bluuebunny/crossref_metadata_2025_split huggingface dataset:
Studies on the Environment of Protein S7 within the 30‐S Subunit of Escherichia coli Ribosomes
Authors: RINKS Jutta , YUKI Atsushi , BRIMACOMBE Richard 
Published: March 2005

Analyses are described of three types of ribosomal fragment, all derived from the well‐characterized ribonucleoprotein species consisting of proteins S7, S9, S 10, S14 and S19, together with RNA from sections O′‐D‐E′‐K‐P‐P′‐E‐A of the 16‐S sequence.

When 30‐S subunits were hydrolysed with ribonuclease T1 in the presence of deoxycholate in addition to the components previously described, a fragment could be isolated which contained only proteins S 7 and S19, together with minor amounts of S13 or S 14. Oligonucleotide analysis of this fragment showed that it contained RNA from sections O′‐E′ and P‐A of the 16‐S RNA, but that section K (from the middle of this area) was missing.
It has previously been shown that when 30‐S subunits are irradiated with ultraviolet light, protein S7 is the primary target of cross‐linking of protein to RNA. By making use of this reaction, ribonucleoprotein fragments were isolated from irradiated 30‐S subunits, the unbound proteins were removed, and RNA fragments containing covalently linked protein S7 were identified. It was possible to demonstrate that the site of cross‐linking lies within the O′‐A region of the 16‐S RNA, and more precise experiments showed that this site almost certainly is in the P‐A region.
When the parent five‐protein ribonucleoprotein fragment (above) was deproteinized under very mild conditions, RNA complexes could be isolated which consisted of non‐contiguous sequences, but which migrated as a single species into a polyacrylamide gel. Analysis of one of these complexes showed that it contained sequences from sections O′‐E′ and P‐A, but that section K was missing (cf. first paragraph above). This demonstrated that these two separate regions of RNA interact within the 30‐S subunit, independently of the presence of protein.
The Role of the Physical State of Lipopolysaccharides in the Interaction with Complement
Authors: GALANOS Chris , LÜDERITZ Otto 
Published: March 2005

Lipopolysaccharides interact with complement only when they are present in a state of high aggregation with a high apparent molecular weight. Lipopolysaccharides in uniform salt forms prepared by electrodialysis and neutralization with different bases exhibited distinct differences in their anticomplementary activity which correlated with differences in their sedimentation coefficients.Conversion of smooth (S) form lipopolysaccharides into the low‐molecular‐weight triethylamine form completely abolished their anti‐complementary activity while conversion into the highmolecular‐weight sodium form increased their activity. In contrast, a similar treatment of highly defective Re and Rd rough (R) form lipopolysaccharides had no effect on their ability to interact with complement. Both the triethylamine and sodium forms were strongly anti‐complementary despite large differences in their molecular weight. This was found to be due to the property of R lipopolysaccharides to reaggregate into a large‐molecular‐weight form through absorption of Mg2+ and Ca2+ present in the guinea pig serum used as complement source. Defective lipopolysaccharides derived from the Ra and Rb classes showed only negligible anti‐complementary activity which did not increase by conversion into salt forms with high molecular weight.
Calorimetric Study on Human Erythrocyte Glycolysis
Authors: MINAKAMI Shigeki , de VERDIER Carl‐Henric 
Published: March 2005

The heat production of human erythrocytes was measured on a flow microcalorimeter with simultaneous analyses of lactate and other metabolites. The heat production connected with the lactate formation was about 17 kcal (71 kJ) per mol lactate formed which corresponded to the sum of heat production due to the formation of lactate from glucose and the heat production due to neutralization.The heat production rate increased as the pH of the suspension increased, corresponding to the increase in lactate formation. Glycolytic inhibitors such as fluoride and monoiodoacetate caused a decrease in the rate of heat production, whereas arsenate induced a large transient increase in heat production associated with a transient increase in lactate formation. Decrease in pyruvate concentration was usually associated with increase in heat production, although the decreased pyruvate concentration was coupled with formation of 2,3‐bisphosphoglycerate.When inosine, dihydroxyacetone or d‐glyceraldehyde was used as a substrate, an increase in the heat production rate was observed. Addition of methylene blue caused an oxygen uptake which was accompanied by a remarkable increase in heat production rate corresponding to about 160 kcal (670 kJ) per mol oxygen consumed.The value for heat production in red cells in the above‐mentioned metabolic conditions was considered in relation to earlier known data on free energy and enthalpy changes of the different metabolic steps in the glycolytic pathway.
Unequivalence between Hemoglobin Subunits
Authors: CASSOLY Robert 
Published: March 2005

The effects of inositol hexakisphosphate on the visible absorption spectrum of liganded valency hybrids α2COβ2+H2O, α2+H20β2CO and α2COβ2+CN, α2+CNβ2co (where αCO, α+H2O, α+CN and βCO, β+H2O, β+CN represent the α and β chain of hemoglobin, respectively, in their carbon monoxide, aquomet and eyanomet forms) have been examined in an attempt to determine if their α and β chains are equally sensitive to the action of the anion.The difference spectra induced by inositol hexakisphosphate, are different for the two chains. The β+H2O subunit contributes chiefly to the absorbance changes, rather than α+H2O. In contrast, it is the αCO chain which is more sensitive to inositol hexakisphosphate than βCO. The question ofwhether such a selective response would also occur in aquomethemoglobin and carboxyhemoglobin is discussed. Criteria of changes in the quaternary structure of hybrids has been studied by measuring the effects of inositol hexakisphosphate on their ultraviolet absorption spectrum.
Isolation and Characterization of Iron‐Binding Proteins from Rat Intestinal Mucosa
Authors: HUEBERS Helmut , HUEBERS Eiko , RUMMEL Walter , CRICHTON Robert R. 
Published: March 2005

Two iron‐binding proteins were isolated from rat intestinal mucosa. From determination of their molecular weights, their electrophoretic and iron‐binding properties it was established that one was a mucosal ferritin and the other a mucosal transferrin. The mucosal ferritin is compared in its molecular weight, isoelectric point, amino acid composition and tryptic peptide pattern with the ferritins of rat spleen and liver. All three ferritins are distinctly different from one another. In addition the iron content of mucosal ferritin was found to be much lower than that of liver and spleen ferritins.Mucosal transferrin was separated into two components by isoelectric focusing, as was plasma transferrin. The plasma and mucosal transferrins differ in their isoelectric points and in their amino acid compositions. Differences were also found in vitro in the iron‐binding of mucosal transferrin as compared with plasma transferrin. The role of these mucosal proteins in the absorption of iron is briefly discussed.
Chemical Modification of the Tryptophan Residues of Wheat‐Germ Agglutinin
Authors: PRIVAT Jean‐Paul , LOTAN Reuben , BOUCHARD Philippe , SHARON Nathan , MONSIGNY Michel 
Published: March 2005

The oxidation of the tryptophan residues of wheat germ agglutinin by N‐bromosuccinimide was investigated under non‐denaturing and denaturing conditions. All three tryptophan residues present in wheat germ agglutinin subunit (molecular weight 18000) could be modified in 0.1 M acetic acid 8 M urea, pH 3.9. One of the residues failed, however, to react with N‐bromosuccinimide when the modifications in 0.1 M citrate buffer, pH 6.0.Tryptophan fluorescence of the protein was quenched concomitantly with the oxidation of two tryptophan residues even when the modification was carried out in acetic acid urea. After oxidation of two tryptophan residues per subunit of wheat germ agglutinin, only 15% of the original tryptophan fluorescence remained; upon excitation at 280 nm, tyrosine fluorescence entered at 305 rim could be resolved. The results suggest that there are only two emitters in the protein and that the third tryptophan residue is buried in the native protein and can be modified only in acetic acid urea. This tryptophan residue is quenched in the native protein.Saturation of wheat germ agglutinin with tri‐N‐acctylchitotriose did not protect the tryptophan residues from oxidation by N‐bromosuccinimide. Under these conditions, however, the reactivity of the tryptophan residues towards N‐bromosuccinimide was reduced and a higher concentration of' the reagent was required to achieve the same extent of oxidation as in the absence of the saccharide.Oxidation of one tryptophan residue per subunit in acetic acid urea led to almost complete loss (97%) of hemagglutinating activity, a 3.5‐fold decrease in the affinity constant for tri‐N‐acetylchitotriose and loss of ability of the subunits (s020.w.= 2.0S) to reassociate to the native dimer (s020.w= 3.5 S) after dialysis against a non‐denaturing buffer.No significant changes in the circular dichroism spectrum of wheat germ agglutinin were observed after oxidation of the three tryptophan residues, suggesting that no gross conformational changes occurred.The steric relationships between the fluorescent tryptophan residues of wheat germ agglutinin and saccharides are discussed.
Nanosecond‐Pulse Fluorimetry of Wheat‐Germ Agglutinin (Lectin)
Authors: PRIVAT Jean‐Paul , WAHL Philippe , MONSIGNY Michel , AUCHET Jean‐Claude 
Published: March 2005

Nanosecond‐pulse fluorimetry of wheat germ agglutinin is analyzed as a function of both excitation and emission wavelengths.When excited at 280 nm, wheat germ agglutinin fluorescence exhibited three lifetimes: one corresponding to the tyrosine residues as a whole and two others corresponding to the tryptophyl emission.The tyrosine contribution to the emission spectrum deduced from this method was in good agreement with that reported previously in steady‐state fluorescence experiments [Privat, J. P. and Monsigny. M. (1975) Eur. J. Biochem. 60, 555–567].The fluorescence decay of each tryptophan residue was not a single exponential function when wheat germ agglutinin was excited at 295 nm. This could he related to the microenvironment of the indole chromophores in the protein. The comparison of the quantum yield and of average lifetime showed that some tryptophan residues were completely quenched.Energy transfer from tyrosines to tryptophan residues previously detected in steady‐state fluorescence was also revealed by fluorescence decay measurements. Comparison of both methods showed that an important part of transfers occurred with a very fast rate equal to or greater than 1010s−1.Both lifetimes and the ratio of the short and the long‐lived component were found dependent on tri‐N‐acetylchitotriose binding.
The Metabolism of O‐Acyl‐N‐acylneuraminic Acids
Authors: CORFIELD Anthony P. , Clarice FERREORA DO AMARAL , WEMBER Margret , SCHAUER Roland 
Published: March 2005

The enzymic synthesis of 4‐O‐acetyl‐N‐acetylneuraminic acid, 4‐O‐acetyl‐N‐glycolylneuraminic acid, 4‐O‐glycolyl‐N‐acetylneuraminic acid, 9‐O‐acetyl‐N‐acetylneuraminic acid and 9‐O‐acetyl‐N‐glycolylneuraminic acid is shown using radioactive precursors with surviving slices, membrane fractions or particle‐free homogenates from bovine and equine submandibular glands.
Acetyl‐CoA: N‐acetylneuraminate‐9(or 7)‐O‐acetyltransferase activity was found in a microsome fraction and in the cytosol of bovine submandibular glands. The properties of the membrane‐bound enzyme acting on endogenous, glycoprotein‐bound N‐acetyl‐ and N‐glycolylneuraminic acids were compared with those of the soluble enzyme, O‐acetylating exogenous, non‐glycosidically bound N‐acetyl‐ and N‐glycolylneuraminic acids.
A rapid, radioactive assay for the membrane‐bound enzyme activity is described. The enzyme activity shows an optimum at pH 7 and has a Km for acetyl‐CoA of 0.1 mM. The enzyme is inhibited by p‐chloromercuribenzoate and iodoacetate. Divalent cations, EDTA and glutathione have no influence on its activity while CoA proved to be a competitive inhibitor with a K1 of 0.56 mM.
The soluble enzyme activity, assayed using a radioactive procedure, shows Km values of 0.01 mM, 0.5 mM and 0.39 mM for acetyl‐CoA, N‐acetylneuraminic acid and N‐glycolylneuraminic acid respectively. The general properties are similar to those found for the membrane‐bound enzyme, except that membrane‐bound activity is stable for longer on storage at 4 °C.
Acetyl‐CoA, acyl‐CoA and CoA concentrations of 33 nmol, 65 nmol and 106 nmol/g wet tissue respectively are found in fresh bovine submandibular glands.
The occurrence of the CMP‐glycosides of N‐acetylneuraminic acid, 9‐O‐acetyl‐N‐acetylneuraminic acid and N‐glycolylneuraminic acid in bovine submanibular glands is demonstrated.
The results are discussed in relation to the general metabolism of acylneuraminic acids.
The Effects of Temperature and Some Inhibitors an the Carnitine Exchange System of Heart Mitochondria
Authors: RAMSAY Rona R. , TUBBS Philip K. 
Published: March 2005

11‐Trimethylamino‐undecanoyl‐l‐carnitine (K; = 56 μM) and 6‐trimethylaminohexanoyl‐l‐carnitine (K1, = 1.3 mM) are competitive inhibitors of the ox heart mitochondrial carnitine exchange system. The latter is itself a poor substrate, with a V about 0.7 of that for carnitine. These compounds have been'used as ‘stop inhibitors’ in a study of the effect of temperature an the carnitine exchangc.
The carnitineout↔ H carnitinein exchange has a temperature coefficient (Q10) of 8.5 and an activation energy of 176 kJ/mol which is constant from 0 °‐18 °C. The Km for L‐carnitine (5.3 mM) is also constant over this temperature range.
The slow efflux (leak) of mitochondrial L.‐[14C]carnitine in the absence of external substrate has a similar temperature dependence and is also inhibited by 11‐trimethylamino‐undecanoyl‐L‐carnitine. lt is probably mediated by the same system as the very much Taster exchange with external carnitine
Purification and Characterization of Microsomal and Lysosomal β‐Glucuronidase from Rat Liver by Use of Immunoaffinity Chromatography
Authors: HIMENO Masaru , NISHIMURA Yukio , TSUJI Hiroshi , KATO Keitaro 
Published: March 2005

Rat liver β‐glucuronidase (EC 3.2.1.31), both from microsomal and lysosomal fractions, were pinked about 9500‐fold over the homogenate with high yield using affinity chromatography prepared by coupling purified specific immunoglobulin G against rat preputial gland β‐glucuronidase to Nepharose 2B and isoelectric focusing.The purified enzymes appeared homogeneous on electrophoresis in polyacrylamide gel and had a molecular weight of approximately 310000. In dodecylsulfate polyacrylamide gel electrophoresis, the microsomal β‐glucuronidase showed a single band corresponding to a molecular weight of 79000, while the lysosomal β‐glucuronidase had three distinct bands which consisted of one major and two minor bands corresponding to molecular weight of 79000, 74000, and 70000, respectively. A broad pH activity curve with a single optimum at pH 4.4 was observed in both the microsomal and the lysosomal β‐glucuronidases. Immunological gel diffusion technique with rabbit antiserum against rat liver lysosomal β‐glucuronidase revealed that the both enzymes had the same or quite similar antigenic determinants.
Serine Transhydroxymethylase from Rabbit Liver
Authors: BOSSA Francesco , BARRA Donatella , MARTINI Filippo , SCHIRCH La Verne , FASELLA Paolo 
Published: March 2005

The amino acid sequence of′ the coenzyme‐binding site of serine transhydroxymethylase from rabbit liver has been determined. After reduction with NaBi14 and aminoethylation, a first sample of enzyme was digested with thermolysin and a single phosphopyridoxyl peptide was isolated.A second sample of similarly treated enzyme was digested with chymotrypsin and three phosphopyridoxyl peptides clearly originating from a unique coenzyme‐binding site were isolated. Sequence analysis of these peptides indicate the following structure: Val‐Val‐Thr‐Thr‐Thr‐His‐Lys (Pxy) ‐Thr‐Leu. Sequence homologies of the active site of various pyridoxalphosphate enzymes are discussed in terms of a possible catalytic role and of evolution of this class of proteins.
A Study of Calf‐Thymus Histone H2B Using 13C Magnetic Resonance
Authors: TANCREDI Teodorico , TEMUSSI Piero A. , PAOLILLO Livio , TRIVELLONE Enrico , CRANE‐ROBINSON Colyn , BRADBURY E. Morton 
Published: March 2005

Calf thymus histone H2B has been studied by means of 13C magnetic resonance. Most sidechain resonances have been assigned. Analysis of 13C peak intensities by a simple computer‐aided method proves that 13C magnetic resonance spectroscopy can he used to monitor aggregation phenomena more accurately than 1H magnetic resonance or other physico‐chemical methods.Re‐examination of 1H spectral simulations shows substantial agreement with 13C results. It is concluded that in 0.1 M added NaCI the H2B aggregates include the chain segment from 50 (± 5)to 108 (± 5).
DNA Blockade by Rifampicin‐Inactivated Escherichia coli RNA Polymerase, and Its Amelioration by a Specific Mutation
Authors: HAYWARD Richard S. 
Published: March 2005

Partially diploid strains of Escherichia coli containing both rifampicin‐sensitive and rifampicin‐resistant RNA polymerase are, in general, sensitive to the drug: of the two copies of the rpoB gene present in such strains, that which codes for sensitive enzyme is dominant.
RNA polymerase purified from a normal sensitive strain of E. coli, and inactivated by rifampicin, can ‘blockade’ bacteriophage T7 DNA in vitro, inhibiting its transcription by drug‐resistant enzyme molecules.
A mutation, rcs‐40, reverses the normal dominance relationship in vivo, without detectably affecting the concentrations of resistant and sensitive RNA polymerase in the diploid cell. I show that rcs‐40 is closely linked to the rpoB gene which codes for the rifampicin‐sensitive enzyme.
Rifampicin‐sensitive RNA polymerase purified from E. coli rcs‐40, although indistinguishable from the normal enzyme by many criteria, is significantly less efficient in the production of drug‐dependent DNA blockade.
Studies on the Influence of Fatty Acids on Pyruvate Dehydrogenase Interconversion in Rat‐Liver Mitochondria
Authors: WALAJTYS‐RODE Elżbieta I. 
Published: March 2005

The effect of fatty acids on the interconversion of pyruvate dehydrogenase between its active (nonphosphorylated) and inactive (phosphorylated) forms was measured in rat liver mitochondria respiring in state 3 with pyruvate plus malate and 2‐oxoglutarate plus malate and during state 4 to state 3 transition in the presence of different substrates. The content of intramitochondrial adenine nucleotides was determined in the parallel experiments.
Decrease of the intramitochondrial ATP/ADP ratio with propionate and its increase with palmitoyl‐l‐carnitine in state 3 is accompanied by a shift of the steady‐state of the pyruvate dehydrogenase system towards the active or the inactive form, respectively.
Transition from the high energy state (state 4) to the active respiration (state 3) in mitochondria oxidizing 2‐oxoglutarate or palmitoyl‐l‐carnitine causes an increase of the amount of the active form of pyruvate dehydrogenase due to the decrease of ATP/ADP ratio in the matrix.
No change in ATP/ADP ratio can be observed in the presence of octanoate in mitochondria oxidizing pyruvate or 2‐oxoglutarate in state 3 or during state 4 to state 3 transition. Simultaneously, no significant change in phosphorylation state of pyruvate dehydrogenase occurs and a low amount of the enzyme in the active form is present with octanoate or octanoate plus 2‐oxoglutarate. Pyruvate abolishes this effect of octanoate and shifts the steady‐state of pyruvate dehydrogenase system towards the active form.
These results indicate that fatty acids influence the interconversion of pyruvate dehydrogenase mainly by changing intramitochondrial ATP/ADP ratio. However, the comparison of the steady‐state level of the pyruvate dehydrogenase system in the presence of different substrates in various metabolic conditions provides some evidence that accumulation of acetyl‐CoA and high level of NADH may promote the phosphorylation of pyruvate dehydrogenase.
Pyruvate exerts its protective effect against phosphorylation of pyruvate dehydrogenase in the presence of fatty acids of short, medium or long chain in a manner which depends on its concentration. It is suggested that in isolated mitochondria pyruvate counteracts the effect of acetyl‐CoA and NADH on pyruvate dehydrogenase kinase.
Synthesis of Stereospecifically Deuterated Phenylalanines and Determination of Their Configuration
Authors: BARTL Knut , CAVALAR Christiane , KREBS Traute , RIPP Engelbert , RÉTEY János , HULL William E. , GÜNTHER Helmut , SIMON Helmut 
Published: March 2005

Starting from trans‐cinnamic acid a chiral (−)3‐phenyl‐[2,3‐2H]propionic acid has been synthesized using Clostridium kluyveri cells as catalyst.
The chiral dideuterated acid has been converted by chemical methods to a mixture of (2R) and (2S)‐phenyl[2,3‐2H]‐alanine.
By means of 1H nuclear magnetic resonance spectroscopy and the action of D and L‐amino‐acid oxidase the configuration of the phenylalanine has been shown to be (2R, 3S) and (2S, 3S), respectively. The labelled phenylalanine is thus sterically and isotopically homogeneous at position 3 but heterogeneous at position 2.
The Euglena gracilis Chloroplast Genome:
Authors: KOPECKA Helena , CROUSE Edwin J. , STUTZ Erhard 
Published: March 2005

Chloroplast DNA was isolated from autotrophically and mixotrophically grown Euglena gracilis cells.
Aliquots of chloroplast DNA were mechanically degraded to an average molecular weight of 4–7 × 106 and G + C‐rich DNA fragments (density 1.701 g/cm3) were separated from the bulk DNA (density 1.685 g/cm3) using preparative CsCl density gradients.
Total chloroplast DNA and its DNA subfractions, which first were characterized with respect to average G + C content and hybridization capacity for chloroplast rRNA, were hydrolysed with restriction endonucleases (endo R. EcoRI, endo R. HindII, endo R. HindIII, endo R. HindII + III, endo R. HpaI, endo R. HpaII and endo R. HaeIII). The fragments were separated on gels under a variety of electrophoretic conditions.
With each enzyme tested, a rather large number of bands was obtained. In all cases, different banding patterns were obtained for total DNA, and the DNA subfractions.
Chloroplast DNA from autotrophically and mixotrophically grown cells gave identical banding patterns.
Digestion of total DNA with the endo R·HaeIII yielded 51–52 fragments separated in the gels in a total of 36 bands of which 11–12 bands were composed of 2–3 fragments as estimated by densitometry. The molecular weights of all fragments combined was 87 × 106 or 95% of the genome (92 × 106).
Chloroplast RNA hybridized to 5.1% with total chloroplast DNA, equal to three RNA cistrons per genome (Mr 92 × 106). These cistrons are located on seven different types of endo R. HaeIII fragments. The hybridising fragments are preferentially found in the G + C‐rich subfraction and in bands which are composed of 2–3 fragments.