bluuebunny/crossref_metadata_2025_split huggingface dataset:
The Lipoxygenase of Reticulocytes
Authors: RAPOPORT Samuel M. , SCHEWE Tankred , WIESNER Rainer , HALANGK Walther , LUDWIG Peter , JANICKE‐HÖHNE Marina , TANNERT Christof , HIEBSCH Christa , KLATT Dietmar 
Published: March 2005

A lipoxygenase has been purified from rabbit reticulocyte‐rich anaemic blood cells. It possesses a molecular weight of 78000 and an isoelectric point of 5.5 and contains 5% neutral sugars and two iron atoms per enzyme molecule. The lipoxygenase has proved to be identical with the inhibitors of respiratory proteins described formerly.The actions of the lipoxygenase on linoleic acid, phospholipids, mitochondrial and erythrocyte membranes and electron transfer particles were studied. A special feature of the reticulocyte lipoxygenase is the suicidal character of its action on lipids. With electron transfer particles the reticulocyte lipoxygenase causes a loss of acid‐labile sulfur which accompanies respiratory inhibition; the strong respiratory inhibition is not exerted by soybean lipoxygenase. The reticulocyte lipoxygenase acts preferably on mitochondrial membranes as compared with cell membranes of the erythrocyte; erythrocyte cytosol moderates the action on mitochondrial membranes. Furthermore, the lipoxygenase reaction can concomitantly and irreversibly inactivate sulfhydryl enzymes as demonstrated with muscle glyceraldehyde‐3‐phosphate dehydrogenase. The occurrence of the lipoxygenase here described is restricted to reticulocytes; very low amounts were observed in bone marrow and no lipoxygenase was detectable in normal blood. During the course of an experimental anaemia the lipoxygenase is produced owing to superinduction in large amounts, which may persist for a long time since they escape inactivation.Preliminary evidence was obtained for the occurrence of other lipoxygenases in tissues of lung, spleen, kidney and also epithelial tumours
DNA‐Dependent RNA Polymerase from the Archaebacterium Sulfolobus acidocaldarius
Authors: ZILLIG Wolfram , STETTER Karl O. , JANEKOVIĆ Davorin 
Published: March 2005

Purified DNA‐dependent RNA polymerase from Sulfolobus acidocaldarius is composed of 10 different subunits, one of which is present as four copies. Their molecular weights are 122000, 101000, 44000, 32000, 24000, 17500, 13800, 11800 (four copies), 11200, 10800, summing up to a total Mr of 423500. The sedimentation velocity is 13.5 S, indicating that at 0.5 M NH4Cl the enzyme exists in the monomeric form. At pH 9.2 in cellogel electrophoresis two of the subunits migrate towards the cathode. The composition is quite different from that of a typical eubacterial RNA polymerase. Its complexity reminds one of eucaryotic RNA polymerase.Maximal transcription of DNA from a Halobacterium halobium phage φH (φH DNA) proceeds at pH 8.5 and 75 °C. The enzyme is stable up to 75 °C and strictly requires a DNA template. φH DNA and poly[d(A‐T) · d(A‐T)] are the most efficient. The temperature dependence of the transcription rate is characteristic for the template. Actinomycin D and heparin prevent transcription, while rifampicin, streptolydigin and α‐amanitin have no effect.During storage, even at −70°C, the enzyme loses its activity to transcribe φH DNA, whereas transcription of poly[d(A‐T) · d(A‐T)] remains unaffected.
Purification, Characterization and Localization of Serine Protease of Morris Hepatoma 8999
Authors: BANNO Yoshiko , MORRIS Harold P. , KATUNUMA Nobuhiko 
Published: March 2005

A serine protease of hepatoma 8999, isolated in the mitochondrial fraction, was purified and crystallized. The purified enzyme was apparently homogeneous on ultracentrifugal analysis and polyacrylamide disc gel electrophoresis. The ratio of absorbance at 280 nm and 260 nm, A280/A260, was 1.90 and its absorption coefficient, A1%280 was 10.5 cm−1 estimated from dry weight measurements. Its s20, w, value was 2.23 S and its molecular weight was estimated to be 24000 ± 1000. The enzyme contained twice as much lysine, arginine and histidine as chymotrypsinogen did, but had a very similar amino acid composition to serine protease from skeletal muscle. Its isoelectric point was pH 10.6.
The substrate specificity of the enzyme was the same as that of chymotrypsin A. Its Km, and kcat, values for N‐acetyl‐l‐tyrosine ethyl ester, N‐acetyl‐l‐phenylalanine ethyl ester and N‐acetyl‐l‐tryptophan ethyl ester were 0.35 mM and 10.69 s−1, 0.38 mM and 10.7 s−1, and 0.11 mM and 11.8 s−1, respectively. Its activity was completely inhibited by phenylmethylsulfonyl fluoride and partially inhibited with tosylphenylalanine chloromethyl ketone.
The enzyme was shown to be located in different granules from the intracellular particules (light and heavy mitochondrial fraction) by sucrose density gradient centrifugation, and it was stained in mast cells of the hepatoma 8999 by the immunofluorescent technique.
Serine protease is present in different amounts in various organs of rat and the enzyme from hepatoma 8999 gave a single band that fused completely with those of the enzymes from skeletal muscle, heart, liver and kidney, respectively, on Ouchterlony double‐diffusion analysis using antiserum to the crystalline enzyme of hepatoma 8999, but the enzyme from small intestine did not react with the antiserum.
Oligosaccharide and Ganglioside Neuraminidase Activities of Mucolipidosis I (Sialidosis) and Mucolipidosis II (I‐Cell Disease) Fibroblasts
Authors: CANTZ Michael , MESSER Helgdrd 
Published: March 2005

Fibroblasts cultured from the skin of patients with the genetic diseases mucolipidosis I and mucolipidosis II were found deficient in a neuraminidase specific for both an α2→3 and and α2→ 6 type of neuraminosyl linkage of sialyl oligosaccharides. Obligate heterozygotes (parents) showed an intermediate activity in mucolipidosis I, but a normal one in mucolipidosis II.The neuraminidase activity of mucolipidosis I fibroblasts towards gangliosides, measured at pH 4.5 in the presence of Triton X‐100, was within the range of normal controls with gangliosides Gm3 and GD3, but somewhat diminished with a bovine brain ganglioside preparation. In mucolipidosis II, neuraminidase activity was markedly decreased towards the bovine brain and Gm3 ganglioside substrates, and partially deficient with ganglioside GD3.The results suggest that in mucolipidosis I the degradation of glycoprotein‐derived sialyl oligosaccharides is impaired due to the genetic deficiency of an oligosaccharide neuraminidase, whereas the ganglioside catabolism is unaffected.The simultaneous decrease of both oligosaccharide and ganglioside neuraminidase activities in mucolipidosis II fibroblasts is considered to be another example of the multiple lysosomal hydrolase deficiency observed by others in these cells.Our data also suggest that the α2→3 and α2→6 oligosaccharide neuraminidase activities are genetically related, yet that they are distinct from the activities towards gangliosides possessing an α2→3 (GM3) or an α2→8 (GD3) terminal neuraminosyl linkage.
Metabolic Carbohydrate‐Labelling of Glycolipids from Mouse Splenocytes
Authors: ROSENFELDER Günter , VAN EIJK Ronald V. W. , MÜHLRADT Peter F. 
Published: March 2005

Splenic lymphocytes from CBA/J, AKR/A/J, BALB/c/A, C57/BL/6J, C3H/HeJ and C3H/Tif nu/nu mice and B lymphocyte or T lymphocyte preparations derived from CBA/J mouse spleen were cultivated in the presence of either concanavalin A, phytohemagglutinin, Salmonella minnesotaR595 lipopolysaccharide or Proteus mirabilis soluble lipoprotein. The mitogens stimulated the incorporation of [14C]galactose into acid‐insoluble cell material with the same specificity for B or T cells as that known for thymidine incorporation.The glycolipids extracted from mitogen‐activated, carbohydrate‐labelled B or T cells were compared by thin‐layer chromatography and characteristic differences between B and T cells were noted in the ganglioside as well as in the neutral glycolipid fractions. In addition, subsets of B or T cells, namely lipopolysaccharide‐responsive or lipoprotein‐responsive B‐cell populations or nylon‐purified T cells may be recognized by characteristic neutral glycolipid bands.
The Hormonal Control of Glycogen Metabolism
Authors: FOULKES J. Gordon , COHEN Philip 
Published: March 2005

Inhibitor‐1 has been shown to be phosphorylated in skeletal muscle in vivo. In normal fed animals the degree of phosphorylation was 31 ± 7% and this value increases to 70 ± 12% following an intravenous injection of adrenaline.The results imply that the phosphorylation of inhibitor‐1 may be equally as important as the phosphorylation of phosphorylase kinase in elevating the levels of phosphorylase a. The role of inhibitor‐1 in metabolism is discussed.
Porcine Pancreatic Lipase
Authors: BIANCHETTA Josiane D. , BIDAUD Jacqueline , GUIDONI Andréa A. , BONICEL Jacques J. , ROVERY Mireille 
Published: March 2005

The single polypeptide chain of about 460 amino acids of porcine pancreatic lipase (EC 3.1.1.3) has been fragmented into five peptides by cyanogen bromide cleavage [Rovery, M., Bianchetta, J. & Guidoni, A. (1973) Biochim. Biophys. Acta, 328, 391–395]. The sequence of the first three cyanogen bromide peptides (CNI, CNII, CNIII), including a total of 234 amino acids, was fully elucidated. Automatic or manual Edman degradation was performed on the different peptides. Fragmentations of the CN peptides were accomplished by digestions with trypsin (after citraconylation or 1,2‐cyclohexanedione treatment), chymotrypsin and Staphylococcus aureus external protease. Hydrolysis of unreduced material by pepsin and thermolysin, performed in order to determine the S‐S bridge positions, provided useful overlapping peptides.The glycan moiety of lipase is bound to Asn‐166. The non‐essential tyrosine specifically blocked by diisopropylphosphorofluoridate is Tyr‐49 in a cluster of asparagine and glutamine residues. The existence of a highly hydrophobic sequence (206–217) at the C terminus of the CNII fragment is noteworthy.
Dissociation and Aggregation of Lactic Dehydrogenase by High Hydrostatic Pressure
Authors: SCHMID Gerhard , LÜDEMANN Hans‐Dietrich , JAENICKE Rainer 
Published: March 2005

As shown by earlier experiments high hydrostatic pressure affects the catalytic function of lactic dehydrogenase from rabbit muscle. In the presence of substrates denaturation occurs, whereas in the absence of substrates and −SH‐protecting reagents oxidation of sulfhydryl groups takes place [Schmid, G., Lüdemann, H.‐D. & Jaenicke, R. (1975) Biophys. Chem. 3, 90–98; (1978) Eur. J. Biochem. 86, 219–224]. Avoiding oxidation effects by reducing conditions in the solvent medium and by chelation of heavy metal ions, the remaining high‐pressure effects consist of dissociation of the native quaternary structure into subunits followed by aggregation. Both reactions are influenced by temperature and enzyme concentration. Short incubation (≤ 10 min) at pH 6.0–8.5 and pressures of 0.3–1.0 kbar causes dissociation which is reversed at normal pressure. At 5°C the activation volume is found to be ΔV≠=–62 ± 3 cm3· mol−1. Above 1.2 kbar irreversible aggregation takes place; the reaction is favoured by low temperature and decreased pH. The activation volume for the aggregation process at 5°C is ΔV≠=–97 ± 3 cm3· mol−1.The results may be described by a reaction sequence comprising pressure‐induced dissociation of the native enzyme into its subunits followed by subunit aggregation to form inactive high‐molecular‐weight particles.
Purification of Rat‐Liver Microsomal UDP‐glucuronyltransferase
Authors: BOCK Karl Walter , JOSTING Dorothee , LILIENBLUM Werner , PFEIL Hugo 
Published: March 2005

Glucuronidation reactions catalysed by rat liver microsomal UDP‐glucuronyltransferase are differentially inducible by 3‐methylcholanthrene and phenobarbital. To elucidate the molecular basis of this functional heterogeneity the enzyme was purified from livers of rats pretreated with the inducing agents.Using cholate solubilization, chromatography on Bio‐Gel A‐1.5m and on DEAE‐cellulose in the presence of the nonionic detergent Brij 58, two enzyme forms could be separated. Both forms were subsequently purified to apparent homogeneity by affinity chromatography on UDP‐hexanolamine Sepharose 4B. 3‐Methylcholanthrene‐inducible enzyme activity towards 1‐naphthol, 4‐nitrophenol, 3‐hydroxybenzo(a)pyrene and N‐hydroxy‐2‐naphthylamine copurified with one enzyme form (enzyme 1). In contrast phenobarbital‐inducible enzyme activity towards morphine, chloramphenicol and 4‐hydroxybiphenyl was associated with the other enzyme fraction (enzyme 2). Sodium dodecylsulfate/polyacrylamide gels showed similar molecular weights of 54000 for enzyme 1 and 56000 for enzyme 2.The results suggest the presence of at least two forms of UDP‐glucuronyltransferase in rat liver. Factors affecting enzyme activity in purified and membrane‐bound states are discussed.
The Use of Equilibrium Density‐Gradient Ultracentrifugation in the Isolation and Characterisation of Glycoproteins with Blood Group P1 Activity from Sheep Hydatid‐Cyst Fluid
Authors: COSSEY Ailsa , DIMICHIEL Anthony , DUNSTONE John 
Published: March 2005

Equilibrium density‐gradient ultracentrifugation in caesium choride and caesium sulphate has been used in the isolation and fractionation of the glycoproteins specific for blood‐group P1 from hydatid cyst fluids. The fractions obtained have distinct and systematic differences specifically related to their buoyant densities, chemical compositions and specific‐activities for group P1.High levels of specific‐activity were maintained over a large range of chemical compositions. The peptide content varied systematically from 2.5% for the densest fraction to 37% for the least dense fraction. The amino acid composition was essentially constant over all fractions. The proportion of glucosamine decreased and the proportions of galactosamine, mannose and glucose increased with increasing peptide content of the fractions. The data presented suggest the presence of oligosaccharide side‐chains of various lengths and compositions and/or the presence of oligosaccharide side‐chains with very different chemical compositions, of which only some are associated with the specificity for group P1.The properties of the glycoproteins from hydatid cyst fluids have been compared with those of the glycoproteins from human ovarian cysts. Although some similarities have been demonstrated there are significant differences.
Occurrence of 3‐Oxo‐acyl Groups in the 6,6′‐Diesters of α‐d‐Trehalose
Authors: PUZO Germain , TISSIÉ Gérard , AURELLE Hélène , LACAVE Charlotte , PROMÉ Jean‐Claude 
Published: March 2005

The ‘cord factor’ from Corynebacterium diphtheriae was fractionated by thin‐layer chromatography of the trimethylsilyl derivatives into three main components: the true ‘cord factor’ B1 which has been described previously and two compounds, B2 and B3, containing 3‐Oxo‐acyl esters. These products were analyzed by mass spectrometry (field desorption/cationization and electron impact of the trimethylsilyl derivatives) and by chemical degradation.Compound B3 is a 6,6′‐bis(3‐oxo‐acyl)‐α‐d‐trehalose. The 3‐oxo‐acyl groups are mainly saturated species, branched at C‐2, containing 24, 26, 28, 30 or 32 carbon atoms. The main component of B3 is the 6,6′‐bis(3‐oxo‐2‐tetradecyl‐octadecanoyl)‐α‐d‐trehalose.Compound B2 is a 6,6′‐mixed ester of α‐d‐trehalose with the preceding 3‐oxo acids and with corynomycolic acids. These latter contain an even number of carbon atoms from 24 to 32 and are a mixture of saturated, mono‐unsaturated and di‐unsaturated species. The main compound of B2 is 6‐(3‐oxo‐2‐tetradecyl‐octadecanoyl)‐6′‐(3‐hydroxy‐2‐tetradecyl‐octadecanoyl)‐α‐d‐trehalose.The metabolic implications of this structural study, together with results already published, suggest that condensation of the common fatty acids by a Claisen‐like process via the oxo ester pathway may not be the only way for the synthesis of corynomycolic acids.
Catalytic Activity of Aspartate Aminotransferase in the Crystal
Authors: MOZZARELLI Andrea , OTTONELLO Simone , ROSSI Gian Luigi , FASELLA Paolo 
Published: March 2005

Natural substrates and analogs rapidly diffuse through crystals of pig heart mitochondrial aspartate aminotransferase and react at the active sites causing spectral changes that can be measured by single‐crystal microspectrophotometry. Dissociation constants for natural substrates and rate constants of transamination for slowly reacting substrates have been determined.A comparison between the data obtained in the crystal and in solution shows that the crystalline enzyme is catalytically competent and that events occurring in the crystal essentially parallel those occurring in solution, even though minor differences have been detected.
The Role of Chloroplast‐Membrane‐Protein Synthesis in the Circadian Clock
Authors: LEONG Ta‐Yan , SCHWEIGER Hans‐Georg 
Published: March 2005

A polypeptide (polypeptide P39), which is presumed to be involved in the photosynthetic circadian rhythm in the green alga Acetabularia, was purified from the EDTA‐insoluble chloroplast membrane fraction by means of preparative dodecylsulfate gel electrophoresis and then partially characterized.The purity of the isolated polypeptide P39 was confirmed by a further electrophoresis on an analytical dodecylsulfate gel and further elucidated by amino‐terminal analysis which shows that glycine is the only amino‐terminal amino acid of the purified polypeptide material. The molecular weight of the polypeptide P39 was found to be about 39000 on analytical gel electrophoresis and the value was further supported by those obtained from amino acid composition and peptide mapping.The amino acid composition of polypeptide P39 showed that the proportion of intermediate amino acid groups is high while the proportion of hydrophilic amino acid groups is well balanced by that of hydrophobic amino acid groups, a property characteristic of membrane proteins.
Studies on the Methylation of Cytoplasmic Ribosomal RNA from Cultured Higher Plant Cells
Authors: CECCHINI Jean‐Pierre , MIASSOD Raymond 
Published: March 2005

The methylation of cytoplasmic ribosomal RNA of cultured sycamore cells (Acer pseudoplatanus L.) was investigated. Labelled 17‐S and 26‐S rRNA were prepared from cells that had been incubated with either [32P]phosphate, [Me‐3H]methionine or [Me‐14C]methionine. Ion‐exchange resin chromatography of 0.3 M KOH or 1 M HCl hydrolysates and two‐dimensional chromatographic analyses of phosphodiesterase plus phosphatase digests of 17‐S and 26‐S rRNA were performed.17‐S and 26‐S rRNA contain 49 and 91 methyl groups per molecule, respectively. These values were verified in several ways. The high degree of methylation of sycamore rRNA, particularly for the 26‐S rRNA, contrasts with the situation in all other investigated organisms.Several methylated bases were identified. 7‐Methylguanine and 5‐methylcytosine both occur in 17‐S and 26‐S rRNA. N6‐Methyladenine and N6,N6‐dimethyladenine are restricted to the 17‐S rRNA while 3‐methyluracil and 1‐methyladenine occur in the 26‐S rRNA. One hypermodified uridine was also tentatively identified in the small rRNA. In 17‐S rRNA, there is one copy of 7‐methylguanine, N6‐methyladenine and hypermodified uridine and two copies of N6,N6‐dimethyl‐adenine. 3‐Methyluracil, 1‐methyladenine and 5‐methylcytosine occur twice, twice and three times, respectively, in 26‐S rRNA. 7‐Methylguanine and 5‐methylcytosine are only in submolar amounts in the 26‐S and 17‐S rRNA, respectively.There are 40 ± 2 and 83 ± 3 2′‐O‐methylriboses per 17‐S and 26‐S rRNA molecule, respectively. In addition to the four 2′‐O‐methylnucleosides, one 2′‐O‐methylpseudouridine is present in the 17‐S rRNA. Several lines of evidence argue for a non‐random distribution of the methylriboses. In particular, one and seven Nm‐Nm‐Np structures occur in the 17‐S and 26‐S rRNA, respectively.The data are discussed comparatively with the methylation pattern of Escherichia coli, yeast and HeLa cell rRNA.
Increased Biosynthesis of CoA in the Liver of Rats Treated with Clofibrate
Authors: SKREDE Sverre , HALVORSEN Ola 
Published: March 2005

The amounts of CoA in rat liver increased about three fold after treatment with clofibrate. About 10 of total CoA were long‐chain acyl‐CoA in normal rats, and slightly less in clofibrate‐treated animals. The wet weight and protein content of the liver increased by about 25%.
From livers of clofibrate‐treated rats, mitochondrial and lysosomal fractions were obtained in increased amounts by conventional tissue fractionation techniques. The supernatants from such livers had rather high activities of marker enzymes for lysosomes and peroxisomes.
No changes of the specific activities of the two first enzymes in the degradation pathway for CoA, i.e. acid phosphatase and nucleotide pyrophosphatase, were found in the liver homogenate from clofibrate‐treated rats. In the mitochondrial fraction from such livers, both (contaminating) activities were decreased. The degradation of CoA was increased in the supernatant, however, probably because of an increased leakage of acid phosphatase from lysosomes during the fractionation procedure.
The synthesis of CoA from pantothenic acid was estimated by two different methods in vitro: by quantitation of CoA formed and by estimation of the incorporation of [14C]pantothenic acid into CoA. By both methods, CoA synthesis was found to be increased 3–4‐fold in livers from clofibrate‐treated rats.
Dephospho‐CoA kinase was found to have a dual localization, with a minor pool in the mitochondrial fraction. This enzyme was only slightly increased in the clofibrate‐treated animals.
The activity of pantothenate kinase was more than doubled after clofibrate treatment. This is thought to be the most important factor for the increase of CoA. CoA exerted feed‐back inhibition at this step in liver supernatant from normal and clofibrate‐treated rats.
Deuterium Isotope Effects on Papain Acylation
Authors: POLGÁR László 
Published: March 2005

The experimental data presented in this paper comprise kinetic deuterium isotope effects on acylation of papain with various substrates when conducted in H2O and 2H2O. With alkyl esters of N‐acylamino acids there is no or very little isotope effect, whereas with N‐acylamino acid amides the ratio kH2O/k2H2O is less than 1, i.e. there is an inverse isotope effect. Similarly, alkylation of papain with methyl bromoacetate exhibits no kinetic isotope effect, whereas for the analogous alkylation with bromoacetamide an inverse isotope effect is observed.It is concluded that (a) general base catalysis does not occur in the acylation of papain and (b) kinetic deuterium isotope effects can be affected substantially by interaction between the substrate leaving group and the enzyme, which has not been considered in previous mechanistic investigations.
The Amino Acid Sequence of Mouse Pancreatic Ribonuclease
Authors: LENSTRA Johannes A. , BEINTEMA Jaap J. 
Published: March 2005

The complete amino acid sequence of mouse pancreatic ribonuclease has been determined by analysis of tryptic, chymotryptic, thermolytic and CNBr peptides and by automatic sequence analysis of the intact protein.The sequence of mouse RNase differs in 20–30% of the positions from other RNase sequences. Three unique or nearly unique substitutions were found, viz. Gly‐68 → Arg‐68, Arg‐85 → His‐85 and Ser‐123 → Thr‐123. All these three residues might be involved in interactions with substrate molecules.A most parsimonious tree of the myomorph rodent RNase shows that after the divergence of rat and mouse, the ribonuclease of rat accumulated substitutions at a rate 2.5–4.3 times as high as the rates in other branches of the tree and 23 times as high as the average rate in the Bovidae ribonuclease evolution. These extreme fluctuations in substitution rate are difficult to reconcile with the hypothesis of the evolutionary clock. The high evolution rate of rat ribonuclease is thought to be caused by positive selection, leading to new functional properties of the enzyme.