id stringlengths 4 8 | title stringlengths 1 642 | abstract stringlengths 50 17.9k |
|---|---|---|
7248451 | Studies on the mechanism of assembly of tobacco mosaic virus. | Sedimentation and proton binding studies on the endothermic self-association of tobacco mosaic virus (TMV) protein indicate that the so-called "20S" sedimenting protein is an interaction system involving at least the 34-subunit two-turn yield cylindrical disk aggregate and the 49-subunit three-turn helical rod. The pH ... |
7248449 | RNA-protein interactions in the assembly of tobacco mosaic virus. | Assembly of tobacco mosaic virus is initiated by the binding of a specific loop of the RNA into the central hole of the disk aggregate of protein subunits. Since the nucleation loop is located about five-sixths along the RNA molecule, subsequent elongation must be bidirectional. We have now measured the rates of elonga... |
6264986 | The structure of a DNA unwinding protein and its complexes with oligodeoxynucleotides by x-ray diffraction. | The structure of the gene 5 DNA unwinding protein from bacteriophage fd has been solved to 2.3 A resolution by x-ray diffraction techniques. The molecule contains an extensive cleft region that we have identified as the DNA binding site on the basis of the residues that comprise its surface. The interior of the groove ... |
6894706 | Movement and self-control in protein assemblies. Quasi-equivalence revisited. | Purposeful switching among different conformational states exerts self-control in the construction and action of protein assemblies. Quasi-equivalence, conceived to explain icosahedral virus structure, arises by differentiation of identical protein subunits into different conformations that conserve essential bonding s... |
6781491 | Ready separation of proteins from nucleoprotein complexes by reversible modification of lysine residues. | Modification of proteins with citraconic anhydride altered the electrostatic relationship between cationic epsilon-NH3+ groups of lysine residues of proteins and anionic phosphate groups of nucleic acids, thereby destabilizing the nucleoprotein complex. This procedure facilitated the separation of proteins from nucleic... |
7192627 | Mitosis in Oedogonium: spindle microfilaments and the origin of the kinetochore fiber. | New ultrastructural observations of mitosis in the closed spindle of Oedogonium cardiacum have been made using cells fixed with glutaraldehyde and tannic acid. Fine filaments 5 to 8 nm in diameter are attached to kinetochores from prophase through anaphase. Some are free in the early division nucleus while others emana... |
7444977 | Toxicity of butylbenzyl phthalate (BBP) and other phthalate esters to nervous tissue in culture. | Butylbenzyl phthalate (BBP) and n-butyl lauryl phthalate (BLP) markedly inhibited the outgrowth of nerve fibers and glial cells from cerebellar explants of newborn rat in primary culture at concentrations of 7.0 and 12.5 x 10(-4) M, respectively. The toxicity of butyl phthalyl butyl glycolate (BPBG) was not significant... |
6934523 | Spreading of fibroblasts in medium containing cytochalasin B: formation of lamellar cytoplasm as a combination of several functional different processes. | Normal cultured mouse fibroblasts spreading on solid substrate extend and attach numerous pseudopods; lamellar cytoplasm is eventually formed from the attached pseudopods. Fibroblasts spreading in the presence of cytochasin B (CB) from de novo a system of arbor-like branched processes rather than lamellar cytoplasm. Th... |
6160475 | Monoclonal antibodies to Escherichia coli 50S ribosomes. | Hybridoma cell lines that produce monoclonal antibodies directed against 50S Ribosomal proteins have been isolated. Spleen cells (from BALB/c mice immunized with 50S ribosomal subunits extracted from Escherichia coli) were fused to mouse myeloma cell line SP2/O-Ag 14. The initial screening for antibody producing hybrid... |
6776150 | Immunochemical and ultrastructural study of multiple myeloma with a heavy chain protein in the serum. | A patient with multiple myeloma had antigenically related monoclonal Fc-gamma fragments and complete IgG-kappa molecules in the serum. The urine contained only Fc-gamma fragments in the absence of Bence-Jones protein. The two distinct M-components in the serum showed electrophoretic identity but could be separated by c... |
7420024 | Effects of soluble immune complexes on Fc receptor- and C3b receptor-mediated phagocytosis by macrophages. | The effects of ingestion of soluble immune complexes upon macrophage phagocytic function was studied. Ingestion of immune complexes severely impaired the macrophage's ability to ingest IgG-coated particles but did not alter its ability to interact with particles by means other than its Fc receptors. Treatment of macrop... |
7419596 | Electron microscope evidence for the presence of globular structures in different sperm chromatins. | Dispersion of nuclear fibers of the spermatozoa of dogfish, man, and bull is made possible after treatment with a reducing and alkylating reagent coupled with an anionic detergent; the same detergent used at a low ionic strength dissociates the nuclear content of the rainbow trout sperm. Electron microscopy of such dis... |
6998971 | Methyl-alpha-maltoside and 5-thiomaltose: analogs transported by the Escherichia coli maltose transport system. | Neither methyl-alpha-maltoside nor 5-thiomaltose is utilized by Escherichia coli as a sole carbon source. Both are, however, effective competitive inhibitors of maltose transport into the bacterium (Km for maltose, 0.8 microM, Ki for methyl-alpha-maltoside, 5.5 microM; Ki for 5-thiomaltose, 0.2 microM). Both analogs ar... |
7417433 | Dissociation of supramolecular complexes in chloroplast membranes. A manifestation of heat damage to the photosynthetic apparatus. | High temperature-induced alterations to membrane structure were investigated for chloroplast thylakoid membranes isolated from leaves of Nerium oleander grown at a 20/15 degrees C or 45/32 degrees C day/night temperature regime and pretreated at temperatures from 40 to 55 degrees C. Quantitative analysis of micrographs... |
18962783 | Properties of cis- and trans-bis(crown ether)s for complexation and extraction of alkali metal picrates. | The properties of cis- and trans-bis(crown ether)s containing benzo-15-crown-5 or benzo-18-crown-6 units as complexants and extractants for alkali metal picrates have been studied. The optical spectra suggest that the cis-bis(crown ether)s can form intramolecular 2:1 crown ether unit/cation complexes with particular me... |
16592883 | Photophysical properties of zinc and magnesium tris(pyrochlorophyllide a) 1,1,1-tris(hydroxymethyl)ethane triesters. | The zinc and magnesium tris(pyrochlorophyllide a) 1,1,1-tris(hydroxymethyl)ethane triesters have properties that are very similar to those exhibited by pairs of pyrochlorophyll a or chlorophyll a linked by ethylene glycol through their propionic acid side chains. In the open configuration, the fluorescence lifetimes an... |
6254072 | Cloning of an origin of DNA replication of Xenopus laevis. | DNA fragments of Xenopus laevis, the African frog, were cloned in the EcoRI site of the Escherichia coli plasmid pACYC189 and tested for ability to initiate and complete replication of the recombinant plasmid when injected into unfertilized eggs of X. laevis. After measurement of the [3H]-thymidine incorporation per eg... |
6933560 | A colchicine-sensitive uptake system in Morris hepatomas. | The interference of microtubular disruptors with the uptake of amino acids and other low molecular weight substrates has been studied in Morris hepatomas, host liver, and regenerating liver. Colchicine inhibits amino acid transport (alpha-aminoisobutyric acid, L-methionine, and L-leucine) in hepatomas by 59-98% whereas... |
6253401 | Effect of immunosuppression on recurrent herpes simplex in mice. | Mice latently infected with herpes simplex virus were treated with immunosuppressive drugs either alone or combined with stimuli to the skin. Treatment with cyclophosphamide reduced spleen weights and severely depressed lymphocyte levels, but had no effect on healing after cellophane tape stripping (CTS) and did not af... |
7420542 | Growth dynamics of a latent primate papovavirus. | The stumptailed macaque papovavirus strain HD was discovered in a persistently infected cell line of primate origin designated Vero 76 (K. Bosslet and G. Sauer, J. Virol. 25:596--607, 1978; W. Waldeck and G. Sauer, Nature [London] 269:171--173, 1977). In clonal derivatives of Vero 76 cells a minor and variable proporti... |
6999171 | Role of the host cell in bacteriophage T4 development. II. Characterization of host mutants that have pleiotropic effects on T4 growth. | Mutant host-defective Escherichi coli that fail to propagate bacteriophage T4 and have a pleiotropic effect on T4 development have been isolated and characterized. In phage-infected mutant cells, specific early phage proteins are absent or reduced in amount, phage DNA synthesis is depressed by about 50%, specific struc... |
6252334 | Correlation of RNA binding affinity of avian oncornavirus p19 proteins with the extent of processing of virus genome RNA in cells. | We purified the p19 proteins from the Prague C strain of Rous sarcoma virus, avian myeloblastosis virus, B77 sarcoma virus, myeloblastosis-associated virus-2(0), and PR-E 95-C virus and measured their binding affinities for 60S viral RNA by the nitrocellulose filter binding technique. The apparent association constants... |
7419609 | Adhesion sites of murine fibroblasts on cold insoluble globulin-adsorbed substrata. | The attachment and detachment behavior of three mouse fibroblast cell lines adhering to plastic tissue culture substrata coated with the serum protein cold-insoluble globulin (CIg) resembles that seen on the usual serum-coated substrata. The transformed cell line SVT2 spreads more extensively on the CIg-coated than on ... |
6157696 | Addition of poly(A) to nuclear RNA occurs soon after RNA synthesis. | A kinetic analysis of the appearance of [3H]uridine label in RNA sequences that neighbor poly(A), as well as the incorporation of [3H]adenosine label into both the RNA chain and the poly(A) of poly(A)-containing molecules, shows that poly(A) is added within a minute or so after RNA chain synthesis in Chinese hamster ov... |
16592876 | Anchorage-independent muscle cell differentiation. | Cells from embryonic chicken muscle were cultivated in serum-free medium. After two days, the suspended cells (almost all of which were nondividing myoblasts) were subcultured in serum-containing medium, either in gelatincoated tissue culture dishes (to promote reattachment) or in bacteriological dishes (to prevent rea... |
16592871 | Relationship between transfer activity coefficients, gamma, of cryptate 2.2.2 complexes and their stability constant in various solvents. | Between dipolar aprotic solvents S(1) and S(2), the transfer activity coefficients, (S(1) )gamma(S(2) ), of complexed sodium, potassium, thallium(I), and silver ions with cryptand 2.2.2 have been found to be equal to that of the cryptand. With reference to methanol (S(1)), this equality does not hold, the cryptates bei... |
7011984 | Immunobiology of germfree mice infected with Nocardia asteroides. | Nocardia asteroides GUH-2 was administered either intranasally or by intravenous inoculation into (i) conventionally grown, (ii) germfree, and (iii) lipopolysaccharide-treated germfree NIH:S mice. The number of bacteria within the lungs, brain, kidneys, adrenals, liver, spleen, and blood was quantitated at 3, 24, 72, a... |
7203007 | Genetic analysis of the relationships between the cell surface and the nuclei in Paramecium tetraurella. | In Paramecium tetraurelia, a number of mutations have been shown to affect simultaneously cortical organization (attachment of trichocysts to the cortex) and nuclear divisions (Ruiz et al. 1976). In order to analyze the genetic and physiological basis of this correlation, and we have isolated new mutations affecting th... |
7459690 | Cleavage of protected amino acids and peptides from benzyl ester resins by transesterification with potassium cyanide in benzyl alcohol. | The nature of the protected amino acid or peptide attached to the Merrifield resin influences the rate of KCN-catalyzed transesterification in benzyl alcohol. Although crown ether complexes of KCN do not expedite the reaction, sterically hindered amino acids are readily transesterified in the presence of saturating con... |
6160381 | Precise determination of protein antigenic structures has unravelled the molecular immune recognition of proteins and provided a prototype for synthetic mimicking of other protein binding sites. | Intensive research in the author's laboratory had culminated in the determination and synthesis of all the antigenic sites of myoglobin in 1975 and of lysozyme in 1978. Very recently most of the antigenic sites of serum albumin were also localized and synthesized. These investigations provided the first unique insight ... |
6254041 | Genetic recombination of bacterial plasmid DNA: electron microscopic analysis of in vitro intramolecular recombination. | a tetramer of pMB9 DNA containing a single EcoRI site per tetramer was used to investigate intramolecular recombination in Escherichia coli. When transformed into wild-type E. coli strains, the tetramer was converted into dimers and a small proportion of trimers and monomers. The conversion was blocked in recA strains ... |
6159634 | Fidelity of structure representation in electron micrographs of negatively stained protein molecules. | We have investigated the fidelity of structure representation in electron micrographs of negatively stained proteins by conducting a systematic evaluation of such micrographs in terms of a known molecular structure, solved by x-ray crystallography. Microcrystals of immunoglobulin G Dob were used as specimens in this co... |
6933513 | Hydrophobic basis of packing in globular proteins. | The self-assembly of globular proteins is often portrayed as a nucleation process in which the hydrogen bonding in segments of secondary structure is the precondition for further folding. We show here that this concept is unlikely because both the buried interior regions and the peptide chain turns of the folded protei... |
6933494 | Observation of an exothermic process associated with the in vitro polymerization of brain tubulin. | The polymerization of tubulin has been studied with a high-sensitivity differential scanning microcalorimeter, with results which indicate that microtubule assembly can proceed via one or possibly two exothermic reactions. The amount of heat evolution has been found to be far in excess of GTP hydrolysis. The heat liber... |
7412095 | [Lipid peroxides and atherosclerosis. Hypothesis: the role of cholesterol and free-radical lipid peroxidation in altering cell membrane properties in hypercholesterolemia and atherosclerosis]. | When experimental animals are kept on an atherogenic diet the NADP.H-dependent phospholipid deoxygenase in the membranes of the hepatic endoplasmic reticulum is activated and the degree of membrane oxidation is increased. "Peroxide" modification of microsomal membranes is attended by changes in their conformation and a... |
7190570 | Distribution of fluorescently labeled alpha-actinin in living and fixed fibroblasts. | The distribution of flourescently labeled alpha-actinin after microinjection into fibroblasts has been determined in both living and fixed cells. We have found that the distribution of the injected tetramethylrhodamine isthiocyanate-labeled protein (TMRITC-alpha-actinin) in living cells, which is in ruffling membranes,... |
7400129 | Adenosine 5'-(2-bromoethyl)-phosphate. A new affinity label for adenine nucleotide sites in proteins. | A new adenosine analogue adenosine 5'-(2-bromoethyl)-phosphate has been synthesized. The reactive moiety, a bromoalkyl group, has the ability to react with the nucleophilic side chains of several amino acids. This compound reacts with NAD-dependent isocitrate dehydrogenase from pig heart, causing inactivation. Addition... |
6163844 | An axoplasmic component of the Schmidt-Lanterman deformation. | In three instances, peripheral nerves containing numerous Schmidt-Lanterman discontinuities of myelin revealed transverse, wedge-shaped, or arrowhead-shaped axoplasmic excrescences visible with axon stains. These were arranged with a frequency and length like that of the myelin clefts, but the axonal materials were loc... |
6255369 | Electrophysiological characteristics of crayfish inhibitory. | Parameters of IPSPs and characteristics of inhibitory neuromuscular transmission in the dactylopodite-opener muscle of the crayfish pincer at various rhythms of activity were studied by intracellular recording. The presynaptic conduction nature of high-frequency (pessimal) blockade of the inhibitory system was demonstr... |
7433096 | Mapping sequences in loops of nuclear DNA by their progressive detachment from the nuclear cage. | Nuclear DNA is organised into loops, probably by attachment to a supramolecular structure. We describe a method which enables us to map the position of sequences within a loop relative to the point of attachment. Nuclear DNA is isolated unbroken by lysing HeLa cells in 2M NaCl to release structures which retain many of... |
6106646 | Association of actin with sperm centrioles: isolation of centriolar complexes and immunofluorescent localization of actin. | The centrioles of cnidarian sperm associate with striated specializations (pericentriolar processes) during spermiogenesis. Three functions have been proposed for the role of these structures: (a) an anchoring mechanism for the sperm flagellum, (b) a signal-transmitting mechanism for communication between sperm head an... |
6893454 | Implications of treadmilling for the stability and polarity of actin and tubulin polymers in vivo. | In this report, we examine how the cell can selectively stabilize anchored filaments and suppress spontaneous filament assembly. Because microtubules and actin filaments have an organized distribution in cells, the cell must have a mechanism for suppressing spontaneous and random polymerization. Though the mechanism fo... |
6893453 | Biochemical analysis of actin in crane-fly gonial cells: evidence for actin in spermatocytes and spermatids--but not sperm. | A biochemical assay employing DNase-I affinity chromatography, two-dimensional peptide analysis and SDS polyacrylamide gel electrophoresis was used to isolate, identify, and assess the amount of actin from gonial cells of the crane fly, Nephrotoma suturalis. Based on the analysis of cell homogenates under conditions in... |
6157424 | Light-scattering studies of cation-stimulated filament assembly of newborn rat epidermal keratin. | Effects of CaCl2 on in vitro polymerization of keratin extracted from cornified cells of newborn rat were investigated by means of light-scattering and supramolecular structures. Elongation and parallel assembly of filaments occurred with addition of CaCl2 to dialyzed keratin solutions and was detected by an increase i... |
6250064 | Feline sarcoma virus polyprotein P115 binds a host phosphoprotein in transformed cells. | Several independent isoltes of feline sarcoma virus (FeSV) have been described. Such viruses are apparently derived by genetic recombination between feline leukaemia virus (FeLV) genomic RNA and host cellular genetic sequences with transforming potential. Two FeSV isolates, one originally described by Gardner and the s... |
6993990 | Factors influencing osmotic fragility of red blood cells in Duchenne muscular dystrophy. | Factors affecting osmotic fragility were studied in red blood cells of patients with Duchenne muscular dystrophy. The mean osmotic fragility (MOF), operationally defined as the NaCl concentration for 50% hemolysis, was found to be higher by 3.63 +/- 0.51 mM in Duchenne cells than in normal cells having an MOF of 60.1 +... |
6821371 | Association of glyceraldehyde 3-phosphate dehydrogenase with the membrane of the intact human erythrocyte. | Intact human erythrocytes were exposed to low concentrations of glutaraldehyde. After washing and subsequent lysis of the cells, glyceraldehyde 3-phosphate dehydrogenase activity is found to be associated with a membrane fraction and cannot be eluted by salt treatment. Lactate dehydrogenase activity is associated with ... |
6266530 | Study of anisotropy in nuclear magnetic resonance relaxation times of water protons in skeletal muscle. | The anisotropy of the spin-lattice relaxation time (T1) and the spin-spin relaxation times (T2) of water protons in skeletal muscle tissue have been studied by the spin-echo technique. Both T1 and T2 have been measured for the water protons of the tibialis anterior muscle of mature male rats for theta = 0, 55, and 90 d... |
7443510 | DNA-like duplexes with repetitions. I. Properties of concatemer duplexes formed by d(T-G-C-A-C-A-T-G). | A new class of synthetic DNA duplexes containing repeating oligonucleotide sequences, double-helical concatemers, is characterized. The UV-absorption and circular dichroism of a concatemer formed in self-association of d(T-G-C-A-C-A-T-G) have been studied. The thermodynamical parameters of complex formation are the fol... |
7440813 | Intraepithelial elastic fibers and intracytoplasmic glycogen: diagnostic aids in differentiating keratoacanthoma from squamous cell carcinoma. | A significant statistical difference was found between the incidence of intraepithelial elastic fibers in keratoacanthoma and squamous cell carcinoma arising in actinic keratosis (P < 0.001). There was no significant difference when keratoacanthoma was compared to adenoid squamous cell carcinoma (P = 0.13) and de novo ... |
6448744 | Long-term hazards of polychlorinated dibenzodioxins and polychlorinated dibenzofurans. | During January 10-11, 1978 in Lyon, France, a joint National Institute of Environmental Health Sciences/International Agency for Research on Cancer ad hoc Working Group considered and discussed the feasibility of coordinating epidemiological studies on the long-term hazards associated with the chlorinated dibenzo-p-dio... |
6251456 | Multienzyme complex for metabolic channeling in mammalian DNA replication. | In the DNA-synthesizing phase (S phase) of CHEF/18 Chinese hamster embryo fibroblast cells, six enzymes associated with DNA metabolism, including DNA polymerase (deoxynucleoside triphosphate:DNA deoxynucleotidyl-transferase, EC 2.7.7.7), were largely localized in the nuclear region (karyoplasts). By contrast, in quiesc... |
7391142 | Functional implications of cold-stable microtubules in kinetochore fibers of insect spermatocytes during anaphase. | In normal anaphase of crane fly spermatocytes, the autosomes traverse most of the distance to the poles at a constant, temperature-dependent velocity. Concurrently, the birefringent kinetochore fibers shorten while retaining a constant birefringent retardation (BR) and width over most of the fiber length as the autosom... |
6771297 | Cytoskeletal network underlying the human erythrocyte membrane. Thin-section electron microscopy. | A filamentous network underlying the human erythrocyte membranes can be clearly visualized in situ by electron microscopy of thin sections of specimens fixed with tannic acid-glutaraldehyde. The network is composed of two layers: the first, a layer of vertical components with granular appearance, which are seen to be d... |
6248247 | In vitro catenation and decatenation of DNA and a novel eucaryotic ATP-dependent topoisomerase. | Extracts from X. laevis germinal vesicles interlock duplex DNA circles to form catenanes. The catenation activity requires Mg++ and ATP. Negatively supercoiled or relaxed DNA can be used as substrates for the catenation reaction. Homology between donor and acceptor DNA is not required, since catenanes are formed betwee... |
6991628 | Monovalent fragments (Fab) of monoclonal antibodies to a sporozoite surface antigen (Pb44) protect mice against malarial infection. | Monoclonal antibodies (IG1, k) directed against a surface component of Plasmodium berghei sporozoites (Pb-44) confer complete protection to mice against a lethal inoculum of parasites. The degree of protection is a function of the number of parasites used in the challenge and of the antibody concentration in serum. Pas... |
16345578 | Accumulation of Soybean Lectin-Binding Polysaccharide During Growth of Rhizobium japonicum as Determined by Hemagglutination Inhibition Assay. | A hemagglutination inhibition assay was used to estimate the presence of soybean lectin-binding polysaccharide in whole culture, culture supernatant, and isolated exopolysaccharide of Rhizobium japonicum USDA 138. The occurrence of 0.1 to 0.2 mug of lectin-binding polysaccharide could be detected within 2 h with a 0.5-... |
6161445 | Alcoholic Bouin fixation of insect nervous systems for bodian silver staining. III. A shortened, single impregnation method. | Satisfactory Bodian silver staining of paraffin wax sections of both locust (Schistocerca gregaria) and cockroach (Periplaneta americana) central nerve tissue can be obtained with only one impregnation, instead of the usual two, by the following modified procedure. Freshly dissected ganglia are fixed in an improved syn... |
7001709 | [Potentiometric titration in biological studies]. | The employment of the potentiometric titration method for determination of the nature and concentration of ionized groups in synthetic polyelectrolytes, biopolymers and in membrane fragments of the cell has been considered. The interpretation of the results of potentiometric investigations in the biological system is c... |
7412376 | [2 cases of ovarian struma]. | The authors present two patients, aged 48 and 54 respectively, treated surgically for the alleged tumor of the ovary which histologically proved to be the struma of the ovary. In one patient the tumor behave as a benign one, while in the other there was also ascites--simpto mof malignant tumour. After surgery all disor... |
7400994 | Isolation and partial characterization of surface membranes from Leishmania donovani promastigotes. | Cell surface pellicular membranes (PM) were isolated from promastigote forms of Leishmania donovani by differential and discontinuous sucrose gradient centrifugation procedures. The PM had a density equivalent of approximately 1.19 g/cm3. As ascertained by electron microscopy, longitudinal parallel arrays of subpellicu... |
6901662 | The effects of octylglucoside on the Semliki forest virus membrane. Evidence for a spike-protein--nucleocapsid interaction. | Evidence is presented for a non-covalent interaction between the spike glycoprotein and the nucleocapsid of Semliki Forest virus. When isolated viruses were treated with the non-ionic detergent beta-D-octylglucoside at neutral pH and low ionic strength the lipid bilayer membrane could be removed leaving most of the spi... |
6930684 | Functional acetylcholine receptor from Torpedo marmorata in planar membranes. | Planar bilayer membranes containing functional acetylcholine receptor were formed from vesicles of Torpedo marmorata electric organ without extracting the acetylcholine receptor from its native environment. Native vesicles were transformed into monolayers which subsequently were apposed into planar bilayers. In the abs... |
6930653 | Structure of a mycobacterial polysaccharide-fatty acyl-CoA complex: nuclear magnetic resonance studies. | MMP, a linear alpha 1 leads to 4 linked polymer of 3-O-methylmannose, regulates the fatty acid synthetase from Mycobacterium smegmatis by forming stoichiometric complexes with the long-chain acyl-CoA synthetase products. In agreement with previous proposals [Bloch, K. (1977) in Advances in Enzymology and Related Areas ... |
6994097 | DNA synaptase: an enzyme that fuses DNA molecules at a region of homology. | This paper describes an enzyme from Escherichia coli, and its purification to apparent homogeneity. The protein, which we call "DNA synaptase" and which may be representative of a class of enzymes, fuses double-stranded DNA molecules at a region of homology. In addition, the purified enzyme is able to catalyze the asso... |
6156231 | Calmodulin in mammalian nerve. | Calmodulin, a calcium-dependent regulatory protein has been isolated from mammalian nerve. The protein has similarities to the calcium-binding protein earlier shown to be transported at a fast rate in the nerve fibers. The implication is that calmodulin, which has been shown to be involved in various key cellular proce... |
6248235 | Formation and resolution of DNA catenanes by DNA gyrase. | We have discovered that DNA gyrase interlocks duplex DNA circles to form catenanes and resolves catenanes into component monomers. The reactions were inhibited by novobiocin and oxolinic acid and required ATP, Mg++ and spermidine. DNA sequence homology is not involved in catenation, since hybrid catenanes were formed e... |
7381745 | Stoichiometric model of alpha-cyclodextrin complex formation. | The solubility, spectral, and kinetic methods were used to study complexing between alpha-cyclodextrin (ligand, L) and 3,5-dimethoxycinnamic acid, benzalacetone, and methyl cinnamate (substrates, S). In aqueous solution at 25 degrees and with an ionic strength of 0.01 M, the following stability constants were found (K1... |
6991475 | Phaseolotoxin transport in Escherichia coli and Salmonella typhimurium via the oligopeptide permease. | Phaseolotoxin [(N delta-phosphosulfamyl)ornithylalanylhomoarginine], a phytotoxic tripeptide produced by Pseudomonas syringae pv. phaseolicola that inhibits ornithine carbamoyltransferase, is transported into Escherichia coli and Salmonella typhimurium via the oligopeptide transport system (Opp). Mutants defective in o... |
6769048 | Biosynthesis of the pigments of life: formation of the macrocycle. | The organic nuclei of chlorophylls, haems, cytochromes and vitamin B12 are biosynthesised from a single tetrapyrrolic intermediate which has an unexpected, rearranged structure. The mechanism of biosynthesis of this key intermediate has now been characterised in detail. Some of the information thereby obtained is also ... |
6989947 | The role of specific antibody in alternative complement pathway-mediated opsonophagocytosis of type III, group B Streptococcus. | The native capsular polysaccharide antigen of type III, group B Streptococcus contains a terminal sialic acid residue on each repeating unit that masks all end-group galactopyranose residues and prevents alternative pathway complement activation by adult human sera in the absence of type-specific antibody. The critical... |
6966315 | Quantitation of influenza virus antigens on infected target cells and their recognition by cross-reactive cytotoxic T cells. | Monoclonal antibody to type-A influenza virus matrix (M)-protein was used to quantitate the appearance of M-protein on abortively infected P815 cells. After 16 h of infection with different type-A viruses, only a low amount of M-protein appears on the surface of infected cells (approximately 10(3) site/cell) in contras... |
6892816 | Spectrin plus band 4.1 cross-link actin. Regulation by micromolar calcium. | A low-salt extract prepared from human erythrocyte membranes forms a solid gel when purified rabbit muscle G- or F-actin is added to it to give a concentration of approximately 1 mg/ml. This extract contains spectrin, actin, band 4.1, band 4.9, hemoglobin, and several minor components. Pellets obtained by centrifugatio... |
7372708 | Oversized flagellar membrane protein in paralyzed mutants of Chlamydomonas reinhardrii. | A mutant strain of Chlamydomonas reinhardtii is shown to possess an oversized flagellar membrane protein. The mutant has paralyzed flagella, is temperature sensitive for flagellar assembly, and has an abnormal axonemal protein composition. All phenotypes appear to derive from a single Mendelian mutation, and genetic an... |
6445751 | Characterization of medium inorganic phosphate-water exchange catalyzed by sarcoplasmic reticulum vesicles. | Effects of temperature, Ca2+, and ATP on the extent and characteristics of the medium Pi in equilibrium HOH exchange catalyzed by sarcoplasmic reticulum ATPase are reported. Measurements of the patterns of [18O]Pi species formed from highly labeled [18O]Pi show that a single catalytic pathway is involved in the rapid ... |
6246508 | DNA gyrase action involves the introduction of transient double-strand breaks into DNA. | DNA gyrase from Escherichia coli, in the presence of ATP, can both separate catenated DNA circles and unknot knotted DNA. Both these reactions require passage of a DNA segment through a transient double-strand break in DNA. Evidence that transient double-strand breaks are also involved in the supercoiling and relaxing ... |
6990016 | Structure and functions of the bacteriophage P22 tail protein. | The product of gene 9 (gp9) of Salmonella typhimurium bacteriophage P22 is a multifunctional structural protein. This protein is both a specific glycosidase which imparts the adsorption characteristics of the phage for its host and a protein which participates in a specific assembly reaction during phage morphogenesis.... |
7372574 | Structure of the regular surface layer of Sporosarcina ureae. | Optical diffraction and computer image processing of electron micrographs were employed to analyze the structure of the regular surface layer of Sporosarcina ureae at high resolution. Negatively stained preparations of regular surface layer fragments showed two types of tetragonal pattern, each having p4 symmetry in pr... |
6768387 | Chloroplast biogenesis. XXIX. The occurrence of several novel chlorophyll a and b chromophores in higher plants. | With the use of low temperature spectrofluorometry and matrix calculations it was demonstrated that the chlorophyll a pool of higher plants is made up of four different chlorophyll a chromophores. The latter were segregated by high pressure liquid chromatography on a silica column. They were designated Chl a (E432 F664... |
16592802 | Cyanobacterial phycobilisomes: Selective dissociation monitored by fluorescence and circular dichroism. | Phycobilisomes are supramolecular assemblies of phycobiliproteins responsible for photosynthetic light collection in red algae and cyanobacteria. They can be selectively dissociated by reduction of temperature and buffer concentration. Phycobilisomes isolated from Fremyella diplosiphon transfer energy collected by C-ph... |
16592795 | Self-assembled chlorophyll a systems as studied by californium-252 plasma desorption mass spectroscopy. | Self-assembled chlorophyll a and pheophytin a systems in thin solid films have been studied by (252)Cf plasma desorption mass spectrometry (PDMS). The (252)Cf-PDMS spectra of these films show monomer cation and anion molecular ions, ions of molecular aggregates, and positive and negative ion fragmentation patterns aris... |
7260839 | Therapy for metastatic colorectal carcinoma with a combination of methyl-CCNU, 5-fluorouracil vincristine and streptozotocin (MOF-Strep). | Seventy-seven previously untreated patients with measurable metastatic colorectal carcinoma were treated with a combination of methyl-CCNU, 5-fluorouracil (5-FU), vincristine and streptozotocin (MOF-Strep). The treatment schedule consisted of methyl-CCNU, 30 mg/m2 for 5 consecutive days q 10 weeks; 5-FU, 300 mg/m2 IV f... |
6155818 | [Periodic macromolecule syntheses in synchronized cultures of species belonging to the "Rhodococcus" genus ("Rhodochrous" group) (author's transl)]. | The synthesis of total proteins, total RNA and DNA in exponential synchronous cultures of species belonging to the Rhodococcus genus (Nocardia restricta and N. canicruria) has been studied by chemical methods and pulsed incorporations of labelled precursors in the acid-insoluble fraction. The replication of DNA is disc... |
6990411 | There is a correlation between the DNA affinity and mutagenicity of several 3-amino-1-methyl-5H-pyrido[4,3-b]indoles. | 3-Amino-1-methyl-5H-pyrido[4,3-b]indole, previously reported to be a component of tryptophan pyrolysates, is an intensely mutagenic compound requiring microsomal activation for expression of mutagenicity. We have found that this species and several synthetic analogs interact noncovalently with calf thymus DNA, as judge... |
6767708 | Development of Stigmatella aurantiaca: effects of light and gene expression. | Stigmatella aurantiaca, a gliding, gram-negative bacterium, exhibits complex developmental changes upon starvation. In the light the cells aggregate and develop multicellular fruiting bodies with stalks and sporangia within 20 h. Between 23 and 27 h, sonication-resistant myxospores are synchronously formed inside the s... |
7364726 | Polymethylpolysaccharide synthesis in an ethionine-resistant mutant of Mycobacterium smegmatis. | Mutants of Mycobacterium smegmatis were selected for resistance to ethionine in an effort to obtain methylation-defective strains that were altered in their ability to make methylmannose polysaccharides (MMP) or methylglucose lipopolysaccharides. Two methods were developed for the detection of MMP in cell extracts to a... |
6987326 | Molecular characterization of receptor binding proteins and immunogens of virulent Treponema pallidum. | Receptor binding proteins of Treponema pallidum were identified by incubation of [35S]methionine-labeled, soluble T. pallidum preparations with formaldehyde-fixed HEp-2 cells. Three major treponemal proteins (bands 1--3) that avidly bound to the eucaryotic cell surface were detected by sodium dodecylsulfate-polyacrylam... |
6986410 | Resistance of gram-negative bacteria to purified bactericidal leukocyte proteins: relation to binding and bacterial lipopolysaccharide structure. | The sensitivity or resistance of gram-negative bacteria to antibacterial systems appears to be related to the length of the saccharide chain of the bacterial envelope lipopolysaccharides (LPS). To explore this relationship further, we made use of two bactericidal, membrane-active cationic proteins, recently purified to... |
6255449 | Mechanism of 3' to 5' exonuclease associated with phage T5-induced DNA polymerase: processiveness and template specificity. | T5-induced DNA polymerase has an associated 3' to 5' exonuclease activity. Both single-stranded and duplex DNA are hydrolyzed by this enzyme in a quasi-processive manner. This is indicated by the results of polymer-challenge experiments utilizing product analysis techniques. Due to the quasi-processive mode of hydrolys... |
7189754 | Identification of microtubule-associated proteins in the meiotic spindle of surf clam oocytes. | Meiotic spindles isolated from surf clam oocytes to morphological purity are biochemically complex, consisting of many polypeptides. These proteins fall into two classes: (a) polypeptides that are apparently cytoplasmic proteins and are not specifically associated with the spindle; and (b) polypeptides that are specifi... |
6991420 | Binding of streptococcal antigens to muscle tissue in vitro. | Antigens extracted from cells of Streptococcus pyogenes T6 and Streptococcus mutans strains AHT, BHT, 10449, OMZ175, and K1R adsorbed to the sarcolemmal sheath of cardiac muscle cells in vitro. Similar preparations from S. salivarius, S. sanguis, Staphylococcus aureus, and Lactobacillus casei had weak or negligible tis... |
7370192 | Predictable "individual differences" in uptake and excretion of gases and lipid soluble vapours simulation study. | A five-compartment pharmacokinetic model with two excretory pathways, exhalation and metabolism, based on first order kinetics is used to outline the effect of body build, pulmonary ventilation, and lipid content in blood on uptake, distribution, and clearance of low solubility gases and lipid soluble vapours during an... |
6767694 | Separation and properties of the cytoplasmic and outer membranes of vegetative cells of Myxococcus xanthus. | We have developed methods for separating the cytoplasmic and outer membranes of vegetative cells of Myxococcus xanthus. The total membrane fraction from ethylenediaminetetraacetic acid-lysozyme-treated cells was resolved into three major fractions by isopycnic density centrifugation. Between 85 and 90% of the succinate... |
6245055 | Mutation in the crp gene of Salmonella typhimurium which interferes with inducer exclusion. | A mutation in the crp gene of Salmonella typhimurium is described which overcame the defects of ptsHI deletion mutants for growth on a number of nonphosphotransferase system compounds. This mutation abolished inducer exclusion in a leaky ptsI mutant. The possible implications for the mechanism of inducer exclusion are ... |
6444941 | Periplasmic maltose-binding protein confers specificity on the outer membrane maltose pore of Escherichia coli. | ompB mutants of Escherichia coli K-12 are markedly deficient in porin in their outer membrane. This results in a decreased rate of uptake for many substrates: the maltose pore (lambda receptor) can in some circumstances, in the absence of the periplasmic maltose-binding protein, compensate for the consequent defects in... |
6928690 | Electron microscope study of the kinetics of the fiber-to-crystal transition of sickle cell hemoglobin. | The intermediates and the rate-limiting step in the crystallization of deoxygenated sickle hemoglobin have been determined by a kinetic study with the use of electron microscopy. In slowly stirred solutions of deoxygenated hemoglobin S [Pumphrey, J. & Steinhardt, J. (1977) J. Mol. Biol. 112, 359--375], the sequential a... |
7359318 | trans-Cinnamic acid--alpha-cyclodextrin system as studied by solubility, spectral, and potentiometric techniques. | Complex formation in aqueous solutions of trans-cinnamic acid or trans-cinnamate ion (the substrate, S) and alpha-cyclodextrin (the ligand, L) can be described quantiatively as the 1:1 and 1:2 complexes, SL and SL2. The solubility, spectral, and potentiometric data over a wide range of ligand concentrations yielded con... |
6102083 | Adenosine triphosphatase activity of cutaneous nerve fibers. | The histochemical study of Mg++-activated adenosine triphosphatase (Mg++-ATPase) activity was carried out on the peripheral nerves of mouse digital skin by light and electron microscopy. Under the light microscope, the ATPase activity was clearly demonstrated on the nerve fibers as a fine network in the subepidermal re... |
16592774 | Comparison of rotational barriers of related diphenylmethyl anions and cations studied by C NMR spectroscopy: Mechanistic and structural considerations. | The rotational barriers of diphenylmethyl anions and cations were measured through their temperature-dependent (13)C NMR spectra. The ground state structures were found to possess a symmetrical propeller nature. The mechanism for phenyl rotation involves a nonsynchronous process, in which in the transition state one ri... |
7349009 | Biomechanics of vascular occlusion in neurosurgery. | Principle factors involved in effective vascular occlusion were identified and incorporated into a computer program designed to calculate the minimal occlusion force (MOF) in accordance with a modified version of Laplace's law. In vivo, the carotid arteries of 14 guinea pigs were occluded for one hour at an experimenta... |
Subsets and Splits
No community queries yet
The top public SQL queries from the community will appear here once available.