bluuebunny/crossref_metadata_2025_split huggingface dataset:
Raman and infrared spectra, ab initio calculations and normal coordinate analysis of boranedimethyl sulfide
Authors: Chatterjee K. K. , Durig J. R. 
Published: May 2005

AbstractThe Raman spectra (3200‐40 cm−1) of liquid and solid boranedimethyl sulfide, (CH3)2SBH3, were recorded and depolarization data were obtained from the liquid. Additionally, the infrared spectrum (3200‐400 cm−1) of the liquid was obtained. A complete vibrational assignment is proposed based on depolarization data, group wavenumbers and relative intensities and it is supported by normal coordinate calculations. Ab initio calculations were carried out employing the RHF/3‐21G*, RHF/6‐31G* and MP2/6‐31G* basis sets to obtain the structural parameters, the fundamental wavenumbers and the intensities of the infrared bands. The calculated values are compared with the corresponding experimental quantities. The results are discussed and compared with similar quantities for some related molecules.
Raman optical activity of enantiomorphic single crystals
Authors: Lindner M. , Schrader B. , Hecht L. 
Published: May 2005

AbstractConventional Raman and incident circular polarization Raman optical activity (ROA) spectra are presented for the lattice vibrations of enantiomorphic pairs of optically active cubic crystals NaBrO3 and NaCIO3 in depolarized right‐angle scattering (65‐145 cm−1) and unpolarized backscattering (55‐200 cm−1). Since enantiomorphic cubic crystals are also piezoelectric owing to the lack of a centre of inversion, the degeneracy of their triply degenerate polar (infrared and Raman active) F phonons is partially lifted because of long‐range dipole‐dipole interactions. Therefore, non‐degenerate longitudinal and doubly degenerate transverse optical phonons can be separately observed in the ROA spectra.
Study of polarization CRS and polarization ICRS with application to benzena
Authors: Schaertel S. A. , Lee Duckhwan , Albrecht A. C. 
Published: May 2005

AbstractPassage from the microscopic third‐order optical polarizability tensor to the macroscopic third‐order susceptibility tensor elements in coherent Raman scattering (CRS: CARS and CSRS) is reviewed with appropriate orientation averaging for an isotropic medium. The results are applied to existing polarized CARS measurements for the 991 cm−1 vibration in benzene as a neat liquid [M. D. Levenson and N. Bloembergen, J. Chem. Phys. 60, 1323 (1974)] and also to new polarized interferometric data on the same system from a method called interferometric coherent Raman spectroscopy (ICRS; ICSRS in particular is used). Lineshape analysis of the CARS spectra seen in both the ZXXZ polarization (mildly dispersive) and the ZZZZ polarization (strongly dispersive) leads to ratios for the non‐resonant to resonant parts of the corresponding susceptibility elements. Thus X/X = 0.5 (from 0.3‐1.7) (a new result) and X/X = 0.042 + 0.002 (from Levenson and Bloembergen). It is shown that given one ratio, the second must be completely determined by the depolarization ratio from conventional Raman scattering. These same tensor element ratios are incorporated into ICSRS theory to produce polarized interferograms which qualitatively confirm the strikingly different patterns seen in the ZXXZ and ZZZZ polarized ICSRS experiments. On the quantitative level, agreement is less satisfactory.
Raman spectroscopic studies of silk
Authors: Edwards H. G. M. , Farwell D. W. 
Published: May 2005

AbstractThe Fourier transform Raman spectra of silk at several stages of its processing from raw natural and cultivated cocoons to woven fabric were obtained. The application of near‐infrared excitation to the recording of quality Raman spectra from bulk samples, including Russian and Chinese varieties, and from a single 10 μm fibre is demonstrated. Comprehensive vibrational assignments are made for silk and comparisons are made of wild and cultivated silks, bleached and unbleached de‐gummed varieties and inner and outer cocoon material.
Surface‐enhanced Raman spectroscopic investigations of thiazole orange derivatives using visible and near‐infrared excitation
Authors: Nissum M. , Nielsen O. Faurskov , Jensen F. , Jensen P. Waage 
Published: May 2005

AbstractSurface‐enhanced Raman spectra of the two thiazole orange derivatives, TO6 {1‐(N,N'‐tetramethyl‐1,3‐propanediaminopropyl)‐4‐[3‐methyl‐2,3‐dihydro(benzo‐1,3‐thiazole)‐2‐methyliden] quinolinium triiodide} and TOTO {1,1′‐(4,4,8,8‐tetramethyl‐4,8‐diazaundecamethylene)‐bis‐ 4‐[3‐methyl‐2,3‐dihydro(benzo‐1,3‐thiazole)‐ 2‐methylidene] quinoliniumtetraiodide}, were recorded with visible (457.9 and 514.5 nm) and near‐infrared (1064 nm) excitation on silver colloids. The spectra were compared with the corresponding non‐enhanced Raman spectra obtained in the near‐infrared region and the resonance Raman spectra obtained with visible excitation. The qualitative enhancement pattern is explained within the electromagnetic theories. Partial assignment of the vibrational wavenumbers was achieved by comparison of observed band positions and intensities in the IR and Raman spectra with wavenumbers and intensities from quantum chemical calculations. Information on the adsorption geometry at the silver surface can be obtained on basis of this assignment. The surface‐enhanced Raman spectrum of TOTO on gold colloids was recorded with 1064 nm excitation and compared with the corresponding spectra on silver colloids.
Deconvolution of the Raman spectrum of amorphous carbon
Authors: Wang Qi , Allred D. D. , Knight L. V. 
Published: May 2005

AbstractA constrained non‐linear deconvolution method was used to analyse the Raman spectrum of amorphous carbon. The method was tested by applying it to a model spectrum. Before the deconvolution the observed Raman spectrum was smoothed by a least‐squares convoluting procedure. The proper width of the spread function used in the deconvolution was determined by examining the reversibility of the deconvolution process. The deconvolution result for the Raman spectrum of amorphous carbon has a form very similar to the phonon density of states of graphite. This is taken to be additional evidence for Shuker and Gamon's model for Raman spectra of amorphous materials. Potentially, the deconvolution method can also be used for other aspects of Raman spectrum analysis of amorphous materials, such as finding the relative intensity of each peak of study the structure of the material.
The effect of cytoplasmic proteins on the reaggregation of dissociated ghost membranes of Bacillus megaterium KM
Authors: Devor K. A. , Makula R. A. , Lennarz W. J. 
Published: May 2005

AbstractThe effect of cytoplasmic proteins on the reassociation of membrame proteins and lipids which have been solubilized in sodium dodecyl sulfate and urea has been investigated. The cytoplasmic proteins have been found to inhibit the reassociation of the membrane proteins. Moreover, approximately 15% of the cytoplasmic proteins co‐aggregate with the membrane components after removal of the sodium dodecyl sulfate and urea.
Selective solubilization of proteins and phospholipids from red blood cell membranes by nonionic detergents
Authors: Yu John , Fischman Donald A. , Steck Theodore L. 
Published: May 2005

AbstractTreatment of isolated human erythrocyte membranes with Triton X‐100 at ionic strength ⋍0.04 preferentially released all the glycerolipid and glycoprotein species. At low ionic strength, certain nonglycosylated polypeptides were also selectively solubilized. The liberated polypeptides were free of lipids, but some behaved as if associated into specific oligomeric complexes. Each detergent‐insoluble ghost residue appeared by electron microscopy to be a filamentous reticulum with adherent lipoid sheets and vesicles. The residues contained most of the membrane sphingolipids and the nonglycosylated proteins. The polypeptide elution profile obtained with nonionic detergents is therefore nearly reciprocal to that previously seen with a variety of agents which perturb proteins. These data afford further evidence that the externally‐oriented glycoproteins penetrate the membrane core where they are anchored hydrophobically, whereas the nonglycosylated polypeptides are, in general, bound by polar associations at the inner membrane surface. The filamentous meshwork of inner surface polypeptides may constitute a discrete, self‐associated continuum which provides rather than derives structural support from the membrance.
Purification and properties of the sodium–potassium transport adenosinetriphosphatase from the rectal gland of the spiny dogfish squalus acanthias
Authors: Hokin Lowell E. 
Published: May 2005

AbstractThe (Na + K)–activated adenosinetriphosphatase (NaK ATPase) has been purified from Lubrol extracts of membranes from the rectal glands of Squalus acanthias. The specific activity of the purified enzyme is 2 to 3 times that previously reported by others after correction of their specific activities for detergent activation. The yield of the enzyme from the membranes is 70%. The enzyme is highly stable both at 0° and in the frozen state. Ninety‐five percent of the enzyme consists of two subunits–the catalytic subunit with a MW of 97,000 and a glycoprotein with a MW of 55,000. At the last stage of purification the enzyme reverts to various membranous forms: the thickness of the membrane is about 80 Å; projections (probably the glycoprotein) of about 40 Å in diameter are seen at regular intervals.
The β‐glucoside system of Escherichia coli III. Properties of A P–HPr: β‐Glucoside phosphotransferase extracted from membranes with detergent
Authors: Rose Steven P. , Fox C. Fred 
Published: May 2005

AbstractA P‐HPr:β‐glucoside phosphotransferase (enzyme IIbgl)The nomenclautre of the enzymes II is that suggested by Lin (1)
has been extracted from membranes of a β‐glucoside fermenting strain of Escherichia coli K 12 using the nonionic detergent Triton X–100. The extracted enzyme was rendered virtually free of both lipid and detergent by chromatography on DEAE‐cellulose. At this stage, the partially purified enzyme had negligible activity, but activity was restored effectively by the addition of (1) nonionic detergents of the Tween or Triton series and (2) crude E. coli phospholipids or an anionic lipid enriched fraction, but not phosphatidylethanolamine. Detergent activators were most effective at or near the critical micelle concentration, but were inhibitory when added at concentrations above the critical micelle concentration.In order to obtain maximal initial rates of phosphotransferase activity, it was necessary to incubate the extracted, partially purified enzyme with detergent activator and HPr prior to the addition of the other assay system components. High detergent concentration inhibited the initial rate of phosphorylation by interfering with an essential step (or steps) that occur during this preliminary incubation. The activation occuring during the preliminary incubation was also highly temperature dependent; a precipitous decrease in activation was detected below 16° when Tween 40 was employed as the detergent activator.Phosphorylation mediated by the membrane associated form of the phosphotransferase was not influenced by the physical state of the lipid components of the membrane. This is in marked contrast to the properties of the phosphorylation reaction mediated by the phosphotransferase in intact cells.
Assembly and attachment of bacteriophage T4 tail fibers
Authors: Bishop R. J. , Conley M. P. , Wood W. B. 
Published: May 2005

AbstractBacteriophage T4 tail fibers are rodlike structures with a contour length of about 1400 Å, a diameter of about 45 Å, and a total mass of about 600,000 daltons. The assembly of the tail fibers and their subsequent attachment to the phage particle are under the control of 8 phage‐induced proteins. The gene control and molecular weight of each protein are known. The sequence of gene‐controlled steps has been determined by the characterization of intermediates that accumulate when various steps are blocked by mutation. The protein composition of the fibers and their precursors has been determined by purification and electrophoretic analysis.Four of the eight gene products are structural components of the tail fiber. These proteins are P34 (150,000 daltons, 2 copies), P37 (120,000 daltons, 2 copies), P35 (40,000 daltons, 1 copy), and P36 (24,000 daltons, 2 copies). The wac (whisker antigen control) gene product is a structural component of the phage whiskers. The remaining three gene products, P38, P57, and P63, are not structural components of the phage particle. Both P63 and the wac gene product promote the attachment of tail fibers to the phage particle. P63 has been shown to act catalytically. Both P38 and P57 are somehow involved in the folding of the major tail fiber structural proteins (P37 and P34). The normal requirement for P38 and P57 functions can be bypassed by secondary mutations.
P22 morphogenesis II: Mechanism of DNA encapsulation
Authors: Tye Bik‐Kwoon , Botstein David 
Published: May 2005

AbstractPhage P22 is known to have a linear duplex chromosome which is circularly permuted and terminally repeated. The propagation of these features of the mature phage DNA is accounted for by the fact that phage DNA lengths (headfuls) are cut from an intracellular intermediate form of phage DNA several phage genomes in length (concatemer) as first suggested by Streisinger. Studies with mutant phages show that cutting of concatemer DNA is intimately connected to the morphogenesis of the phage head.We have also found, by constructing a partial denaturation map of mature P22 DNA, that circular permutation in P22 DNA is restricted: all of the ends of the mature DNA fall within 20% of each other on the physical map. The limited distribution of ends can be explained by Streisinger's “headful” packaging model with the additional specifications that: a. the intracellular precursor DNA is no longer than ten times the length of mature phage DNA; b. encapsulation of DNA starts at a unique site; c. encapsulation proceeds sequentially therefrom.This model is supported by the distribution of molecular ends in denaturation maps of two deletion phage DNAs. We found, as expected from our model, that the extent of permutation is a direct function of the length of terminal repetition.
The role of ring aggregates and other structures in the assembly of microtubules
Authors: Weisenberg R. C. 
Published: May 2005

AbstractBeef brain tubulin isolated by cycles of polymerization and depolymerization contains two components, 6S subunit and a 25–35S boundary containing ring‐shaped aggregates of tubulin. The rings disappear during microtubule polymerization, and the incorporation of ring tubulin into microtubules has been investigated by studying the changes in the sedimentation of tubulin which occur during polymerization. The “30S” boundary was separated from the 6S boundary by sedimentation at low temperatures. The temperature was then raised by letting a small amount of air into the vacuum chamber and the changes in sedimentation rate and concentration of each component determined as the tubulin polymerized. The 30S material polymerizes preferentially as determined by its decrease in concentration at polymerizing temperatures. Simultaneously with its decrease in concentration the 30S also decreases in sedimentation rate. The decrease in concentration of the 30S correlates well with polymerization while the decrease in sedimentation rate can occur independently of polymerization. The results indicate that the rings are not transformed directly into microtubules, but break down into subunits or small aggregates and these then assemble into microtubules. The rings may serve as a “storage aggregate” of active subunits. The presence of a possible storage aggregate in a dividing cell, the eggs of the surf clam, Spisula solidissima, has been indicated by measurements of particulate tubulin changes during the cell cycle. Microtubule assembly in vitro in homogenates of these eggs indicates that the amount of tubulin which forms microtubules may be controlled by the functioning of the microtubule organizing center.
Assembly of lipids and proteins in escherichia coli membranes
Authors: George‐Nascimento C. , Zehner Zendra E. , Wakil Salih J. 
Published: May 2005

AbstractPresently there is much interest in the relationship between the structure and function of biological membranes. An approach to the understanding of this relationship has been the study of the effect of the modification of the membrane lipids on the function of membrane‐associated activities. In our laboratories we have modified the apolar portion of the membrane lipids of unsaturated fatty‐acid auxotrophs of Escherichia coli and investigated the effect of such modifications on enzymes of the electron‐transport system. From these studies we were able to conclude that E. coli regulates the relative fatty‐acid content of its phospholipids and maintains a certain membrane fluidity necessary for proper membrane function (1–3). We have also proposed that lipids are heterogeneously distributed within the membrane in domains of differing fluidity (4). The studies of McConnell, Chapman, and others (5–13) have corroborated these concepts and extended them to other biological and model membranes. In this paper we review some of our previous results and present evidence to show how NADH and D‐lactate oxidases of E. coli membranes are influenced by the fluid states of membrane phospholipids. Preliminary evidence is also presented to show that biogenesis of membranes probably occurs by independent insertion into the membranes of lipids and proteins which upon subsequent interaction with each other form the functional lipoprotein units.
On the molecular basis of action of cytochalasin B
Authors: Lin Shin , Spudich James A. 
Published: May 2005

AbstractTritium‐labeled cytochalasin B binds rapidly and reversibly to mammalian cells, and a class of high‐affinity sites (Kn ≅ 10−7 M) and a class of low‐affinity sites (KD ⩾ 10−5 M) are detected. In red blood cells, the high‐affinity binding sites (about 3 × 105 per cell) are associated with the plasma membrane, and at least 80% of these appear to be intimately related to the glucose transport system. Fractionation of cellular components of platelets by differential centrifugation and gel filtration chromatography reveals that the high‐affinity binding sites in these cells are also associated with membranous materials. A substantial number of the low‐affinity binding sites can be traced to platelet actin. The binding of cytochalasin B to actin is consistent with the alteration of intrinsic viscosity and morphology of actin filaments in vitro by the compound at concentrations of around 10−5‐10−4 M. The interaction of cytochalasin B with actin may account for its inhibitory effect on various forms of cell motility.
Light energy conversion in halobacterium halobium
Authors: Stoeckenius Walther , Lozier Richard H. 
Published: May 2005

AbstractHalobacterium halobium carries out photophosphorylation. A rhodopsin‐like protein, bacteriorhodopsin, located in the cell membrane mediates the first step in energy transduction, the conversion of light energy into a chemiosmotic gradient. After absorption of a photon, bacteriorhodopsin undergoes a series of fast reactions, returning to its original state in a few milliseconds. In continuous light it cycles continuously at 100 to 200 cps. During a cycle protons are taken up on the cytoplasmic side of the membrane and released on the outer surface, thus generating a chemiosmotic gradient which can drive phosphorylation of ADP to ATP.
On the physiological functions of teichoic acids
Authors: Tomasz Alexander , Westphal Monika , Briles Eve B. , Fletcher Paul 
Published: May 2005

AbstractThe 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 develop pleiomorphic alterations in several physiological properties, which include resistance to detergent‐induced lysis and inhibition of cell separation (chain formation). We report here the results of physiological studies on the mechanism of these two phenomena. Our results are summarized in the following: (a) Pneumococci grown on various amino alcohols produce cell walls of identical amino sugar and amino acid composition. (b) Both choline‐ and EA‐containing teichoic acids seem to follow the same conservative pattern of segregation during growth and cell division. (c) Lysis sensitivity of pneumococci requires the juxtaposition of lysissensitive (choline‐containing) cell walls and endogenous autolysin at the cell wall growth zone. (d) Upon readdition of choline to ethanolamine‐containing cells, lysis sensitivity and catalytically active (C‐type) autolysin reappear in the bacteria with the same kinetics. (e) The chains of EA‐grown pneumococci contain fully compartmentalized cells and normal cross walls.
Hemocyanin–antibody labeling of rhodopsin in mouse retina for a scanning electron microscope study
Authors: Jan Lily Yeh , Revel Jean‐Paul 
Published: May 2005

AbstractTo 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 hemocynin‐labeled goat antibodies specific against rabbit antibody. The distribution of hemocyanin label on mouse retina and the technique used for labeling are discussed.
An activation mechanism for ATP cleavage in muscle
Authors: Harrington William F. , Reisler Emil , Burke Morris 
Published: May 2005

AbstractEvidence 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 actin in the vicinity of one of the essential sulfhydryl groups, Thus opening the stable ring leading to rapid dissociation of split products. This idea is consistent with the kinetic scheme of ATP cleavage developed recently by other workers and allows a prediction of the shift in population of intermediate states with changes in solvent conditions. It is also supported by our recent studies on the spatial geometry of the ring. The possibility that other nucleophilic groups may replace the sulfhydryl groups in other contractile systems is considered. The relevance of the ring structure to the tension generating event is discussed on the basis of recent measurements of the rate of contraction of modified (SH1‐blocked) actomyosin threads. Results indicate that the ability to form the ring structure is an essential requirement of the contractile process in these systems, and, moreover, that single, modified heads of myosin can act independently to produce the same rate of contraction as native myosin. This latter finding suggests that the myosin duplex exhibits some type of negative cooperativity in the contractile process.
Segmental flexibility in the myosin molecule: Evidence from binding studies of myosin fragments with actin
Authors: Peller Leonard 
Published: May 2005

AbstractFrom 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 determinable parameter, the local concentration of a second segment after the first of a pair is attached to the lattice. From combined data for these two association reactions a value of 10−4 M is obtained for this quantity. The large degree of segmental flexibility reported for the free heavy meromyosin is still manifested in the association with actin.