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7352990 | Isolation, physicochemical properties, and macromolecular composition of zona pellucida from porcine oocytes. | Oocytes released en masse from pig ovaries were isolated in large quantities by using sieving techniques. The isolated oocytes were gently homogenized, and the largely intact zona pellucida "ghosts" were purified by using sieving techniques. Sufficient amounts of zonae were recovered to permit, for the first time, adeq... |
6985841 | [Kinetic studies of the (1 linked to 4)-alpha-D-glucopyranosyltransferase reaction catalyzed by cyclodextrin glycosyltransferase, particularly the cyclization with amylose, amylopectin and total starch as substrate]. | The time course of the (1 leads to 4)-alpha-D-glucopyranosyltransfer reactions catalyzed by the cyclodextrin glycosyltransferase ((1 leads to 4)-alpha-D-glucan: [(1 leads to 4)-alpha-D-glucopyranosyl]transferase (cyclizing), EC 2.4.1.19, CGT) from Klebsiella pneumoniae was studied with several commercial amyloses, pota... |
6985840 | [Kinetic studies of the (1 linked to 4)-alpha-D-glucopyranosyltransferase reaction catalyzed by cyclodextrin glycosyltransferase, particularly the cyclization with (1 linked to 4)-alpha-D-glucopyranosyl chains (average polymerization of 16) as substrate]. | The transfer reactions, particularly the cyclization reaction, catalyzed by the cyclodextrin glycosyltransferase ((1 leads to 4)-alpha-D-glucan:[(1 leads to 4)-alpha-D-glucopyranosyl]-transferase (cyclizing), EC 2.4.1.19; CGT) from Klebsiella pneumoniae M 5 al were studied with (1 leads to 4)-alpha-D-glucopyranosyl cha... |
7350170 | Adhesion between liposomes mediated by the chlorophyll a/b light-harvesting complex isolated from chloroplast membranes. | A highly purified chlorophyll a/b light-harvesting complex (chl a/b LHC; chl a/b ratio 1.2) was obtained from Triton-solubilized chloroplast membranes of pea and barley according to the method of Burke et al. (1978, Arch. Biochem. Biophys. 187: 252--263). Gel electrophoresis of the cation-precipitated chl a/b LHC from ... |
7188610 | Dynamics of nuclear actin bundle induction by dimethyl sulfoxide and factors affecting its development. | We have reported in a previous paper that dimethyl sulfoxide (DMSO) induces the formation of huge bundles of actin filaments in the nuclei of Dictyostelium mucoroides. The present study was performed to provide electron microscope data on the induction of nuclear actin bundles, illustrating both their formation and the... |
16592754 | Supramolecular structure of stacked and unstacked regions of the photosynthetic membranes of Prochloron sp., a prokaryote. | Freeze-fracture replicas of the photosynthetic prokaryote Prochloron sp., collected at Coconut Island, Hawaii, show that the thylakoids are differentiated into stacked and unstacked regions much like the thylakoids of green algae and higher plants. On the exoplasmic (E) fracture face, the particle density is greater in... |
6812505 | Extraction of phospholipids from aldehyde-fixed membranes. | The effect of aldehyde fixation on membrane lipids and proteins has been studied. Purified fractions of toad retinal receptor outer segments were treated with a nonionic detergent after aldehyde fixation. Glutaraldehyde-fixed material retained proteins and phosphatidyl serine while other phospholipids were solubilized ... |
7333670 | Examination of Streptococcus mutans for immunoglobulin G Fc reactivity. | Representative strains of oral streptococci were tested for Fc immunoglobulin G (IgG) reactivity by two different techniques, agglutination of rabbit-IgG sensitized sheep erythrocytes and uptake of human and rabbit 125I-radiolabeled IgG. None of the S. mutans serotypes a through e reacted with the Fc region of either h... |
6276970 | [Pain and pain therapy - neurophysiologic view]. | Usually, pain is caused by the excitation of nociceptors or of nociceptive afferent fibers. The responsiveness of the nociceptors can be modulated by endogenously released algesic substances or local hormones. Lesioned and regenerating nerve fibers show enhanced excitability and spontaneous activity. Motor and sympathe... |
6799461 | Cycloheptaamylose-dansyl chloride complex as a fluorescent label of surface membranes in living ciliates. | Labelling of surface membrane of living ciliates: Paramecium aurelia and Tetrahymena pyriformis with fluorescent compound--cycloheptaamylose-dansyl chloride complex (CDC) has been achieved. Fluorescence micrographs of the dried samples showed specific localization of CDC on the cell membrane without any intracellular p... |
7326244 | Solution properties of synthetic chlorophyllide--and bacteriochlorophyllide--apomyoglobin complexes. | Well-defined 1:1 complexes have been formed between apomyoglobin (apoMb) and a number of chlorophyllide derivatives. The chlorophyllides substitute for heme in the pocket of myoglobin. These include magnesium chlorophyllide a, magnesium and zinc pyrochlorophyllide a, zinc pyrochlorophyllide b, zinc pyrochlorophyllide d... |
6895604 | Superoxide dismutase activity of macrocyclic polyamine complexes. | Copper(II) and nickel(II) complexes of macrocyclic polyamine derivatives possessing partial oligopeptide-like structures are found to suppress the xanthine-xanthine oxidase-mediated reduction of nitroblue tetrazolium and also to suppress formazan formation by potassium superoxide. The activity in the superoxide dismuta... |
7315937 | Atrophy of myelinated retinal nerve fibers after acute optic neuropathy. | A 45-year-old man with extensive myelinated retinal nerve fibers had an attack of anterior ischemic optic neuropathy. Serial fundus photographs documented the loss of myelin. Visual acuity in the affected eye decreased to 6/90 (20/300) and color perception was markedly reduced. The visual fields in the affected eye sho... |
16593130 | Generation of "bastard" molecular ions from van der Waals clusters: Ar(n)(C(2)Cl(4))(m) ions, suspected interlopers in collection of solar neutrinos. | Gaseous molecular ions containing argon and perchlorethylene, Ar(n)(C(2)Cl(4))(m) (+) in which n >/= 1-29 and m >/= 1-4, are produced by electron bombardment of van der Waals clusters formed by expanding an Ar/C(2)Cl(4) mixture through a supersonic nozzle. Previous attempts to observe such ions in a high-pressure mass ... |
16593128 | Transfer activity coefficients between water and methanol of complexes of some univalent and barium ions with dibenzocryptand 2.2.2, cryptand 2.2.2, and 18-crown-6. | Stability constants, K(f)LM(n+) (in which L = ligand and M(n+) = metal ion), of complexes of sodium, potassium, silver, thallium(I), and barium with dibenzocryptand 2.2.2 were determined at 25 degrees C in water and methanol. Also determined were transfer activity coefficients between methanol and water of two ligands,... |
6797111 | Complement changes during granulocyte adhesion. | The granulocyte adherence assay was investigated as a potential in vitro model of filtration leukapheresis to study the effects produced on the complement system by passing anticoagulated blood through columns packed with nylon fibers. Complement activation per se was found not to be a prerequisite for the simple attac... |
6118408 | Effects of cyclodextrins on chlorpromazine-induced haemolysis and central nervous system responses. | Cyclodextrins (CyDs) protected the human erythrocytes from haemolysis induced with chlorpromazine (CPZ) in isotonic solution, depending upon the magnitude of the stability constant of CPZ-CyD complexes (beta-greater than-gamma-greater than alpha-CyD). From the observations of CPZ uptake into erythrocytes and changes in... |
6118377 | Taxol binds to polymerized tubulin in vitro. | Taxol, a natural plant product that enhances the rate and extent of microtubule assembly in vitro and stabilizes microtubules in vitro and in cells, was labeled with tritium by catalytic exchange with (3)H(2)O. The binding of [(3)H]taxol to microtubule protein was studied by a sedimentation assay. Microtubules assemble... |
6273317 | Isolation of a protein-containing cell surface component from Streptococcus sanguis which affects its adherence to saliva-coated hydroxyapatite. | The isolation and partial characterization of a protein-containing cell surface component from Streptococcus sanguis which blocks the adherence of this microbe to saliva-coated hydroxyapatite are described. Several methods of extraction were attempted. Sonication of whole cells and cell walls proved to be the most succ... |
7298913 | Axonal guidance during development of the optic nerve: the role of pigmented epithelia and other extrinsic factors. | It is well established that a congenital lack of ocular melanin (albinism) can lead to developmental abnormalities of the central visual pathways. However, it is yet unknown how the pigmentation per se acts to influence formation of the optic projection. In order to study the possible interaction between eye pigment an... |
6795230 | Selective effects of glucocerebroside (Gaucher's storage material) on macrophage cultures. | Although the enzymatic lesion in Gaucher's disease is well established, little is known concerning the pathogenic mechanisms involved in the clinical manifestations of the disease. In order to obtain insight into this unexplored aspect of Gaucher's disease, we examined the effects of glucocerebroside (GL(1)) at the cel... |
7298607 | Structural heterogeneity and subcellular distribution of nicotinic synapse-associated proteins. | Peripheral membrane proteins (Mr = 43,000) are associated with Torpedo membranes highly enriched in nicotinic receptor. These 43,000-dalton proteins are not required for ion translocation or other known receptor functions, but they have been implicated in constraint of the nicotinic receptor within the plane of the mem... |
6795183 | Development-specific protein S of Myxococcus xanthus: purification and characterization. | Protein S, a development-specific protein of Myxococcus xanthus, was purified from the cells of a late stage of development and crystallized. Its circular dichroism spectra indicated that protein S had a high content of beta-structure in both the presence and absence of calcium ion, which is required for self-assembly ... |
7295711 | On the mechanism of action of polyether XXVIII at site I of the electron-transfer chain in rat liver mitochondria. | In rat liver mitochondria, the macrocyclic polyether, dibenzo-18-crown-6 (polyether XXVIII) inhibits the oxidation of NAD-dependent substrates, as stimulated by ADP, uncouplers and valinomycin plus K+. It does not inhibit the oxidation of succinate. It is concluded that polyether XXVIII inhibits electron transfer in th... |
7326341 | Some association properties of bovine SH-kappa-casein. | (1) It is shown that kappa-casein association is characterized by a critical micelle concentration which decreases as the ionic strength is increased. (2) The kappa-casein polymer molecular weight was calculated from the weight-average apparent molecular weight by taking into consideration the monomer concentration and... |
7312924 | Interaction between indometacin and beta-cyclodextrin. | CHINOIN-137 consists of indometacin and beta-cyclodextrin in a 1 : 2 molar ratio. solid phase analytical techniques, as thermal analysis, mass spectrometry and X-ray powder diffraction do not support the existence of a well-defined crystalline complex. However this product dissolved in water more readily and results in... |
6458492 | Formation of magnesium-phosphoenzyme and magnesium-calcium-phosphoenzyme in the phosphorylation of adenosine triphosphatase by orthophosphate in sarcoplasmic reticulum. Models of a reaction sequence. | The aim of the present study was to test simple reaction sequences which describe calcium-independent plus calcium-dependent phosphorylation of sarcoplasmic reticulum transport. ATPase by orthophosphate including the function of magnesium in phosphoenzyme formation. The reaction schemes considered were based on the rea... |
6272840 | Protein influences on porphyrin structure in cytochrome c: evidence from Raman difference spectroscopy. | To probe the details of protein heme interactions, we have developed a Raman difference spectroscopic technique, which allows reliable detection of very small, approximately equal to 0.01 cm-1, frequency differences. When this technique is applied to heme proteins, structural differences in the protein which perturb th... |
7197680 | Isolation and characterization of actin and actin-binding protein from human platelets. | Human blood platelets, which are highly motile cells essential for the maintenance of hemostasis, contain large quantities of actin and other contractile proteins. We have previously introduced a method (Lucas, R. C., T. C. Detwiler, and A. Stracher, J. Cell Biol., 1976, 70(2, Pt. 2):259 a) for the quantitative recover... |
7298713 | Thylakoid membrane biogenesis in Chlamydomonas reinhardtii 137+: cell cycle variations in the synthesis and assembly of polar glycerolipid. | The synthesis and assembly of thylakoid membrane polar glycerolipid (glycolipid, phospholipid, and ether lipid) have been monitored in synchronous cultures of the green alga Chlamydomonas reinhardtii 137+. A "pulse" protocol using radioactive acetate as the lipogenic precursor was devised to allow assessment of both pr... |
6270381 | Phosphorylation patterns of tumour antigens in cells lytically infected or transformed by simian virus 40. | The phosphorylation sites of simian virus 40 (SV40) large tumor (T) antigens have been analyzed by partial proteolysis peptide mapping and phosphoamino acid analysis of the resulting products. At least four sites were found to be phosphorylated. An amino-terminal part of the molecule contained both phosphoserine and ph... |
6270373 | Differences between poliovirus empty capsids formed in vivo and those formed in vitro: a role for the morphopoietic factor. | Empty capsid species formed from the self- and extract-mediated assembly of poliovirus type 1 14S particles in vitro and procapsids isolated from virus-infected cells were subjected to isoelectric focusing in charge-free agarose gels. The empty capsid formed in the self-assembly reaction had an isoelectric point (pI) o... |
7284553 | Time-dependent absorption anisotropy and rotational diffusion of proteins in membranes. | The decay of flash-induced absorption anisotropy, r(t), of a chromophore in a membrane protein is closely correlated with rotational diffusion of the protein in the membrane. We develop a theory of time-dependent absorption anisotropy which is applicable to both linear chromophores and planar chromophores which have tw... |
16593093 | Steric control of CO binding in a totally synthetic heme protein model. | A family of totally synthetic models for the carbon monoxide adducts of heme proteins has been synthesized and applied to the elucidation of the role of steric effects in the relative detoxification of carbon monoxide. The complexes are designed such that a sheltered void of controllable dimensions encompasses the CO b... |
7334457 | Enhanced bioavailability of digoxin by gamma-cyclodextrin complexation. | Inclusion complex of digoxin with gamma-cyclodextrin (gamma-CyD) in 1:4 molar ratio was prepared, and its dissolution and absorption behaviors were compared with those of digoxin alone. The dissolution rate of digoxin in water was found to be markedly increased by gamma-CyD complexation. Bioavailability of digoxin foll... |
7325975 | Characterization of the inhibition of fibrin assembly by fibrinogen fragment D. | Fragment D (Mr 100 000) prepared from a terminal plasmin digest of fibrinogen was isolated and used to study its effect on fibrin formation. Increasing amounts of fragment D added to a solution of fibrinogen and thrombin decrease the rigidity of the resultant gel (10% of control at 2 mol of fragment D/mol of fibrinogen... |
6272634 | Differential activity of potential antiviral nucleoside analogs on herpes simplex virus-induced and human cellular thymidine kinases. | Potential antiviral nucleoside analogs 1-beta-D-arabinofuranosylthymine, the 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-nucleosides of -5-methyluracil, -5-iodouracil, -5-methylcytosine, -5-iodocytosine, and -E-5-(2-bromovinyl)uracil, E-5-(2-bromovinyl)-2'-deoxyuridine, E-5-(2-bromovinyl)-1-beta-D-arabinofuranosylurac... |
6946487 | Exchange of 1,N6-etheno-ATP with actin-bound nucleotides as a tool for studying the steady-state exchange of subunits in F-actin solutions. | The fluorescent analog of ATP 1-N6-ethenoadenosine 5'-triphosphate (epsilon-ATP) exchanges readily with nucleotides bound to G-actin. The exchange can be observed by measuring the fluorescence intensity, which increases significantly when epsilon-ATP binds to actin. When excess epsilon-ATP is added to a solution of F-a... |
6946473 | Biosynthesis of porphyrins and heme from gamma, delta-dioxovalerate by intact hepatocytes. | The purpose of this study was to assess the ability of hepatocytes to synthesize porphyrins and heme from delta-aminolevulinic acid derived from gamma, delta-dioxovalerate and alanine. An alternate pathway for delta-aminolevulinic acid synthesis, in contrast to the condensation of succinate and glycine by delta-aminole... |
6170334 | Kinetic difference between hydrolyses of gamma-cyclodextrin by human salivary and pancreatic alpha-amylases. | gamma-Cyclodextrin was found to be hydrolyzed by human salivary and pancreatic alpha-amylases (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) at appreciable rates. The optimum pH for the enzyme reactions at 37 degrees C in the presence of 0.1 M NaCl was at around pH 5, which was remarkably different from the optimum ... |
6974918 | [Fluorescence anisotropy and myelin structure. IV. An analysis of the effect of temperature changes on the membrane structure]. | The temperature dependence of birefringence and fluorescent polarization of stained nerve fibers has been studied. Theoretical aspects of the determination of the orientation of chromophores from polarized emission experiments are aslo considered. The experiments with changing temperature permits a conclusion that the ... |
6270335 | A structure-activity relationship study of spirolactones. Contribution of the cyclopropane ring to antimineralocorticoid activity. | A series of spirolactones containing a cyclopropane ring in the molecule was examined for its effects on the mineralocorticoid receptor. The results were compared with those of a similar series of spirolactones in which the cyclopropane ring was replaced by a double bond. Insertion of a double bond or an alpha-cyclopro... |
7284234 | Application of monoclonal antibodies to purified CEA in clinical radioimmunoassay of human serum. | Double-antibody radioimmunoassay using a mouse monoclonal anti-CEA (MA/1) has been used to measure CEA in human serum. Low levels of MA/1-binding CEA have been found in serum from normal individuals and moderately raised levels are sometimes associated with certain non-malignant diseases. As with conventional anti-CEA,... |
7276161 | Altered spectrin dimer-dimer association and instability of erythrocyte membrane skeletons in hereditary pyropoikilocytosis. | Hereditary pyropoikilocytosis (HPP) is a hemolytic anemia characterized by microspherocytosis, poikilocytosis, and an unusual thermal sensitivity of erythrocytes. We have investigated the contribution of abnormal membrane skeletal assembly to these abnormal HPP erythrocyte properties. Skeletons prepared from fresh HPP ... |
7275929 | Semiaerobic induction of bacteriochlorophyll synthesis in the green bacterium Chloroflexus aurantiacus. | Comparison of Chloroflexus aurantiacus J-10-fl cells by freeze-fracture electron microscopy showed that cell shape and dimensions did not depend on oxygen tension or light intensity during growth. The major morphological difference between cells cultured anaerobically in the light and aerobically in the dark was the ab... |
7275928 | Isolation and development of chlorosomes in the green bacterium Chloroflexus aurantiacus. | Freeze-fracture electron microscopy was used to study further the changes in chlorosome structure during the development of the photosynthetic apparatus in Chloroflexus aurantiacus J-10-fl. During development, in response to decreased light intensity or lower oxygen tension, the number of chlorosomes per cell increased... |
7272603 | Drug-receptor recognition: molecular orientation and dielectric effects. | 1 The orientation of ethidium and its carboxyphenyl derivative was computed at various positions around one turn of the B-DNA helical receptor. 2 Dielectric effects of solvent were included using values for the bulk constant and a dielectric vector to simulate dielectric inhomogeneities. 3 From the electrostatic energy... |
7198910 | Pressure-jump studies on the length-regulation kinetics of the self-assembly of myosin from vertebrate skeletal muscle into thick filament. | The self-assembly of myosin monomer into thick filament occurs via a two-step mechanism. At first a pair of myosin monomers reacts to form a parallel dimer; the dimer in turn adds to the filament ends at a rate that is independent of filament length. The rate of the dissociation reaction on the other hand is length-dep... |
6946453 | Transformation of frog embryos with a rabbit beta-globin gene. | In order to study the fate and possible expression of foreign DNA during embryogenesis of the frog Xenopus laevis, we have injected a rabbit beta-globin gene into fertilized Xenopus eggs. Frog embryo DNA was extracted at various stages of development, fractionated by agarose gel electrophoresis, transferred to nitrocel... |
6946448 | Periodic synthesis of microtubular proteins in the cell cycle of Physarum. | Periodic polypeptide labeling over the naturally synchronous nuclear replication cycle of Physarum polycephalum was analyzed by fluorography of two-dimensional electropherograms. Two sets of polypeptides, denoted as P and Q, showed strong periodicity; they were maximally labeled just prior to mitosis. This periodicity ... |
6946445 | S phase-specific synthesis of dihydrofolate reductase in Chinese hamster ovary cells. | We investigated the cell cycle modulation of dihydrofolate reductase (DHFR; tetrahydrofolate dehydrogenase, 7,8-dihydroxyfolate:NADP+ oxidoreductase, EC 1.5.1.3) levels in methotrexate-resistant Chinese hamster ovary cells synchronized by mitotic selection. DNA content and DHFR concentration were analyzed throughout th... |
6272284 | Diphtheria toxin fragment forms large pores in phospholipid bilayer membranes. | The cytotoxic effect of diphtheria toxin requires the entry of its enzymatic A fragment (Mr approximately 21,000) into the cytosol of sensitive cells. We show that the B45 fragment (Mr approximately 24,000) forms, in lipid bilayers, pores that are large enough (diameter greater than or equal to 18 A) to allow the passa... |
6946434 | Structure of the fibrin protofibril. | We identified the two-stranded fibrin protofibril and studied its structure in electron micrographs of negatively stained specimens. Based on these images and on considerations of symmetry, we constructed a model of the protofibril in which the two strands of trinodular fibrin molecules are related by a two-fold screw ... |
6169728 | A nucleolar skeleton of protein filaments demonstrated in amplified nucleoli of Xenopus laevis. | The amplified, extrachromosomal nucleoli of Xenopus oocytes contain a meshwork of approximately 4-nm-thick filaments, which are densely coiled into higher-order fibrils of diameter 30-40 nm and are resistant to treatment with high- and low-salt concentrations, nucleases (DNase I, pancreatic RNase, micrococcal nuclease)... |
7285950 | The coincident distribution of calcium-rich membranes and kinetochore fibers at metaphase in living endosperm cells of Haemanthus. | We have coupled chlorotetracycline (CTC) fluorescence with polarized light microscopic observations of living mitotic endosperm cells of Haemanthus in order to compare the spatial distributions of Ca2+-rich endomembranes in the spindle with that of the kinetochore fibers during metaphase. In either control cells or in ... |
6791915 | Chemistry of carcinogenic metals. | The periodic distribution of known and suspected carcinogenic metal ions is described, and the chemical behavior of various types of metal ions is explained in terms of the general theory of hard and soft acids and bases. The chelate effect is elucidated, and the relatively high stability of metal chelates in very dilu... |
7272447 | Magic angle spinning carbon-13 NMR of tobacco mosaic virus. An application of the high-resolution solid-state NMR spectroscopy to very large biological systems. | Magic angle spinning 13C NMR was used to study tobacco mosaic virus (TMV) in solution. Well-resolved 13C NMR spectra were obtained, in which several carbon resonances of amino acids of the TMV coat protein subunits that are not observable by conventional high-resolution NMR spectroscopy can be designed. RNA resonance w... |
7272443 | Fluorescence photobleaching recovery in solutions of labeled actin. | We have demonstrated that the technique of fluorescence photobleaching recovery (FPR) can be used to examine the state of a single component in complex self-assembling macromolecular systems. Polymerization of actin, initiated by addition of salt or Mg+2 to a low-ionic-strength solution of G-actin, has been observed by... |
7263616 | Cytoplasmic helical structure associated with Acholeplasma laidlawii. | A distinct spiral protein structure was found in three species of Acholeplasma, but was not found in the Mycoplasma species studied. The spirals, which are 14 nm in width and of variable length from 50 to 300 nm, are formed by a helical arrangement of 7-nm subunits. A rosette-like structure 45 nm in diameter also compo... |
7259326 | Prostaglandin E1 infusions for vascular insufficiency in progressive systemic sclerosis. | Twelve patients with systemic sclerosis (SS) and severe Raynaud's phenomenon received infusions of prostaglandin E1 (PGE1) at a dose of 6-10 ng/kg/min, with either saline or 5% dextrose, for 72 hours in a single-blind cross-over study. The infusions were administered intravenously by centrally positioned catheters. Inf... |
6942054 | I-Kk and H-2Kk antigens are shed as supramolecular particles in association with membrane lipids. | The form of 125I-labeled membrane alloantigens (I-Ak and H-2Kk) and immunoglobulin M shed by murine splenic lymphocytes labeled by lactoperoxidase-catalyzed radioiodination was determined by gel chromatography and ultracentrifugation. I-Ak and H-2Kk antigens are shed as particles ranging in size from 3 X 10(5) to 2 X 1... |
6270686 | Monoclonal antibodies against beta nerve growth factor and their effects on receptor binding and biological activity. | Two hybrid cell lines, MC beta-1 and MC beta-2, secreting monoclonal antibodies against mouse submaxillary gland beta nerve growth factor (beta NGF), were produced by interspecies hybridization of spleen cells from rats immunized with beta NGF and mouse myeloma cells. The antibodies secreted by the two hybridomas are o... |
6270682 | Membrane attack complex of complement: distribution of subunits between the hydrocarbon phase of target membranes and water. | Membrane destruction by complement is effected by the membrane attack complex (MAC) which is the dimer of a fusion product of the complement proteins C5b, C6, C7, C8, and C9. Phospholipid bilayer vesicles were used as target membranes for the MAC and its intermediate complexes. The subunits of these membrane-bound comp... |
6170067 | Production of immunologically active surface antigens of hepatitis B virus by Escherichia coli. | Several plasmids have been constructed which direct the synthesis of hepatitis B virus surface antigens in Escherichia coli either as the native polypeptide or fused to other plasmid encoded polypeptides. When injected into rabbits, extracts from bacteria carrying some of these plasmids induced the synthesis of antibod... |
7027255 | Purified lexA protein is a repressor of the recA and lexA genes. | Escherichia coli shows a pleiotropic response (the SOS response) to treatments that damage DNA or inhibit DNA replication. Previous evidence has suggested that the product of the lexA gene is involved in regulating the SOS response, perhaps as a repressor, and that it is sensitive to the recA protease. We show here tha... |
6270661 | Site-specific interaction of DNA gyrase with DNA. | DNA gyrase, in the presence of the inhibitor oxolinic acid, can induce double-strand DNA breakage at specific sites. The sequences at several sites have been determined. In addition, the structure of complexes formed between DNA gyrase and restriction fragments containing an oxolinic acid-promoted cleavage site has bee... |
6457298 | Regulation of glycoprotein biosynthesis by formation of specific glycosyltransferase complexes. | Eukaryotic surfaces simultaneously express a complex array of protein-linked oligosaccharides and, during differentiation and on neoplastic transformation, these arrays change. The oligosaccharides linked to asparagine residues of proteins are a complex family of structures that are derived from a common precursor olig... |
6793359 | Purification, properties and assembly of the neck-appendage protein of the Bacillus subtilis phage phi 29. | The purification of the neck appendage protein of phi 29, p12*, which is involved in the adsorption of the phage to Bacillus subtilis, is described. The purified native protein is in a dimeric form and can be assembled, in vitro, onto purified 12- particles that lack the neck appendages, suggesting that the incorporati... |
7279667 | Replication of the extrachromosomal ribosomal RNA genes of Tetrahymena thermophilia. | Cultures of Tetrahymena thermophila were deprived of nutrients and later refed with enriched medium to obtain partial synchrony of DNA replication. Preferential replication of the extrachromosomal, macronuclear ribosomal RNA genes (rDNA) was found to occur at 40-80 min after refeeding. The rDNA accounted for one half o... |
7258156 | Use of alpha cyclodextrin to eliminate interference by nonesterified fatty acids in calcium measurements. | This study shows that nonesterified fatty acids cause underestimation of serum calcium by some colorimetric methods. The underestimation of calcium occurs infrequently, but can be as large as 20-30 mg/l. Preincubation of the sample with alpha cyclodextrin will eliminate this interference. The procedure is simple, inexp... |
7251856 | Characterization of the porphobilinogen deaminase deficiency in acute intermittent porphyria. Immunologic evidence for heterogeneity of the genetic defect. | The molecular pathology of the porphobilinogen (PBG)-deaminase deficiency in heterozygotes for acute intermittent porphyria (AIP) was investigated by means of biochemical and immunologic techniques. The stable enzyme-substrate intermediates (A, B, C, D, and E) of PBG-deaminase were separated by anion-exchange chromatog... |
7019221 | Structural interaction of cytoskeletal components. | Three-dimensional cytoskeletal organization of detergent-treated epithelial African green monkey kidney cells (BSC-1) and chick embryo fibroblasts was studied in whole-mount preparations visualized in a high voltage electron microscope. Stereo images are generated at both low and high magnification to reveal both overa... |
6894760 | Studies on the motility of the foraminifera. I. Ultrastructure of the reticulopodial network of Allogromia laticollaris (Arnold). | Allogromia laticollaris, a benthic marine foraminifer, extends numerous trunk filopodia that repeatedly branch, anastomose, and fuse again to form the reticulopodial network (RPN), within which an incessant streaming of cytoplasmic particles occurs. The motion of the particles is saltatory and bidirectional, even in th... |
18963047 | Ion-pair extraction and fluorimetric determination of potassium with 18-crown-6 and eosin. | A highly sensitive and selective fluorimetric determination of potassium is proposed, based on solvent extraction of the ion-pair formed between a large anion and the cationic complex of K(+) with a crown ether. Sensitivity is achieved by selection of a highly fluorescent counter-ion of the fluorescein group (eosin). A... |
17401970 | Assay of volatile oil-cyclodextrin complexes by pyrolyzis gas-chromatography. | A pyrolytic gaschromatographic process was developed for the routine assay of both cyclodextrin inclusion complexes, and for the differentiation of the mechanical mixture of the same oil with beta-cyclodextrin. The method is a direct assay of low material demand. |
6943577 | Possible functions of mesenchyme cell-derived fibronectin during formation of basal lamina. | Epithelial synthesis and secretion of basal lamina has been considered to be a general feature of various vertebrate epithelium-mesenchyme interacting systems (e.g., salivary gland, mammary gland, feather, hair, and tooth morphogenesis). It has been repeatedly assumed that embryonic ectoderm and ectodermal derivatives,... |
7251659 | Tubulin pools in differentiating neuroblastoma cells. | The distribution of tubulin in soluble, reversibly stabilized (assembled) and insoluble forms has been determined in neuroblastoma cells undergoing microtubule-dependent neurite elongation. Procedures were developed to obtain reproducible tubulin fractions and to assay total tubulin. Radioimmunoassays showed that both ... |
6165840 | Snyder-Theilen feline sarcoma virus P85 contains a single phosphotyrosine acceptor site recognized by its associated protein kinase. | Cells nonproductively transformed by a variant of the Snyder-Theilen strain of feline sarcoma virus (FeSV) expressed an 85,000-dalton polyprotein (P85) with associated tyrosine-specific protein kinase activity. We identified within this polyprotein a single tyrosine acceptor site for its enzyme activity. This acceptor ... |
7017164 | Escherichia coli traD(Ts) mutant temperature sensitive for assembly of RNA bacteriophage MS2. | We report here a study on the temperature-sensitive conjugational transfer-deficient mutant Escherichia coli JCFL39, carrying a traD(Ts) mutation, which is also temperature sensitive for group I RNA phages (MS2, f2, and R17). It is shown that, when the mutant was infected with MS2 at 42 degrees C, phage RNA replicated;... |
6165838 | Differences in mechanisms of transformation by independent feline sarcoma virus isolates. | The Gardner and Snyder-Theilen isolates of feline sarcoma virus (FeSV) have previously been shown to encode high-molecular-weight polyproteins with a transforming function and an associated tyrosine-specific protein kinase activity. Cells transformed by these viruses exhibited morphological alterations, elevated levels... |
6165711 | Periodic surface array in Caulobacter crescentus: fine structure and chemical analysis. | A periodic array structure on the cell surface of Caulobacter crescentus CB15 was revealed by electron microscopy of the cell envelope, using negative staining, thin-sectioning, and freeze-etching. This structural layer has been isolated from liquid cultures, in which large pieces of the two-dimensional array are shed ... |
7016518 | Assessment of environmental contaminant-induced lymphocyte dysfunction. | Although it has been established that environmental contaminants can alter immune function, the mechanisms of action have yet to be determined. This paper reviews the effects of hydrocarbon environmental contaminants on lymphocyte function and presents an approach which may serve to delineate the mechanisms of action. ... |
16593028 | Magnetic resonance spectroscopy of the primary state, P, of bacterial photosynthesis. | We have obtained the magnetic resonance spectrum of the radical pair state P(F) by using reaction yield detected magnetic resonance spectroscopy. The magnetic resonance spectrum is quite sensitive to the local environment of P(F). The data place limits on the lifetime of triplet P(F) and the distance of charge separati... |
7316955 | Purification of desmin from adult mammalian skeletal muscle. | A method has been developed for preparation of purified desmin from mature mammalian (porcine) skeletal muscle. A crude desmin-containing fraction was prepared by modification of procedures used for isolation of smooth-muscle intermediate-filament protein [Small & Sobieszek (1977) J. Cell Sci. 23, 243-268]. The desmin ... |
6454893 | Differential effects of glucocorticosteroids on the functions of helper and suppressor T lymphocytes. | The effects of dexamethasone (Dex) on the functions of antigen-primed helper and suppressor T cells were studied in humoral immune responses in vitro. In doses equivalent to elevated physiologic concentrations, the suppressor T cell activity was abolished. In contrast, the helper T cell function was resistant to even p... |
6454891 | Ovine prolactin: equilibrium characteristics of the recombinant molecule formed by noncovalent interaction of two fibrinolysin fragments by fluorescence polarization. | The equilibrium characteristics of the recombined molecule formed by noncovalent interaction of two fibrinolysin fragments of ovine prolactin (oPRL) have been studied with fluorescence polarization. Fluorescein isothiocyanate (isomer I) was used to label oPRL-(1-53), creating a fluorescent peptide indistinguishable fro... |
7251153 | Human sex hormones stimulate the growth and maturation of Coccidioides immitis. | Because men and pregnant women show increased susceptibility to extrapulmonary dissemination of coccidioidomycosis, studies were conducted to determine the direct effect of human sex hormones and related compounds on the growth and maturation of Coccidioides immitis in vitro. 17 beta-Estradiol, progesterone, and testos... |
6264128 | Unusual lectin-binding properties of a herpes simplex virus type 1-specific glycoprotein. | Lysates from herpes simplex virus type 1-infected cells were subjected to affinity chromatography on soybean and Helix pomatia lectins. One of the virus-specified glycoproteins, probably the herpes simplex virus type 1-specific gC glycoprotein, bound to the lectins and was eluted with N-acetylgalactosamine. The affinit... |
7236853 | The role of subunit entropy in cooperative assembly. Nucleation of microtubules and other two-dimensional polymers. | The self-assembly and nucleation of two-dimensional polymers is described by a theory based on a model of rigid subunits and bonds and simple principles of thermodynamics. The key point in the theory is to separate as an explicit parameter the free energy, primarily attributed to the entropy of the free subunit, that i... |
6786347 | The effect on photosynthetic electron transport of temperature-dependent changes in the fluidity of the thylakoid membrane in a thermophilic blue-green alga. | Various electron transport reactions in cell or isolated thylakoid membranes of the thermophilic blue-green alga, Synechococcus sp. were measured at different temperatures between 72 and 3 degrees C. They are classified into two groups with respect to their temperature dependency. The first group involves cytochrome 55... |
7012129 | Multiple forms of alkaline phosphatase from Escherichia coli cells with repressed and derepressed biosynthesis of the enzyme. | Isolation of multiple forms of alkaline phosphatase from Escherichia coli cells with repressed and derepressed biosynthesis of the enzyme is reported. Three enzyme forms were isolated from cells with derepressed synthesis, and one form was isolated from cells with repressed enzyme synthesis. The multiple enzyme forms d... |
16593015 | Monomeric chlorophyll a enol: Evidence for its possible role as the primary electron donor in photosystem I of plant photosynthesis. | The chlorophyll a (Chl a) special-pair model of the primary donor of photosystem I (P700) does not account in a completely adequate fashion for the magnetic resonance properties observed for P700(+). Moreover, P700 is at least 420 mV easier to oxidize than is Chl a in vitro. Neither Chl a dimer formation nor selective ... |
16593010 | pi cation radicals of ferrous and free base isobacteriochlorins: Models for siroheme and sirohydrochlorin. | Theoretical and experimental optical, redox, and paramagnetic results are presented for models of siroheme, the iron isobacteriochlorin prosthetic group of nitrite and sulfite reductases, and of sirohydrochlorin, the metal-free siroheme that is an intermediate in the biosynthetic pathway to vitamin B(12). The facile ox... |
6167695 | Characteristics of growth-associated polypeptides in regenerating toad retinal ganglion cell axons. | We report here certain properties of three polypeptides that are rapidly transported in greatly increased amounts during the regeneration of toad optic nerves. All three of these growth-associated polypeptides (GAPs) are associated with a membrane(s) with a buoyant density similar to the plasma membrane. Since none of ... |
6267225 | Characterization of benzodiazepine and gamma-aminobutyric recognition sites and their endogenous modulators. | The solubilization and partial purification from rat brain cortex homogenates of [3H]gamma-aminobutyric acid (GABA) and [3H]diazepam recognition sites and of their endogenous modulators (GABA-modulin and an endogenous compound which specifically bound [3H]diazepam) are reported. A high percentage of GABA binding sites ... |
7255530 | Influencing of resorption and side-effects of salicylic acid by complexing with beta-cyclodextrin. | After oral administration of 14C-labelled salicylic acid and its beta-cyclodextrin complex to rats, the blood radioactivity-level increases in the first 2 h than decreases. The blood level obtained with the inclusion complex is somewhat but not significantly lower than with free acid. Since the resorption of cyclodextr... |
6941294 | Specific binding of solubilized adenylate cyclase to the erythrocyte cytoskeleton. | Concepts and criteria that have been developed for the study of the molecular organization of membrane-associated proteins are employed here to investigate the interaction of adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] with other membrane components. Detergent-solubilized adenylate cyclase can b... |
6264473 | Matrix protein in planar membranes: clusters of channels in a native environment and their functional reassembly. | Planar bilayers formed from Escherichia coli outer membrane vesicles exhibit conductance properties similar to those previously observed in bilayers reconstituted from aggregates of matrix protein, the major outer membrane protein. Discrete conductance steps are observed, reflecting voltage-dependent transmembrane chan... |
6454005 | Cellular location of Mu DNA replicas. | To ascertain the form and cellular location of the copies of bacteriophage Mu DNA synthesized during lytic development, DNA from an Escherichia coli lysogen was isolated at intervals after induction of the Mu prophage. Host chromosomes were isolated as intact, folded nucleoids, which could be digested with ribonuclease... |
7238507 | A bacterial glucoamylase degrading cyclodextrins. Partial purification and properties of the enzyme from a Flavobacterium species. | A Flavobacterium species has been isolated which produces a cyclodextrin-degrading glucoamylase. The inducible, cell-bound enzyme was purified about 10-fold to 75% purity in 57% yield. The action of the enzyme was studied with the main cyclodextrins (cyclohexaamylose, cycloheptaamylose and cyclooctaamylose) and with th... |
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