bluuebunny/crossref_metadata_2025_split huggingface dataset:
Myeloperoxidase of Human Neutrophilic Granulocytes as Chlorinating Enzyme
Authors: Stelmaszyńsky Teresa , Zgliczyński Jan M. 
Published: March 2005

Two pH‐dependent spectral forms of myeloperoxidase have been described. Their absorption maxima in the Soret region were at 432 nm and 426 nm for acid and neutral pH, respectively. Chloride exerts an influence on the spectrum of peroxidase, mainly in acidic medium. Dissociation constants for the myeloperoxidase chloride complex and Km values for chloride in the chlorination reaction catalyzed by myeloperoxidase were determined. It was found that the affinity of chloride ions to the enzyme decreases with an increase of pH.Catalytic activity of myeloperoxidase in the reaction of incorporation of 36Cl into aliphatic amino compounds such as taurine, β‐alanine, ethanolamine and diethanolamine was investigated. Primary amino groups were chlorinated to N‐mono‐ or dichloramines, depending on the pH of the medium. The method of determination of 36Cl‐labelled chlorocompounds in the presence of excess Na36Cl was described.The role of myeloperoxidase as chlorinating enzyme in the mechanism of the bactericidal effect on bacteria phagocytized by neutrophilic granulocytes is discussed.
Reassociation and Reactivation of Lactic Dehydrogenase from the Unfolded Subunits
Authors: JAENICKE Rainer 
Published: March 2005

Lactic dehydrogenase from pig heart (H4) shows pH‐dependent reversible deactivation, denaturation and dissociation at pH < 6.The initial and final states in the dissociation‐association process are found to be the homogeneous fully inactive monomer (Mr= 37500 ± 1000) on one hand, and a heterogeneous mixture of denatured subunits, native tetramers and inactive higher aggregates on the other hand. The yield of tetramers and the extent to which renaturation occurs correspond to each other.Using optimum conditions of reactivation [pH 7.9, I∼ 0.2, 20 °C, in the presence of 1 mM dithiothreitol and 10 mM EDTA, enzyme concentration below 0.05 mg/ml], the correlation of reactivation and reassociation may be analyzed. The second‐order kinetics of the reactivation process prove reassociation to be the rate‐limiting step in the process of reactivation. From this one may conclude that in the case of the heart isoenzyme of lactic dehydrogenase the subunit does not represent the enzymatically active unit.The coenzyme (NAD+) increases the rate of reactivation but not the overall recovery. This suggests the coenzyme is involved in a nucleation step in the process of refolding and/or reassociation.
On the First Steps of Lactate Oxidation by Bakers' Yeast L‐(+)‐Lactate Dehydrogenase (Cytochrome b2
Authors: LEDERER Florence 
Published: March 2005

The behaviour of bakers' yeast l‐lactate dehydrogenase toward [2‐2H]lactate 3‐chlorolactate and 2‐hydroxy‐3‐butynoate is reported. By comparison with known facts concerning d‐amino acid and lactic oxidases, the following conclusions are drawn.1. Hydrogen removal at C‐2 is rate‐limiting in the overall reaction. This distinguishes l‐lactate dehydrogenase from the oxidases where it is product dissociation which limits the rate.2. The lack of dehydrohalogenation of 3‐chlorolactate by l‐lactate dehydrogenase, which differentiates the enzyme from the oxidases, can be explained if the reduction rate of flavin is much faster than for the oxidases.3. Although only indirect evidence is presented, it seems most probable that the lactate C‐2 hydrogen is removed as a proton, as in the case of d‐amino acid oxidase and lactic oxidase.4. The first steps of lactate oxidation are qualitatively similar for the two known enzymatically active forms of l‐lactate dehydrogenase.
The Determination of the Primary Structure of Histone F3 from Chicken Erythrocytes by Automatic Edman Degradation
Authors: BRANDT Wolf F. , VON HOLT Claus 
Published: March 2005

In order to determine the sequence of histone F3 by automatic Edman degradation, this protein was fragmented into a series of smaller fragments. Specific chemical cleavages rather than enzymatic degradations were applied in such a way as to yield a limited number of larger fragments.In the first step the histone F3 dimer was cleaved at the two methionine residues with cyanogen bromide. The three fragments were separated and purified by gel filtration. Their respective sizes were 90, 30 and 15 amino‐acid residues.The two larger fragments were both cleaved with N‐bromosuccinimide at tyrosine residues. They in turn yielded three and two fragments, respectively, which could be readily purified by gel filtration and carboxymethyl‐cellulose ion‐exchange chromatography.One of the larger fragments obtained by cleaving the 90 residue fragment at its tyrosine residues was further degraded by dilute acid into another three fragments and two free aspartic acid residues which also could be purified by gel filtration.The position of all the 10 fragments in the protein molecule became apparent by comparing the N‐ and C‐terminal amino‐acid residues of the starting material and the cleaved products after each cleavage.The simplicity of the peptide mixture after each cleavage resulted in an easy separation of the fragments.
Facilitation by Adenosine of the Action of Insulin on the Accumulation of Adenosine 3′:5′‐Monophosphate, Lipolysis, and Glucose Oxidation in Isolated Fat Cells
Authors: SCHWABE Ulrich , SCHÖNHÖFER Peter S. , EBERT Reinhold 
Published: March 2005

The modulation of insulin action by adenosine has been studied in lipid and glucose metabolism of isolated rat fat cells. When 20000 cells per ml were incubated, insulin failed to antagonize the effect of 1 μM noradrenaline on adenosine 3′:5′‐monophosphate (cyclic AMP) levels and lipolysis. At high concentrations (100000 cells per ml) both parameters were strongly depressed by insulin. The addition of 0.1 μM adenosine to dilute cell suspensions decreased cyclic AMP accumulation in response to noradrenaline, but only marginally reduced lipolysis, thus producing the same situation as seen in concentrated cell suspensions. Furthermore, insulin antagonized the cyclic AMP accumulation and lipolysis caused by adenosine deaminase (1 μg per ml) or theophylline (0.3 mM). These two agents only moderately elevated cyclic AMP levels similar to the effect of noradrenaline in the presence of adenosine. These data strongly indicate that insulin is able to counteract hormone effects on cyclic AMP formation and lipolysis only at low cellular levels of the cyclic nucleotide.Stimulation of glucose oxidation by insulin in the range between 10 and 100 μU per ml was markedly enhanced in the presence of 0.1 μM adenosine when only 5000 fat cells per ml were incubated. On the other hand, adenosine deaminase reduced the action of insulin in the range between 1 and 300 μU per ml in concentrated cell suspensions (100000 cells per ml). The uptake of adenosine and the ATP levels in fat cells were not altered by insulin, except at high concentrations of adenosine (0.1 mM). Theophylline (0.5 mM) and dipyridamole (20μM) abolished the stimulatory effect of both insulin and adenosine on glucose oxidation. Increasing concentrations of adenosine were able to overcome the inhibitory effect of theophylline but not that of dipyridamole. These data suggest that adenosine may have an essential regulatory role which can be described as facilitation of insulin actions, even though different mechanisms apply to lipolysis and glucose oxidation.
On the Mechanism of Ribonuclease A
Authors: SAENGER W. , SUCK D. , ECKSTEIN F. 
Published: March 2005

The triethylammonium salt of uridine 3′‐O‐thiophosphate methyl ester crystallized in space group P21 with cell dimensions a= 684.5 pm, b= 1480.4 pm, c= 2254.2 pm, β= 92.8° and two molecules per asymmetric unit. Solution of the structure was accomplished by direct methods; the nucleotide molecules have been located unambiguously but the cations are disordered and appear only as highly noise background. The least‐squares refinement converged at a conventional R‐factor of 19.1%.The base in both molecules of the asymmetric unit is anti with respect to the sugar, the conformation about the C(4′)‐C(5′) bond is gauche, gauche, the sugar pucker is C(2′)‐endo. The conformation about the two P–O ester bonds is not as observed in double helical RNA's, suggesting that the sulphur atom directs the orientation of the ester bonds.Uridine 3′‐O‐thiophosphate methyl ester was obtained by pancreatic ribonuclease A catalyzed methanolysis of the endo‐isomer of uridine 2′: 3′‐cyclothiophosphate. As the thiophosphate diester moiety is in the R configuration with respect to the methyl group, the enzyme must have attacked the cyclothiophosphate via an in‐line mechanism.
Hormonal Mechanisms Regulating Hepatic Steroid Metabolizing Activities
Authors: ERIKSSON Håkan 
Published: March 2005

The possible influence of androgens and estrogens on the sexual differentiation of hepatic enzymes metabolizing corticosterone was studied in the isolated perfused rat liver.The predominant metabolites in livers from normal male rats were 3β,11β,21‐trihydroxy‐5α‐pregnan‐20‐one, 5α‐pregnane‐3α,11β,20α, 21‐tetrol and 5α‐pregnane‐3β,11β,20β,21‐tetrol excreted as mono‐ and disulphates.Castration of adult male rats resulted in a reduced formation of 5α‐pregnane‐3,11β,20,21‐tetrols and a decreased ratio between 20β and 20α epimers. The amount of sulphate conjuged metabolites was increased.Partial hepatectomy of castrated adult male rats followed by complete regeneration of the liver parenchyma resulted in formation of 3α,11β,2 1‐trihydroxy‐5α‐pregnan‐20‐one.Administration of 100μg estradiol benzoate to normal adult male rats slightly reduced the amounts of 5αa‐pregnane‐3,11β,20,21‐tetrol epimers formed, whereas the same injection to castrated adult male rats markedly decreased the 20α (and 20β) oxidoreductase activity.The most pronounced effect of estradiol benzoate administration was seen in castrated adult male rats subjected to partial hepatectomy followed by complete parenchymal regeneration under estradiol influence. In these rats the metabolite profile was almost the same as that seen after perfusion of female rat livers with corticosterone. The predominant metabolite was 3αa,11β,15α,21‐tetrahydroxy‐5α,14ξ‐pregnan‐20‐one, which has never been found in the male rat. The activities of the 3‐ and 20‐hydroxysteroid oxidoreductases were almost the same as those found in livers from normal female rats. Furthermore, a major part of the metabolites were monosulphates which is typical of the female rat.The present data show that estrogens are capable of shifting conjugation and oxidoreductase activities in liver cells previously exposed to androgens towards a female pattern. However, an estrogen‐mediated induction of a 15‐hydroxylase active on corticosterone, which is a typical reaction in the female rat liver, can only take place in liver cells which have not previously been exposed to androgens.
Mössbauer Studies of Some Complexes of the Undecapeptide of Cytochrome c
Authors: BAUMGARTNER Celia P. , SELLERS Martha , NASSIF Rosemarie , MAY Leopold 
Published: March 2005

Complexes of cytochrome c and of an undecapeptide of the protein have been studied by means of Mössbauer spectroscopy in order to obtain information concerning the active heme site.The variation of the quadrupole splitting with the temperature permits an evaluation of the distortions from octahedral symmetry around the iron ion in the heme group, and also an estimation of the spin‐orbit constant. The effect of the different ligands such as CN−, F−, imidazol, etc., is discussed.
Enzymes of Nitrogen Metabolism in Legume Nodules
Authors: BOLAND Michael J. , BENNY A. Graeme 
Published: March 2005

An NADH‐dependent glutamate synthase has been purified 500‐fold from the plant cytoplasm fraction of Lupinus angustifolius nodules. It consists of a single polypeptide chain, Mr 235000. The optimum pH is 8.5, at which Km values for 2‐oxoglutarate, glutamine and NADH are 39 μM, 400 μM and 1.3 μM respectively. The catalytic centre activity is of the order of 70 s‐1 and is independent of pH between 6.5 and 9.5. Glutamate synthase is inhibited by glutamic acid, oxaloacetic acid. aspartic acid and asparagine, all competitive with 2‐oxoglutarate; and by NAD+, which is competitive with NADH.There is evidence of two flavine prosthetic groups per enzyme molecule.
Fructose Transport in Bacillus subtilis
Authors: GAY Philippe , DELOBBE André 
Published: March 2005

The transport of fructose in Bacillus subtilis was studied in various mutant strains lacking the following activities: ATP‐dependent fructokinase (fruC), the fructose 1‐phosphate kinase (fruB) the phosphofructokinase (pfk), the enzyme I of the phosphoenolpyruvate phosphotransferase system (the thermosensitive mutation ptsIl), and a transport activity (fruA). Combinations of these mutations indicated that the transport of fructose in Bacillus subtilis is tightly coupled to its phosphorylation either in fructose 1‐phosphate, identified in vivo and in vitro or in fructose 6‐phosphate identified by indirect lines of evidence. These steps of fructose metabolism were shown to depend on the activity of the enzyme I of the phosphoenolpyruvate phosphotransferase systems.The fruA mutations affect the transport of fructose when the bacteria are submitted to catabolite repression. The mutations were localized on the chromosome of Bacillus subtilis in a cluster including the fruB gene. When grown in a medium supplemented by a mixture of potassium glutamate and succinate the fruA mutants are able to carry on the two vectorial metabolisms generating fructose 6‐phosphate as well as fructose 1‐phosphate. A negative search of strictly negative transport mutants in fruA strains indicated that more than two structural genes are involved in the transport of fructose.
Lipopolysaccharides d'une Souche à Virulence Atténuée de Yersinia pestis
Authors: BORDET Claudette , BRUNETEAU Maud , MICHEL Georges 
Published: March 2005

Lipopolysaccharides from a Slightly virulent strain of Yersinia pestis were investigated. Two types of lipopolysaccharides were obtained from the bacteria: lipopolysaccharide I was extracted with aqueous phenol/chloroform/hexane while lipopolysaccharide II was extracted with phenol/water. Chemical analysis of these lipopolysaccharides shows the presence of D‐glucose, galactose, glucosamine, L‐glycero, ‐D‐manno‐heptose, D‐glycero‐D‐manno‐heptose, 3‐deoxyoctulosonic acid, phosphate, 3‐hydroxymyristic acid, and small quantities of palmitic acid and palmitoleic acid. In addition, lipopolysaccharide II contains arabinose.Lipopolysaccharides I and II were methylated; analysis by gas‐liquid chromatography and by mass spectrometry indicated the presence of 2,3,4,6‐tetra‐O‐methyl glucose, 2,3,4,6‐tetra‐O‐methyl galactose and of tri‐, tetra‐ and penta‐methylated heptose derivatives. Arabinose in lipopolysaccharide II was not methylated and is therefore entirely substituted, while glucose and galactose are not substituted. Sodium metaperiodate nearly entirely oxidized glucose and galactose. Part of the heptose was not degraded by periodate oxidation, while part was converted into mannose.Lipopolysaccharides I and II could be the R and S forms of the lipopolysaccharide respectively, the S form containing an O‐specific chain with arabinose.The lipopolysaccharides were hydrolysed with acetic acid and degraded polysaccharides I and II were obtained. A large part of the arabinose was lost during the hydrolysis of lipopolysaccharide II into polysaccharide II, thus indicating that the arabinose might be in the furanose form.The absence of phosphate groups in polysaccharides I and II suggests the absence of bridges between the chains. However, if such bridges exist in the lipopolysaccharides, they are either on 3‐deoxyoctulosonic acid or on lipid A.
Biochemical Markers of the Progress of Differentiation in Cloned Teratocarcinoma Cell Lines
Authors: ADAMSON Eileen D. , EVANS Martin J. , MAGRANE Gregg G. 
Published: March 2005

The progeny of single teratocarcinoma cells will give rise to several different cell types in vitro, and the latter were shown to be functionally differentiated by biochemical criteria. In these studies, cloned lines of mouse teratocarcinoma cells were assayed during the course of differentiation for some biochemical products characteristic of the tissues formed. The carcinoembryonic protein, α‐foetoprotein was not synthesized by undifferentiated embryonal carcinoma (EC) cells, but was synthesized in increasing amounts during their differentiation to endoderm‐type cells in suspension culture. α‐Foetoprotein was shown to be a product of endoderm cells, but not all endoderm cells synthesized this protein.During the course of further differentiation when EC cells or aggregates were grown in tissue‐culture dishes, other biochemical products appeared. In cultures containing predominantly nerve‐type cells, there was a 30‐fold increase in the specific activity of acetylcholinesterase, with concomitant appearance of the aldolase isoenzyme characteristic of mouse brain. In some cultures, a small amount of muscle‐type cell formation was marked by the appearance of the MB isoenzyme of creating phosphokinase. Generally, biochemical differentiation was immature.
The Low‐Spin ⇌ High‐Spin Transition of Camphor‐Bound Cytochrome P‐450
Authors: LANGE Reinhard , BONFILS Claude , DEBEY Pascale 
Published: March 2005

The spin state of camphor‐bound cytochrome P‐450 is shown to depend largely on medium and temperature in aqueous as well as in mixed organic buffer. At sub‐zero temperatures a variation of paH, ionic strength or camphor concentration modifies the spin equilibrium from nearly pure high‐spin form to nearly pure low‐spin form. Since the apparent pKa of transition is a linear function of log I, the spin state seems to be controlled by the electrostatic potential in the heme proximity. K+ is found to have a specific effect on the spin state.The change of enthalpy, ΔH values, of the spin transition depends on the same parameters as the equilibrium constant, in the organic cosolvent as well as in aqueous buffer. As the cosolvent effect is reflected by higher ΔH values, and KCI and pH tend to lower ΔH, the cosolvent effect can easily be compensated. Therefore kinetic studies of the spin conversion might well be undertaken at sub‐zero temperature in this solvent.
Endonucleolytic Cleavage of Parental DNA and T4 Late‐Gene Expression: Distribution Analysis of Single‐Strand and Double‐Strand Breaks
Authors: GROSSI Gianfranco , MACCHIATO Maria , GIALANELLA Giancarlo , CASCINO Antonino 
Published: March 2005

In order to investigate the dependency of late transcription on concurrent DNA replication during bacteriophage T4 development, we analyzed the endonucleolytic cleavage kinetics of the DNA of a T4 mutant lacking DNA polymerase, DNA ligase and exonuclease by using the sucrose gradient sedimentation technique. Our results can be summarized as follows.1. The single‐strand endonucleolytic cleavage of the T4 mutant DNA is not a random process.2. The number of single‐strand nicks reaches a plateau level of 10–12 nicks/molecule.3. The occurrence of a double‐strand break is delayed and their number is at any time lower than the number of single‐strand nicks.4. The circular permutation of T4 genome, as computer‐simulated by the Monte Carlo method, produces a smoothing of the discrete distribution which would be expected if nicks were localized in the promoter sites of late transcription units.We conclude that our findings support the model which relates single‐strand DNA nicks to the late transcription initiation sites.
Synthesis of Transfer RNA during the Synchronous Nuclear Division Cycle in Physarum polycephalum
Authors: FINK Kirsten , TURNOCK Geoffrey 
Published: March 2005

1. The synthesis of tRNA during the synchronous nuclear division cycle in plasmodia of Physarum polycephalum has been investigated using an isotope dilution procedure and compared to the pattern of synthesis of rRNA.2. The synthesis of both tRNA and rRNA stops during mitosis. As the genes for the two types of RNA are not linked, this finding suggests that cessation of synthesis during nuclear division is a common characteristic of all types of transcription, supporting earlier work using pulse labelling and autoradiography to investigate the same problem.
Immunological Studies on Beef‐Heart Ubiquinol — Cytochrome c Reductase (Complex III)
Authors: NELSON B. Dean , MENDEL‐HARTVIG Ib 
Published: March 2005

Antibodies against isolated beef‐heart ubiquinol – cytochrome c reductase (complex III) have been characterized. Antibodies to complex III react strongly with isolated beef heart complex III and intact beef heart mitochondria, as shown by immunodiffusion and rocket electrophoresis experiments. The complex III content of intact mitochondria can be quantitated with rocket electrophoresis using isolated complex III as a standard. Antibodies to complex III also react with beef liver mitochondria and with both heart and liver mitochondria from rats. The latter are very weak antigens compared to beef heart material. Antibodies to complex III do not react with respiratory chain complexes I and IV, or F1‐ATPase from beef heart mitochondria, but gives a slight, but variable, reaction with complex II and the membrane fraction isolated from complex V (oligomycin‐sensitive ATPase). Antigenic sites are located on at least five of the seven peptides of complex III. These peptides are presumably lacking in respiratory chain complexes which do not react with antibodies to complex III, and are assumed to be uniquely located in complex III.Antiserum against complex III inhibits duroquinol–cytochrome c reductase activity in isolated complex III and in complex III incorporated into phospholipid vesicles. Oxidation of NADH and succinate is not affected in submitochondrial particles treated with 6‐times more antibody than required for complete inhibition of enzyme activity in free complex III or in complex III‐phospholipid vesicles.
The Purification, Characterization and Localization of a Parvalbumin‐Like Protein from Chicken‐Leg Muscle
Authors: HEIZMANN Claus W. , HÄUPTLE Marie‐Theresè , EPPENBERGER Hans M. 
Published: March 2005

A parvalbumin‐like protein was purified to homogeneity from chicken leg muscle, 40 mg of protein was isolated from 1 kg muscle which is 20% of the amount obtained for parvalbumin isolated from rabbit muscle by a similar procedure. The protein contained 1–2 residues of tyrosine and 1 residue of tryptophan, three arginine residues and a rather small number (4–5) of phenylalanine residues. The differences in the aromatic amino acid content account for the less distinct vibronic structure in the ultraviolet region below 275 nm compared to most other parvalbumins. The protein contained <0.04 residue of γ‐carboxyglutamic acid per molecule. However, the molecular weight of 12000, high content of glutamic acid and aspartic acid, the low content of proline and histidine, and the presence of two calcium atoms per molecule were properties common to parvalbumins. Immunprecipitation experiments in agar using anti‐chicken parvalbumin‐like protein indicated that an immunologically indistinguishable form of this protein is present in heart, white and red back muscles, breast, stomach, brain, pancreas, small intestine and kidney, but not in spleen, liver and blood.The distribution is therefore as ubiquitous as G‐actin or β‐actinin. Parvalbumin‐like protein was found to accumulate in differentiating primary muscle cell cultures after 120 h. This approximates to the time on which myosin and actin start to accumulate, proteins necessary for myofibril assembly.Experiments to investigate the localization of parvalbumin‐like protein, using the indirect immunofluorescence technique showed regular cross‐striation patterns within the I band of isolated myofibrils.The results suggest that parvalbumin‐like protein may interact with one or more of the protein components of the thin filament thus being involved in the contractile process. This component could be β‐actinin which copurified with parvalbumin‐like protein through the DEAE‐cellulose step (see following paper).