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172739 | The quantitative measurement of rotational motion of the subfragment-1 region of myosin by saturation transfer epr spectroscopy. | According to current models of muscle contraction (Huxley, H. E., Science 164: 1356-1366 [1969]), motion of flexible myosin crossbridges is essential to the contractile cycle. Using a spin-label analog of iodoacetamide bound to the subfragment No. 1 (S1) region of myosin, we have obtained rotational correlation times (... |
127891 | Calcium regulation of cardiac myofibrillar activation: effects of MgATP. | In 2 mM MgATP, 0.08 ionic strength and 1 mM free Mg++ cardiac myofibrils bound 3.5 nmoles Ca/mg protein at maximal ATPase activation. Significant amounts of Ca were also bound to cardiac myosin with these same conditions. By subtraction of this myosin-bound Ca we obtained an estimate of 4 moles Ca bound per mole of myo... |
1105006 | On the enthalpy of binding of ADP to heavy meromyosin. | The binding of ADP to heavy meromyosin has been studied by microcalorimetry. Minute amounts of myokinase interfere with binding measurements, but by selection of appropriate conditions, we can estimate that the value of the apparent deltaHbinding lies between - 1.0 and - 3.0 kcal per mole of ADP bound (0.3 M KC1, 2 mM ... |
127890 | Interaction of myosin and paramyosin. | The interaction of myosin and paramyosin was investigated by enzymological and ultrastructural techniques. The actin-activated Mg+2 ATPase of rabbit skeletal muscle myosin can be inhibited by clam adductor paramyosin. Both proteins must be rapidly coprecipitated to form filaments for this inhibition. Slowly formed cofi... |
172738 | Intermediate complex of ATP hydrolysis and synthesis by muscle proteins. | Myosin catalyzed exchange between 32Pi and ATP in reaction medium during its enzymatic hydrolysis of ATP only by a very small amount. Addition of actin increased to a great extent the rate of incorporation of 32Pi in the presence of Mg. Glycerinated smooth muscle fibers also exhibited the ability to exchange 32Pi and A... |
127887 | The binding of Mn2+ and ADP to myosin. | The metal ion requirement of myosin-ADP binding was investigated by use of Mn2+. Mn2+ binds to two sets of noninteracting sites on myosin which are characterized by affinity constants of 10(6) and 10(3), M(-1) at 0.016 M KCl concentration. The maximum number of sites is 2 for the high affinity and 20-25 for the low aff... |
172737 | Transient kinetic and isotopic tracer studies of the myosin adenosine triphosphatase reaction. | From transient kinetic studies of the Mg2+-dependent adenosine triphosphatase of myosin subfragment 1, prepared from rabbit skeletal muscle, a seven-step mechanism has been proposed. Features of this mechanism include two-step processes for ATP and ADP binding in which the binary complex isomerizes in addition to a rap... |
1195743 | Conformational flexibility and structure of creatine kinase. | The structural flexibility of creatine kinase has been investigated with the covalent hydrophobic probe 2-[4'-(2"-iodoacetamido) phenyl] aminonaphthalene-6-sulfonic acid (IAANS) which reacts at vastly different rates with the two subunits to give a protein conjugate with fluorescence characteristic of reaction with a s... |
172736 | Birefringence changes in vertebrate striated muscle. | The changes in birefringence in the rigor to relax transition of single Triton-extracted rabbit psoas muscle fibers have been investigated. The total birefringence of rigor muscle fibers was dependent on sarcomere length and ranged from (1.46 +/- 0.08) X 10(-3) to (1.60 +/- 0.06) X 10(-3) at sarcomere lengths from 2.70... |
1195742 | Heat production and metabolism during the contraction of mammalian skeletal muscle. | Methods are described whereby initial processes of muscular contraction may be investigated in a mammalian preparation, the soleus muscle of the rat. Conditions are chosen so that recovery is avoided. An isometric tetanus is investigated and an energy balance sheet is drawn up. It is found that there is more heat evolv... |
1105005 | Segmental flexibility in the myosin molecule: evidence from binding studies of myosin fragments with actin. | From comparative studies of the association with polymeric actin of the bifunctional species heavy meromyosin and its monofunctional constituents, information about the relative freedom of these paired elements can be derived. An isotherm for the former binding process is presented which involves, as an experimentally ... |
127886 | Time-dependent fluorescence depolarization and lifetime studies of myosin subfragment-one in the presence of nucleotide and actin. | Time-dependent fluorescence depolarization and lifetime studies have been made on myosin subfragment 1 to obtain information about mobility changes and dye environment changes when different nucleotides are added. Data are reported for static and actively hydrolyzing systems containing G- and F-actin. Preliminary data ... |
127885 | Isotopic probes of catalytic steps of myosin adenosine triphosphatase. | A new approach to the direct estimation of the value of the off constant for dissociation of ATP from myosin subfragment 1 (S1) has been developed. From measurements of the extremely slow rate of release of [32P] - ATP formed from 32P(i) by S1 catalysis and the amount of rapidly formed [32P] - ATP tightly bound to S1, ... |
127884 | The bound nucleotide of actin. | The extent of actin polymerization has been studied for samples in which the bound nucleotide of the actin was ATP, ADP, or an analog of ATP that was not split (AMPPNP). The equilibrium constants for the addition of a monomer to a polymer end were determined from the concentration of monomer coexisting with the polymer... |
172735 | Electron paramagnetic resonance and nanosecond fluorescence depolarization studies on creatine-phosphokinase interaction with myosin and its fragments. | Recent reports in the literature have indicated a physical association of creatine-phosphokinase (CPK) with the tail portion of the myosin molecule. The present paper describes further studies on the interaction of CPK with myosin and myosin fragments, using the techniques of electron paramagnetic resonance (EPR) and n... |
127883 | Structural changes in myosin during contraction and the state of ATP in the intact frog muscle. | The reactivity of myosin to [14C]-labeled N-ethylmaleimide ([14C]NEM) or to tritium was determined in functionally different frog muscles. The incorporation of [14C]NEM into myosin decreased during isotonic or isometric contractions, as compared to resting muscle. The cysteine residues which were protected during contr... |
127882 | An activation mechanism for ATP cleavage in muscle. | Evidence for a proposed activation mechanism is summarized. The low rate of ATP cleavage in the resting state of muscle is considered to result from the formation of a stable ring structure involving the two essential sulfhydryl groups on each myosin head and MgATP. Activation is thought to occur by interaction of acti... |
1189815 | [The supramolecular organization of oxyhemoglobin in erythrocytes. A small-angle x-ray scattering study]. | From X-ray scattering diagrams of concentrated solutions of hemoglobin the pair-correlation function of the molecules is calculated. At a concentration of 324 g/l the distance between neighbouring molecules amounts to 65 A. The number of direct neighbours of one molecule is 9. The pair-correlation function cannot be de... |
171521 | Magnetic resonance and kinetic studies of the mechanism of membrane-bound sodium and potassium ion- activated adenosine triphosphatase. | EPR and water proton relaxation rate (1/T1) studies of partially (40%) and "fully" (90%) purified preparations of membrane-bound (Na+ + K+) activated ATPase from sheep kidney indicate one tight binding site for Mn2+ per enzyme dimer, with a dissociation constant (KD = 0.88 muM) in agreement with the kinetically determi... |
127090 | Crosslinking studies on the Ca2+, Mg2+-activated ATPase of Escherichia coli. | Crosslinking of membrane proteins of Escherichia coli with dithiobis (succinimidyl propionate) (DSP) resulted in loss of several enzyme activities including the Ca2+, Mg2+-activated ATPase. This enzyme was crosslinked by DSP to the membrane and was not released by dialysis at low ionic strength in the absence of dithio... |
127089 | The possible role of tightly bound adenine nucleotides in oxidative and photosynthetic phosphorylation. | The tightly bound nucleotides of the beff-heart mitochondrial ATPase are released during cold inactivation followed by ammonium sulfate precipitation. During incubation at 0 degrees C the sedimentation coefficient (S20W) of the ATPase first declines from 12.1S to 9S. Prolonged incubation or precipitation with ammonium ... |
1237768 | Effect of crosslinking on mitochondrial structure and function. | Rat liver mitochondria were treated with ethylacetimidate and methylbutyrimidate, monofunctional imidates, and with dimethylsuberimidate, a bifunctional imidate, and the effects on structure and function studied. Mitochondria treated with 5 mM dimethylsuberimidate or greater did not respond osmotically when placed in d... |
127088 | Studies of substructure and tightly bound nucleotide in bacterial membrane ATPase. | Highly purified preparations of Streptococcus faecalis ATPase contain a similar but inactive protein detected by prolonged polyacrylamide gel electrophoresis. The inactive protein appears to arise by proteolytic cleavage of the major subunits in the enzyme. By use of a new technique, subunit analysis in SDS gels was pe... |
1237767 | The effects of ADP on reverse electron flow and the oxygen exchange reactions catalyzed by bovine heart muscle submitochondrial particles. | 1,N6-Ethenoadenosine diphosphate (epsilon-ADP) inhibits reverse electron flow (succinate leads to NAD+ driven by ATP) by competing with ATP, in contrast to ADP which we have shown previously to be a noncompetitive inhibitor. From these and other data it is concluded that the noncompetitive inhibition noted with ADP res... |
127087 | Partial purification of active delta and epsilon subunits of the membrane ATPase from escherichia coli. | We have partially purified active delta and epsilon subunits of the E. coli membrane-bound Mg2+-ATPase (ECF1). Treating purified ECF1 with 50% pyridine precipitates the major subunits (alpha, beta, and gamma) of the enzyme, but the two minor subunits (delta and epsilon), which are present in relatively small amounts, r... |
171520 | Studies of the oligomycin-sensitive ATPase from yeast mitochondria. Reconstitution of ATP-32Pi exchange in the presence of phospholipids. | A purified preparation of the oligomycin-sensitive ATPase from yeast mitochondria has been shown to elicit an oligomycin- and uncoupler-senstitive ATP-32Pi exchange in the presence of phospholipids. Reconstitution was normally achieved by dialysis of an ATPase-phospholipid-cholate mixture. Following this procedure, ves... |
127086 | Purification and properties of membrane-bound coupling factor-latent ATPase from Mycobacterium phlei. | The membrane bound coupling factor-latent ATPase was solubilized from the membrane vesicles of Mycobacterium phlei by using 0.25 M sucrose or low ionic strength buffer. Purification of the solubilized enzyme by use of Sepharose-ADP conjugate gel yielded a homogenous preparation of latent ATPase which was purified about... |
127085 | Interaction of homogeneous mitochondrial ATPase from rat liver with adenine nucleotides and inorganic phosphate. | Mitochondrial ATPase from rat liver mitochondria contains multiple nucleotide binding sites. At low concentrations ADP binds with high affinity (1 mole/mole ATPase, KD = 1-2 muM). At high concentrations, ADP inhibits ATP hydrolysis presumably by competing with ATP for the active site (KI = 240-300 muM). As isolated, mi... |
127084 | Exploring sites on mitochondrial ATPase for catalysis, regulation, and inhibition. | Evidence is presented that mitochondrial ATPase has two types of sites that bind adenine nucleotides. The catalytic site, C, binds the substrates ATP, GTP, or ITP and the inhibitor guanylyl imidodiphosphate (GMP-PNP). A second type of site, R, binds ATP, ADP, adenylyl imidodiphosphate (AMP-PNP), and the chromium comple... |
1102805 | Energy conservation and uncoupling in mitochondria. | Energy conservation and uncoupling in mitochondria are examined in the light of three important new findings: (a) Studies with the photoaffinity-labeling uncoupler 2-azido-4-nitrophenol have shown that mitochondria contain a specific uncoupler binding site (apparently a polypeptide of Mr = 30,000 +/- 10%). (b) This sit... |
1152470 | Oxidation of lipids and membranes II: Effects of oxidants on cerebral white matter homogenates. | Bovine cerebral white matter homogenates were oxidized by various oxidizing solutions of equal molarity and subsequently extracted with water. Most of the oxidants tested (K-dichromate, FeCL3, H2O2, O2, and chloroperbenzoic, ascorbic, performic, and periodic acids) rendered the various myelin constituents less extracta... |
1152469 | Oxidation of lipids and membranes I: in vitro formation of peroxidative lipid polymers. | Fluorescent polymers were obtained by oxidizing partly emulsified linolenic acid with different oxidants. The speed of formation of polymers differed for the various oxidants, and the difference was not a simple function of the oxidation potential. The speed of polymerization also depended on the nature of the emulsion... |
168435 | Interaction of the 5'-ends of 28S RNA in dimerization of hamster ribosomes. | Free ribosomes extracted from hamster cells and 28S RNA purified from these ribosomes are known to form dimers. We find that spleen phosphodiesterase inhibits ribosomal dimer formation, but only when a free 5'-hydroxyl end group, produced by the action of alkaline phosphatase, is present. Hence, formation of dimer ribo... |
1152468 | Hemocyanin - antibody labeling of phodopsin in mouse retina for a scanning electron microscope study. | To reveal the presence of rhodopsin on the surface of the mouse retina, a scanning electron microscope study of the immunolabeling of rhodopsin was attempted. The glutaraldehyde-fixed mouse retina was treated first with rabbit antibodies specific against bovine rhodopsin and then with hemocyanin-labeled goat antibodies... |
1152467 | Radioiodination of the envelope proteins of Newcastle disease virus. | Lactoperoxidase-catalyzed iodination selectively labels the two glycoproteins (VP1 and VP2) of Newcastle disease virus. The low-molecular-weight, nonglycosylated major viral protein, VP6, was not iodinated in the intact virus but was iodinated in disrupted virions, suggesting a localization on the inner, rather than th... |
1152466 | The formation of filamentous structures from iodinated neurotubules. | The porcine neurotubule and its basic subunit were found to be modified in vitro by iodination of amino acids (principally tyrosine) using lactoperoxidase. Iodide ion, H2O2, or lactoperoxidase singly or in any pairwise combination had virtually no effect on neurotubules. However, when all three reagents were present, p... |
1152465 | Assembly of the tail of bacteriophage T4. | The protein products of at least 21 phage genes are needed for the formation of the tail of bacteriophage T4. Cells infected with amber mutants defective in these genes are blocked in the assembly process. By characterizing the intermediate structures and unassembled proteins accumulating in mutant-infected cells, we h... |
1152464 | Interactions between collagen chains and fiber formation. | The temperature-dependent dissociation of neutral salt-soluble collagen into its component chains was measured in 0.6-1.6 M urea solutions at pH 7.3. The temperature-dependent association of the same radioactively labeled collagen into fibers was measured in 0-0.4 M urea solutions, pH 7.3. The effect of urea on the tem... |
239275 | On the physiological functions of teichoic acids. | The choline-containing teichoic acids of pneumococci can be modified by biosynthetic replacement of the choline residues with certain structural analogues, such as ethanolamine (EA) or the N-monomethyl-(MEA) and N-dimethyl-(DEA) amino derivatives of ethanolamine. Cells containing such analogues in their teichoic acids ... |
1149141 | [Pathology in the current scientific and technological revolution]. | Scientific and technological development in morphological disciplines has created an creates unheard of possibilities for scientific research and practical examination of morphological changes and in its consequences has contributed also in a substantial way to a change in fundamental views on the subcellular and supr... |
1095567 | Properties of membrane-associated sialyltransferase of Escherichia coli. | Membrane-associated sialyltransferase complexes in Escherichia coli K-235 can be dissociated by lipid deletion and reassembled by the addition of undecaprenyl phosphate, a unique membrane-bound lipid coenzyme. Following disruption of the cells by pressure disintegration and centrifugal fractionation, the sialyltransfer... |
235654 | The reaction of chemical probes with the erythrocyte membrane. | Trinitrobenzenesulfonate (TNBS), fluorodinitrobenzene (FDNB) and suberimidate have been reacted with intact human erythrocytes. TNBS does not penetrate the cell membrane significantly at 23 degrees C in bicarbonate-NaCl buffer, pH 8.6, as estimated by the labeling of the N-terminal valine of hemoglobin. Hence, under th... |
1120109 | Comparison of the resonance Raman spectra of carbon monoxy and oxy hemoglobin and myoglobin: similarities and differences in heme electron distribution. | With 441.6-nm excitation, which is near the Soret band, we observe that the resonance Raman spectra of hemoproteins contain not only the bands between 650 and 1700 cm-1 which arise from vibrations of the conjugated macrocycle, but also bands below 650 cm-1, some of which involve vibrations of the iron pyrrole-nitrogen ... |
1090936 | Complementation in cytoplasmic petite mutants of yeast to form respiratory competent cells. | Complementation has been observed in cytoplasmic respiratory deficient yeast cells (petites) to yield respiratory competent diploids. This successful demonstration depended on the use of spontaneous petites of recent origin and on crosses involving all possible apirwise combinations between the many different petite is... |
235127 | A kinetic study in vitro of the reoxidation of interchain disulfide bonds in a human immunoglobulin IgGLk. Correlation between sulfhydryl disappearance and intermediates in covalent assembly of H2L2. | After reduction by dithiothreitol and removal of the reductant by molecular sieve chromatography, the four interchain disulfide bonds of the human IgGlk protein Fro reoxidize in the presence of oxygen and trace metal ions. The six molecular components of the reoxidation--L (light chain), H (heavy chain), HL, H2, H2L, H... |
1054500 | Recombinant DNA molecules of bacteriophage phi chi174. | Phi chi174 DNA structures containing two different parental genomes were detected genetically and examined by electron microscopy. These structures consisted of two monomeric double-stranded DNA molecules linked in a figure 8 configuration. Such DNA structures were observed to be formed preferentially in host recA+ cel... |
122932 | Structural relationship between "glutamic acid" and "lysine" forms of human plasminogen and their interaction with the NH2-terminal activation peptide as studied by affinity chromatography. | Urokinase digestion of maleinated plasminogen results in cleavage of the single peptide bond Arg-68-Met-69, which is one of the bonds normally cleaved during the first step of the activation procedure. The inactive intermediate compound formed in this way was subjected to NH2-terminal amino acid sequence analysis, whic... |
45845 | An ultrastructural examination of the role of cell membrane surface coat material during neurulation. | Data from neural crest cultures indicate that cell surface coat material (CSM) is directly involved in cellular migration and events surrounding differentiation. To investigate whether the CSM also has a morphogenetic role, embryos of the amphibian Ambystoma maculatum were examined ultrastructurally throughout the stag... |
137887 | Cytochemical characterization of the myoepithelial cells in palatine glands. | Myoepithelial cells of rat and mouse palatine glands are similar in fine structural appearance to those of other exocrine glands and smooth muscle cells. Myoepithelial cells reveal fibrils, and vesicular structures comparable to pinocytic or surface vesicles of smooth muscle cells. Lanthanum-impregnated preparations of... |
137719 | The binding of nucleotides and bivalent cations to the calcium-and-magnesium ion-dependent adenosine triphosphatase from rabbit muscle sarcoplasmic reticulum. | The binding of MgATP to purified Ca2+Mg2+-dependent adenosine triphosphatase from rabbit muscle sarcoplasmic reticulum was studied by using a flow-dialysis method. Phosphoryl-enzyme formation and catalytic activity were also measured, and all three processes demonstrated negative co-operativity, with half-saturation of... |
1069991 | Brain tubulin polymerization in the absence of "microtubule-associated proteins". | Pure tubulin dimer, purified by phosphecellulose chromatography to remove microtubule associated proteins, can be assembled into microtubules in the presence of dimethyl sulfoxide. The surfaces of such microtubules are devoid of filamentous material. The reaction is rapid and strongly dependent on protein concentration... |
16592367 | Covalently linked chlorophyll a dimer: A biomimetic model of special pair chlorophyll. | The synthesis of a covalent dimer of chlorophyll a which possesses properties strikingly similar to those exhibited by P700 special pair chlorophyll in vivo is described. The covalent dimer is characterized by several spectroscopic techniques. Hydrogen bonding nucleophiles, such as water, primary alcohols, and primary ... |
12149 | The mechanism of reassembly of immunoglobulin G. | The noncovalent interaction of light (L) chain with heavy (H) chain or Fd isolated from a human myeloma protein Jo (IgG1, kappa) was studied by following circular dichroic (CD) change at 235 nm. The dimerization constants of Jo-L chain determined by measuring the CD change at 293 nm with protein concentration showed th... |
1069288 | Collagen fibrillogenesis: intermediate aggregates and suprafibrillar order. | Polymerization of collagen in vitro has been studied with the electron microscope at early time points of fibril assembly. We have found morphologically distinct stages of aggregation, which we suggest represent successive steps in fibril formation. Linear growth of the fibril appears to occur by the tandem addition of... |
186777 | Regulation of dopamine stimulation of striatal adenylate cyclase by an endogenous Ca++ -binding protein. | Membranes of rat caudate nucleus contain a dopamine-dependent adenylate cyclase [ATP pyrophosphate-lyase (cyclizing), EC 4.6.1.1] and a Ca++ binding protein that activates phosphodiesterase (3':5'-cyclic-AMP 5'-nucleotidohydrolase, EC 3.1.4.17). This activator can be released from the membranes by a phosphorylation wit... |
1069267 | Role of proteolytic enzymes in biological regulation (a review). | Many enzymes, hormones, and other physiologically active proteins are synthesized as inactive precursors (zymogens) that are subsequently converted to the active form by the selective enzymatic cleavage (limited proteolysis) of peptide bonds. The ultimate agency of activating enzymatic function is limited proteolysis, ... |
991817 | Biotransformations of pituitary luteinizing hormone in serum and urine. I. Association with serum components. | In the effort to elucidate the nature of luteinizing hormone (LH) in the circulation, studies in adult male rats have been conducted using a highly purified and well-characterized tritiated and methylated ovine pituitary LH, a derivative which retains full biological activity. Following an intravenous injection of the ... |
10957 | Solubilization, partial purification and radioassay for the intrinsic factor receptor from the ileal mucosa. | A macromolecule which binds intrinsic factor saturated with vitamin B12 has been solubilized from the guinea-pig ileum by homogenization followed by mechanical disruption without organic solvents or detergents. This intrinsic factor 'receptor' was further purified by precipitation with 30% saturated ammonium sulphate, ... |
1087159 | The fine structure of pulmonary contusion and the effect of various drugs. | The results of contusion were examined by electron and light microscopy in the lungs of rats. It was found that the results here were very similar to those elsewhere in the body, with a few minor modifications due to the unique structure of the lung. Densitometry of protein concentration and visual estimation of oedema... |
999640 | Stereospecific haem cleavage. A model for the formation of bile-pigment isomers in vivo and in vitro. | A new approach is suggested for an explanation of sterospecific haem degradation to biliverdin and bilirubin. A model is proposed in which an oxygen molecule, bound to the haem iron atom, attacks a methene-bridge carbon atom in an intramolecular reaction. Specificity of macrocyclic ring cleavage is explained on the bas... |
999630 | Subsite mapping of enzymes. Application of the depolymerase computer model to two alpha-amylases. | In the preceding paper (Allen and Thoma, 1976) we developed a depolymerase computer model, which uses a minimization routine to establish a subsite map for a depolymerase. In the present paper we show how the model is applied to experimental data for two alpha-amylases. Michaelis parameters and bond-cleavage frequencie... |
991229 | Innervation of the carotid body of the adult rat. A serial ultrathin section analysis. | The innervation of the carotid body of adult rats was studied by means of serial ultrathin sections. A single branching nerve fiber innervates 12 chief cells through several kinds of terminals (vesicle-containing, mitochondrial sack, and calyx-type) in en-passant and bouton forms.Two types of synaptic contacts between ... |
1068468 | Calorimetric studies of the in vitro polymerization of brain tubulin. | The enthalpy change for chain propagation in the polymerization of bovine tubulin has been studied directly by stopped-flow microcalorimetry at 17 degrees and 25 degrees, and found to be 0 +/- 1 kcal per mol of 6S tubulin dimer at both temperatures. Substantial heat evolution with a half-time of decay of approximately ... |
62361 | Human somatotropin: biological characterization of the recombinant molecule. | The recombinant hormone obtained by non-covalent interaction of the NH2-terminal 134 amino acid fragment with the COOH-terminal 51 amino acid fragment of the reduced-carbamidomethylated human somatotropin molecule is found to exhibit nearly full biological activity of the native hormone, as evidenced by the stimulation... |
1068446 | Carbon monoxide binding to pentacoordinate mercaptide-heme complexes: kinetic study on models for cytochrome P-450. | Mercaptide anions form exclusively penta-coordinate heme complexes [RS-heme] in polar and nonpolar solution over a wide range of mercaptide concentration. These complexes have a Soret peak at 408 nm and a formation constant of about 2.5 X 10(4) M(-1), and combine with CO to give a CO-cytochrome P-450 type spectrum. Kin... |
978794 | Multiplication of parvovirus LuIII in a synchronized culture system. IV. Association of viral structural polypeptides with the host cell chromatin. | Newly synthesized structural polypeptides of parvovirus LuIII, VP1 (62,000 daltons) and VP2 (74,000 daltons), were detected in nuclei of synchronized, infected HeLa cells at 11 to 12 h postinfection, i.e., after cells had passed through the S phase of the cell cycle. At this time, most of intranuclear viral polypeptide... |
978134 | Alternative pathway of complement: recruitment of precursor properdin by the labile C3/C5 convertase and the potentiation of the pathway. | In this study the physiological role of properdin and the differential subunit composition of the solid phase enzymes of the pathway have been explored. Cell-bound C3 and C5 convertase differ in their C3b requirement. Apparently one molecule of C3b is sufficient to allow formation of C3 convertase (C3b,B), whereas two ... |
10309 | The microsporidian spore invasion tube. The ultrastructure, isolation, and characterization of the protein comprising the tube. | The extrusion apparatus of the microsporidian parasitic protozoan Nosema michaelis discharges an invasion (or polar) tube with a velocity suitalbe for piercing cells and injecting infective sporoplasm. The tube is composed of a polar tube protein (PTP) which consists of a single, low molecular weight polypeptide slight... |
988028 | Reversible particle movements associated with unstacking and restacking of chloroplast membranes in vitro. | Freeze-fracture and freeze-etch techniques have been employed to study the supramolecular structure of isolated spinach chloroplast membranes and to monitor structural changes associated with in vitro unstacking and restacking of these membranes. High-resolution particle size histograms prepared from the four fracture ... |
184113 | Selective inhibition of osmotic water flow by general anesthetics to toad urinary bladder. | Vasopressin increases the permeability of the total urinary bladder, an analogue of the mammalian renal collecting duct, to water and small solutes, especially the amide urea. We have observed that three general anesthetic agents of clinical importance, the gases methoxyflurane and halothane and the ultrashortacting ba... |
963199 | Prediction of the conformation of the histones. | The secondary structures of the histones, H1, H2A, H2B, H3, and H4 have been predicted utilizing the predictive scheme of Chou and Fasman (Biochemistry 13:211, 222[1974]) and a new set of conformational parameters based on the X-ray data of 29 protein structures. The alpha-helical, beta-sheet, reverse beta-turns, and r... |
14713 | [Several physical aspects of intracellular energy transformation]. | Physical principles underlying the chemiosmotic hypothesis of membrane phosphorylation are analysed. The utilization of free energy determined by dydrogen ions concentration difference across the membrane for ATP synthesis requires ATP-synthetase to be an entropy machine able to perform work on account of heat. The che... |
61819 | Fluorescence-microscopical demonstration of a population of gastro-intestinal nerve fibres with a selective affinity for quinacrine. | A population of nerve fibres in the gastro-intestinal tract of mice showing a high affinity for quinacrine was revealed by fluorescence microscopy. Similar results were obtained in rats and guinea pigs. Whole-mounts of sheets of the smooth muscle layer following incubation in 10(-6)-10(-7) M quinacrine for 15-60 min re... |
9641 | Mechanism of uncoupling in mitochondria: uncouplers as ionophores for cycling cations and protons. | Classical uncouplers such as 2,4-dinitrophenol have been shown to be ionophores with the capability for transporting monovalent or divalent cations with equal efficiency. The conditions appropriate for the maximal expression of this ionophoric capability have been explored. Two critical factors are the polarity of the ... |
9640 | Supersaturation in sickle cell hemoglobin solutions. | The kinetic inhibition of the gelation of hemoglobin S is compared to the change in hemoglobin S soulbility, when the solubility is altered by carbon monoxide, pH, or urea. By means of a new technique, the delay time and the extent of gelation are measured on the same sample. They delay time, td, is found to be proport... |
61581 | Influence of phosphate on activity and stability of reverse transcriptase from avian myeloblastosis virus. | Activity of RNA-dependent DNA polymerase (RDDP) from avian myeloblastosis virus (AMV), either in purified form or in virus lysates, was increased by phosphorylation. Stability of RDDP in lysates buffered with phosphate was much greater (no loss of activity in 48 hours at 4 degrees) than that in lysates buffered with Tr... |
823385 | Thermodynamics of aging in Drosophila melanogaster. | The data on mortality kinetics and decline in functions reported in the preceding article are used to calculate temperature coefficients for the aging process(es) in Drosophila. Different values are found, according to the model chosen to account for the mortality kinetics. The respective implications of three equally ... |
963204 | Nuclear magnetic resonance measurement of skeletal muscle: anisotrophy of the diffusion coefficient of the intracellular water. | The anisotropy of the spin-diffusion coefficient Ds of water protons in skeletal muscle has been studied by pulsed NMR methods. The mid-portion of the tibialis anterior muscle of mature male rats was placed in a special sample holder by means of which the muscle fiber orientation theta relative to the diffusion directi... |
16592347 | Amine-catalyzed hydrolyses of cyclodextrin cinnamates. | Hydrolyses of beta-cyclodextrin cinnamate (betaCDC) and alpha-cyclodextrin cinnamate were catalyzed by amines such as 1,4-diazabicyclo(2.2.2)octane, triethylamine, quinuclidine, piperidine, diisobutylamine, and n-butylamine. The rate constant of hydrolyses of the betaCDC-amine complexes follows the order: 1,4-diazabicy... |
787007 | Convenient system for multiple screening of microbial carbohydrate metabolism. | A rapid technique for inoculating carbohydrate oxidation and fermentation media is described. This method employs 24-well tissue culture trays and a multi-inoculator. Other applications are discussed. |
1066692 | Polycation-induced assembly of purified tubulin. | Several different polycations have been found that can substitute for the microtubule-associated proteins, or tau factor, in facilitating assembly of tubulin that has been purified by ion exchange chromatography. In low concentrations of the polycation diethylaminoethyl-dextran, 7 mg of tubulin is pelleted per 1 mg of ... |
1009167 | [Change in the elastoviscosity of supramolecular DNA of sturgeon spawn after conservation with 4.5-5% NaCl]. | Elastoviscosity of supermolecular DNA of beluga, sevruga and sturgeon pawn 6 months after conservation with 4.5-5% NaCl was studied. It is shown that a positive relation exists between elastoviscosity of SM DNA and its gustatory qualities. Therefore the value of elastoviscosity of SM DNA may be used for testing the cha... |
185944 | Antiviral action and cellular toxicity of four thymidine analogues: 5-ethyl-,5-vinyl-, 5-propyl-, and 5-allyl-2'- deoxyuridine. | 5-Ethyl-, 5-vinyl-, 5-propyl-, and 5-allyl-2'-deoxyuridine (dUrd) had antiviral activity against herpes simplex type 1 and type 2 grown in HeLa TK(-) cells, in the order 5-vinyl-dUrd, 5-ethyl-dUrd, 5-propyl-dUrd, 5-allyl-dUrd, but they were inactive against a TK(-) mutant of herpes simplex type 1. The antiviral activit... |
982623 | [Determination of fibrin and fibrinogen split products by their anticoagulant activity]. | A new diagnostic method to determine fibrinogen and fibrin splitting products is based on the fact that high-molecular fragments acting as specific inhibitors of fibrin self-assembly compose these products. Fibrinogen and fibrin splitting products are detected and determined quantitatively by prolongation of coagulatio... |
184256 | Individual EPSPs produced by single triceps surae Ia afferent fibers in homonymous and heteronymous motoneurons. | 1. The individual EPSPs evoked by the action of single Ia fibers from cat triceps surae (MG, LG, SOL) were recorded in homonymous and heteronymous motoneurons innervating these same three muscles. 2. In general, Ia fibers projected to a greater percentage of homonymous than heteronymous motoneurons. One class of Ia aff... |
962859 | Types I and II collagens in intervertebral disc. Interchanging radial distributions in annulus fibrosus. | Intervertebral disc is a highly specialized cartilaginous tissue, containing two genetic types of collagen (I and II). Analysis of peptides from a CNBr digest of collagen showed that the proportions of I and II varied gradually and inversely across pig annulus fibrosus, with exclusively type I at the extreme outer edge... |
183514 | Agonist and antimineralocorticoid activities of spirolactones. | To investigate the mechanism of action of antimineralocorticoids, a series of spirolactone analogues was evaluated for both mineralocorticoid antagonist and agonist activity. Antagonist activity was assessed by inhibition of aldosterone stimulated sodium transport employing toad bladder short-circuit current (SCC) meas... |
182237 | Resonance raman studies of a c type algal cytochrome. Deuterium shifts and a comparison with mammalian cytochrome c. | A c type cytochrome isolated from Synechococcus lividus grown on water and 2H2O media, has been studied by resonance Raman spectroscopy. The spectra were taken on the oxidized and reduced protein with excitation within the Soret band at 441.6 nm to determine whether individual resonance Raman bands of the heme shift up... |
948988 | Neural damage in the guinea pig cochlea after noise exposure. A light microscopic study. | Neural damage produced by exposure to 8 kHz octave-band noise was studied by light microscopy in guinea pigs. Abnormal nerve endings were found beneath both inner and outer hair cells within 24 hours after exposure at either 118 or 120 dB SPL. In areas where the organ of Corti was destroyed degeneration of myelinated n... |
949858 | A syndrome of generalized elastic fiber deficiency with leprechaunoid features: a distinct genetic disease with an autosomal recessive mode of inheritance. | Three male infants with generalized elastolysis and leprechaunoid features from two related and consanguineous parents of Italian origin died in the first year of life following severe cardio-pulmonary complications. While these children showed a decrease in elastic fibers, no degeneration was noted and histochemical a... |
947403 | Degranulation and abnormal bactericidal function of granulocytes procured by reversible adhesion to nylon wool. | Granylocyte bactericidal capacity, chemotaxis, hexose monophosphate shung activity (before and after phagocytic stimulus), and quantitative nitroblue tetrazolium reduction and enzyme content were examined in cells obtained by filtration leukaphresis (FL) and continuous-flow centrifugation (CFC). A decrease in the bacte... |
938719 | Radiation damage in tripalmitin layers studied by means of infrared spectroscopy and electron microscopy. | Structural deteriorations in biomembranes, as inevitably induced while structural information is gathered by electron optical methods, were evaluated by infrared spectroscopy. Tripalmitin model membranes were irradiated with 100 keV-electrons in an electron microscope. The intensity decay of group vibrations over the d... |
1084403 | Properties of the antigen-specific suppressive T-cell factor in the regulation of antibody response of the mouse. III. Dual gene control of the T-cell-mediated suppression of the antibody response. | The antigen-specific suppressive T-cell factor of mice, which had previously been shown to be an I region gene product, could effectively suppress the in vitro secondary antibody response of spleen cells from syngeneic or H-2 compatible mouse strains but not that of H-2 incompatible strains. The identities among genes ... |
1001288 | Methoxyflurane nephropathy. | Investigations of methoxyflurane-induced nephrotoxicity in man have been extensively aided by the use of an animal model. To be of value the animal model must share similar metabolic pathways with man and have the same clinical manifestations of the diseases process. The Fischer 344 rat appears to meet these criteria. ... |
1085600 | [Study by gel electrophoresis, of alpha chains and of CNBr peptides of collagen from epiphyseal cartilage in chondrodysplasia]. | The alpha chains and the major CNBr - derived peptides of collagen of growth cartilage were studied in the following syndromes: thanatophoric dwarfism, pseudothanatophoric dwarfism, achondroplasia, pseudoachondroplasia, diastrophic dwarfism, metatropic dwarfism, Kniest disease, parastremmatic dwarfism, multiple exostos... |
781516 | Replication of small plasmids in extracts of Escherichia coli. | Sakakibara and Tomizawa (1974a) have described a soluble in vitro system that can carry the semi-conservative replication of the Co1 E1 plasmid. However, the usefulness of this system is restricted by its rapid inactivation during storage. This paper describes a stable soluble system prepared by freeze-thaw lysis of ch... |
778849 | Morphogenesis of the bacterial division septum: a new class of septation-defective mutants. | A new class of mutants of Salmonella typhimurium (lkyD mutants) are described. The mutants are defective in morphogenesis of the division septum, and are characterized by a failure of the outer membrane to invaginate despite normal ingrowth of the cytoplasmic membrane and murein layers of the growing septum. The cell e... |
18961905 | Gas-liquid chromatographic study of monosubstituted benzaldehyde isomers. | Monosubstituted benzaldehyde isomers have been studied quantitatively on nine stationary liquid phases of various physical and chemical characteristics and at different operating temperatures. Apiezon 1 + Bentone 34, dinonyl phthalate and di(2-ethylhexyl)sebacate are found to be selective for quantitative separation of... |
16592321 | New proposal for structure of special-pair chlorophyll. | A new model is proposed for the structure of the special pair of chlorophyll a molecules believed to correspond to the P700 species in green plants and algae. The proposed model, although admittedly speculative, is based upon exciton-theoretical considerations and on in vitro infrared and visible absorption spectra of ... |
940773 | Investigation of the mechanism of the synthesis of oligonucleotides. IX. 31P NMR spectra of the active dinucleotide derivatives and their analogs. | The interaction of 3'-O-acetyldithymidilate (pdTpdT(Ac)), thymidine-3',5'-diphosphate (pdTp) and thymidine-3'-phenyl-phosphate-5'-phosphate (pdTpPh) with 2,4,6-triisopropylbenzene sulphonyl chloride (TPS) and N,N'-dicyclohexylcarbodiimide (DCC) in pyridine and dimethylformamide (DMF) was studied by pulsed NMR spectrosc... |
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