested a basically charged enzyme.
It did not hydrolyse the synthetic collagen peptide Pz‐Pro‐Leu‐Gly‐Pro‐d‐Arg and non‐specific protease activity was absent.
The collagenase attacked undenatured collagen in solution at 25°C resulting in a 58% loss of viscosity and producing the two characteristic products TCA (3/4) and TCB (1/4).
At 37°C and pH 8.0 both reconstituted collagen fibrils and gelatin were degraded to peptides of less than 10000 molecular weight.
As judged by the release of soluble hydroxyproline peptides and electron microscopic appearances the enzyme degraded human insoluble collagens derived from tendon and soft juxta‐articular tissues although rates of attack were less than with reconstituted fibrils.
The data suggests that pure rheumatoid synovial collagenase at 37°C and neutral pH can degrade gelatin, reconstituted fibrils and insoluble collagens without the intervention of non‐specific proteases.
The different susceptibilities of various collagenous substrates to collagenase attack are discussed.
Thermal and Solvent Perturbation as Probes of Conformational Heterogeneity of Haptoglobin 1‐1
Authors: de FORESTA Béatrice , LAVIALLE Françoise , ALFSEN Annette 
Published: March 2005

The shifts which occur in the ultraviolet spectra of haptoglobin 1‐1 (Hp) and a conformational isomer with lower affinity for hemoglobin (Hp*), in response to temperature and solvent changes, have been measured by difference spectra. The thermal difference spectra provide evidence for a different participation of tryptophyl residues in the conformational stability of Hp and Hp*. Solvent perturbations have allowed an estimation to be made of the number of surface chromophores in the native Hp and Hp*.These results are compatible with the existence of two Hp conformational isomers with different free energy, separated by a high‐potential barrier.
Multiple Forms of Human Glutathione S‐Transferase and Their Affinity for Bilirubin
Authors: KAMISAKA Kazuaki , HABIG William H. , KETLEY Jeanne N. , ARIAS Irwin M. , JAKOBY William B. 
Published: March 2005

The initial enzymic step in mercapturic acid formation is catalyzed by glutathione S‐transferase. Several species of this enzyme, designated as transferases α. β, γ, δ and e an the basis of increasing isoelectric points, were isolated from human liver. Evidence is presented that each of the purified species is homogeneous with respect to sodium dodecylsulfate‐gel electrophoresis. Transferases α, β and ɛ each appear as a single band an gel electrofocusing: transferases α and δ are present as two and three bands, respectively, with each band catalytically active. Amino acid analysis indicated the five transferases to be either very closely related or identical in this respect.All enzyme species have a molecular weight of about 48 500 and consist of two apparently identical subunits. The spectrum of substrates is the same for each although the enzymes differ slightly in specific activity. As is the case for the rat liver enzymes, each of the human transferases binds bilirubin although this compound is not a substrate
ADP‐Ribosylation of DNA‐Dependent RNA Polymerase of Escherichia coli by an NAD+: Protein ADP‐ribosyltransferase from Bacteriophage T4
Authors: ROHRER Hermann , ZILLIG Wolfram , MAILHAMMER Reinhard 
Published: March 2005

A protein from bacteriophage T4 responsible for the alteration of host DNA‐dependent RNA polymerase and absent in T4 alt− phage was purified from T4 phage and enriched from T4‐infected cells. It is injected during infection together with the known internal proteins. It has a molecular weight of about 70000 and catalyses the release of nicotinamide and the transfer of the ADP‐ribosyl moiety from NAD+ to arginyl residues of various proteins including itself.RNA polymerase from Escherichia coli accepts ADP‐ribosyl residues in all four subunits; the α subunit reacts with very high specificity. Only half of the α subunits are labelled, 45 with one, 5 % with two residues. The main product shows the same electrophoretic mobility as α subunits altered or modified in vivo. The a subunit in modified RNA polymerase is no acceptor.
The Trypsin and Chymotrypsin Inhibitors in Chick Peas (Cicer arietinum L.)
Authors: BELEW Makonnen , PORATH Jerker , SUNDBERG Lars 
Published: March 2005

From a crude extract of chick peas (Cicer arietinum L.) inhibitors of trypsin and chymotrypsin were isolated by affinity chromatography on a column of trypsin‐Sepharose 6B. The content of inhibitors was found to be 1.5 g/kg. They were further separated into six isoinhibitors by ion‐exchange chromatography on DEAE‐Sephadex A‐25. Two of the isoinhibitors accounted for about 50 % of the isolated inhibitors and were further purified to a homogeneous state.The isoinhibitors had a molecular weight of about 10000 as determined by molecular‐sieve chromatography on Sephadex G‐75. They were stable towards extremes of pH and temperatures up to 75 C or towards digestion by pepsin. They were also stable in 6 M urea but not in 6 M guanidineHCI. The intact inhibitors were destroyed when the peas were cooked at 100°C or when they were toasted at 130°C.The four major inhibitors had similar amino acid compositions and did not contain detectable amounts of free sulfhydryl groups, tryptophan or carbohydrate. Cysteine is the dominant amino acid residue in all of them and accounted for about 20 % of their amino acid content. The isoelectric point of the isoinhibitors lies in the range of pH 4.9‐8.6 and two of the major inhibitors had isoelectric points of pH 4.75 and pH 4.96. They inhibited chymotrypsin to the same extent but differed in their inhibitory activities towards trypsin, indicating that they are mixtures of native and trypsinmodified forms and that they probably have separate sites for the two enzymes. They did not inhibit other proteolytic enzymes belonging to two groups (i.e., serine or cysteine enzymes) or originating from different sources (i.e., animals, plants or bacteria).
The Major Proteins of the Escherichia coli Outer Cell‐Envelope Membrane
Authors: GARTEN Wolfgang , HINDENNACH Ingrid , HENNING Ulf 
Published: March 2005

The cyanogen bromide fragments of protein I, a major protein of the Escherichia coli outer cell envelope membrane, have been isolated and characterized. There appear to be two methionineserine or methionine‐threonine sequences causing incomplete cleavage but complete conversion of methionine to homoserine. Largely due to the existence of these overlapping fragments the order of 5 of the 6 fragments present could be deduced.None of the fragments exhibits any remarkable low degree of polarity, and the tryptic fingerprint of the largest fragment (comprising about 60% of protein I) also does not show any conspicuous large fraction of lipophilic peptides. It is concluded that the domain of protein I that may be buried in the lipid phase of the outer membrane in all likelihood is not very large, and there is, in fact, no definite proof yet that protein I is a membrane protein sensu stricto.
Time‐Dependent Inhibition of Diamine Oxidase by Carbonyl‐Group Reagents and Urea
Authors: CRABBE M. James C. , CHILDS Robert E. , BARDSLEY William G. 
Published: March 2005

The behaviour of several carbonyl group reagents and urea as time‐dependent inhibitors of both pig kidney and human placental diamine oxidase is described.
Plots of log (vt/v0) against time were not linear with these reagents as the usual theories predict.
This was particularly the case with aminoguanidine and phenylhydrazine and a thorough study of the effects of these compounds on the human placental diamine oxidase is described.
By applying a new theory for time‐dependent inhibition, the inhibition of diamine oxidase by aminoguanidine and phenylhydrazine is adequately accounted for.
The time‐dependent recovery of activity on addition of sodium pyruvate suggested that the compounds used are acting solely as carbonyl group reagents, inhibiting by Schiff‐base formation at the active‐site carbonyl group.
The Interaction of Organic Phosphates with Human and Chicken Hemoglobin
Authors: BRYGIER Jeanne , DE BRUIN Simon H. , VAN HOOF Peter M. K. B. , ROLLEMA Harry S. 
Published: March 2005

In this study the binding properties of inositol hexaphosphate and 2,3‐bisphosphoglycerate to chicken and human deoxyhemoglobin and carboxyhemoglobin were compared. It appeared that in all cases the binding to chicken hemoglobin is much stronger than to human hemoglobin. This is very probably due to the fact that 4 out of the 12 residues, responsible for the binding of phosphates in chicken hemoglobin, are arginines. These are absent in human hemoglobin, where the binding site is made up by only 8 residues.For chicken hemoglobin one strong binding site could be observed in both unliganded and liganded hemoglobin. From these observations we conclude that the same binding site is involved in both the oxy‐ and deoxy structure showing a different affinity to phosphates in the two conformational states. For human hemoglobin we reached the same conclusion.
Hepatic Nucleases
Authors: BARTHOLEYNS Jacques , PEETERS‐JORIS Chantal , BAUDHUIN Pierre 
Published: March 2005

In the large granule fraction of rat liver, the density distribution of inhibitor‐sensitive neutral ribonuclease is similar to that for acid hydrolases and its density distribution is similarly modified by Triton WR‐1339 accumulation in lysosomes. Particulate neutral ribonuclease is latent; the enzyme is unmasked by very low digitonin concentrations or hypoosmotic shock. These observations demonstrate that the bulk of liver neutral ribonuclease is associated with the lysosomal system.In view of the neutral pH optimum of the enzyme and of some particularities of its distribution in fractionation experiments, the possibility of an extrahepatic origin of neutral ribonuclease has been investigated. After partial pancreatectomy, a significant decrease is observed in both plasma and liver neutral ribonuclease. The effect is specific, for it does not occur for other lysosomal enzymes. Also, labelled bovine pancreatic ribonuclease, when injected intravenously, is taken up by the liver. The sedimentable labelled enzyme has a density distribution similar to the distribution of other foreign proteins, horseradish peroxidase or yeast invertase. These results are explained by the uptake of plasmatic neutral ribonuclease from pancreatic origin by the liver.
DNA Synthesis in Circulating Erythroblasts of Anemic Duck
Authors: MODAK Sohan P. , COMMELIN Dominique , GROSSET Lise , MONNAT Marianne , IMAIZUMI Marie‐Thérése , SCHERRER Klaus 
Published: March 2005

In the circulating blood of anemic ducks, 5 % of all erythroid cells synthesize DNA. Immature erythroblasts, at all stages of differentiation, synthesize DNA although to a varying degree, while reticulocytes and erythrocytes do not. In the erythroid cell population labeled in vitro 2 h with 32Pi, half of the labeled DNA sediments as small‐molecular‐weight molecules, suggesting that these molecules fail to integrate into the high‐molecular‐weight components.Labeled DNA is found in the cytoplasmic postmitochondrial fractions and it is in a form of deoxyribonucleoproteins which cosediment with ribosomes as well as subribosomal particles in sucrose gradients. However, fixation with HCHO and centrifugation to equilibrium in CsC1 gradient of these particles shows that the deoxyribonucleoprotein bands at the density different than the ribosomes and, thus, not physically linked to them. In EDTA‐dissociated ribosomes, the deoxyribonucleoprotein particles cosediment with ribosomal subunits in such a way that the larger the particle, the larger the molecular weight of the DNA cosedimenting with it.The specific radioactivity of the cytoplasmic ribosome‐derived and postribosomal‐particle‐derived DNAs and the small molecular‐weight nuclear DNA is similar and 10‐20‐fold higher than that of the bulk nuclear DNA. The former three DNA species sediment between 4‐14 S. It is concluded that the cytoplasmic nonmitochondrial DNA species are of the nuclear origin. Less than 0.5% of the total cellular nonmitochondrial DNA can be purified from the nucleus and the cytoplasm as fast‐labeled small‐molecular‐weight components. All of the cellular nonmitochondrial DNA species band at the same mean buoyant density in Cs2SO4/urea gradients. All behave as native structures in hydroxyapatite and contain less than 5% of their length as single‐stranded regions.
Inhibition of Collagenase from Achromobacter iophagus by Synthetic Peptides
Authors: SVENSSON Birte , SIFFERT Odile , KEIL Borivoj 
Published: March 2005

Peptides of the general structure Pro‐Leu‐X‐Pro have been synthesized, with proline in l or d‐form and with either glycine or sarcosine in the position of X. Their inhibitory action on the cleavage of the peptide Cbz‐Gly‐Pro‐Leu‐Gly‐Pro by pure collagenase from Achromobacter iophagus was studied.Competitive inhibition was found in all cases, the most efficient by Pro‐Leu‐MeGly‐Pro. One product of cleavage of the synthetic substrate, Cbz‐Gly‐Pro‐Leu, also inhibits the enzyme.