bluuebunny/crossref_metadata_2025_split huggingface dataset:
Fourier transform surface‐enhanced Raman scattering for the detection and identification of polyaromatic hydrocarbons
Authors: Stewart S. D. , Fredericks P. M. 
Published: May 2005

AbstractFourier transform surface‐enhanced Raman (FT‐SER) spectra of 18 polyaromatic hydrocarbons (PAHs) were measured on a silver surface which had been previously roughened by an oxidation‐reduction procedure in an electrochemical cell. The sample was placed on the clean surface as a solution in an organic solvent and the solvent allowed to evaporate. All the samples had significantly different SER spectra. Detection limits were around 10−9 mol for most compounds but were higher for a few compounds, particularly azulene. For most samples the SER spectrum obtained was similar to the FT‐Raman spectrum of the solid sample. For one sample, azulene, a different spectrum was obtained by the SER technique, indicating a different, or additional, SER mechanism for this sample. A brief investigation of the quantitative aspects of the technique showed that, over the range studied, the intensity of the SER spectrum was related linearly to the amount of compound present on the surface.
Interactions in liquid mixtures of formamide isotopomers studied by Raman spectroscopy
Authors: Mortensen A. , Nielsen O. Faurskov , Yarwood J. , Shelley V. 
Published: May 2005

AbstractRecently, anomalies concerning both intensities and peak positions of Raman bands in the carbonyl stretching region of liquid mixtures of different isotopomers of formamide were reported. More detailed investigations have now been performed for liquid mixtures of HCONH2 and H13CONH2, and Raman spectra of mixtures of DCONH2 and DCOND2 in the carbonyl stretching region are presented. In the system DCONH2‐DCOND2, collapse of the isotropic carbonyl bands was observed in the mixtures as previously reported for HCONH2‐HCOND2 and HCOND2‐DCOND2. The system HCONH2—H13CONH2 shows anomalous intensities compared with those expected for simple binary mixtures. However, this system does not show collapsing carbonyl bands in the isotopomeric mixtures. The phenomenon of collapsing bands can be explained in terms of a model known as mutual entrainment.
Non‐destructive ‘in situ’ Raman study of artistic glasses
Authors: Bertoluzza A. , Cacciari S. , Cristini G. , Fagnano C. , Tinit A. 
Published: May 2005

AbstractA non‐destructive ‘in situ’ Raman spectroscopic study was carried out on 28 artistic glasses grouped in eight age classes between 1750 and 1940, in order to characterize the authenticity (age) of these objects. Other non‐‘in situ’ instrumental methods which require only micro amounts of sample, should be avoided in this case owing to the great brittleness of the samples. Although it was not found possible to characterize the age of the samples from the Raman spectra, which were very similar for all the different glasses examined, nevertheless, the intensity of the fluorescence band increased with the age of the samples. The logarithm of the ratio between the 1080 cm−1 Raman band intensity and that of the fluorescence band, obtained from the spectra where the fluorescence band was kept at the same intensity for the different samples, shows a linear relationship with the age of the glasses, and therefore constitutes a spectroscopic marker for the characterization of the authenticity of the samples.
Raman and infrared spectra, conformational stability, vibrational assignment and ab initio calculations for ethyl chloroformate
Authors: Bohets H. , van der Veken B. J. 
Published: May 2005

AbstractInfrared (4000‐50 cm−1) spectra of gaseous, amorphous and crystalline solid ethyl chloroformate, ClCOOCH2CH3, and mid‐infrared spectra (4000‐500 cm−1) of the chloroformate dissolved in liquefied krypton were recorded. Raman spectra of the liquid and solid phases were investigated from 4000 to 50 cm−1. MP2 and RHF ab initio calculations were carried out using a 6—31G* basis set. The calculations show that the compound can occur as the s‐cis,trans, the s‐cis,gauche, the s‐trans,trans and the s‐trans,gauche conformers. For each conformer the optimized structural parameters, the vibrational wavenumbers, infrared intensities, Raman scattering activities and potential energy distributions were calculated. Both s‐cis conformers were identified in the vibrational spectra of all non‐crystalline phases. Evidence for the presence of the s‐trans conformers is found in the liquid‐phase Raman spectra. The enthalpy difference between the s‐cis,gauche and s‐cis,trans conformers was determined in the pure liquid phase to be 3.2 ± 0.3 kJ mol−1. Also in the liquid phase, the enthalpy difference between the observed s‐trans and the s‐cis,trans conformers was determined to be 14.3 ± 0.8 kJ mol−1. Vibrational spectra of the crystalline solid, which contains only the s‐cis,trans conformer, showed that ethyl chloroformate can crystallize in two different forms. A complete assignment of the infrared and Raman spectra is proposed.
Infrared and Raman spectra of L‐asparagine and L‐asparagine‐d5 in the solid state
Authors: Casado J. , LÓPez Navarrete J. T. , Ramírez F. J. 
Published: May 2005

AbstractThe infrared and Raman spectra of L‐asparagine and ND3+, ND2‐L‐asparagine as solid samples were recorded. The data obtained were used to propose a general assignment of the fundamental vibrational modes on the basis of the measured isotopic shifts and correlations with previous data reported for other amino acids and related molecules.
Influence of Pt—Cl force constants on the Raman lineshapes in Pt35Cl/37Cl chains
Authors: Bardeau J. F. , Bulou A. , Swanson B. I. 
Published: May 2005

AbstractThe influence of the 35 Cl/37 Cl isotopic disorder of natural chlorine on the Raman and infrared lineshapes of the vibrational modes in PtCl chains was calculated as a function of the interionic force constants in a one‐dimensional model. It is shown that the fine structure of the Raman line is strongly dependent of the Pt3+σ‐Cl and Pt3‐σ‐Cl force constants, and so it can be used to estimate the charge disproportion σ. From the case of [Pt(en)2][Pt(en)2Cl2](ClO4)4 it appears that the description of the high‐wavenumber infrared line (v2) requires one to take into account interactions with more distantations. It is also shown that the intensity of the lowwavenumber infrared‐active mode (v3) is so weak that the corresponding line may have never been observed.
Polysaccharide vibrational Raman optical activity: Laminarin and pullulan
Authors: Bell Alasdair F. , Hecht Lutz , Barren Laurence D. 
Published: May 2005

AbstractThe backscattered Raman optical activity (ROA) spectra of the β(1‐3)‐linked polysaccharide laminarin, and its dimer repeating unit D‐laminarihiose, together with those of the predominantly α(l‐4)‐linked polysaccharide pullulan, and its trimer repeating unit D‐maltotriose, between 350 and 1500 cm−1 in aqueous solution are reported and discussed. Several differences are evident between the ROA spectra of laminarin and D‐laminaribiose which are ascribed to triple helix formation in the polysaccharide. In particular, the signs of four ROA signals between ca. 1050 and 1150 cm−1 are reversed and two ROA signals assigned to vibrations involving the glycosidic link observed at ca. 445 and 1431 cm−1 change sign and increase in intensity, respectively. In contrast, pullulan, which adopts a random coil‐type structure in aqueous solution, generates an ROA spectrum that closely resembles that of D‐maltotriose.
Structure of the lipid phase of rauscher murine leukemia virus
Authors: Landsberger Frank R. , Lenard John , Compans Richard W. , Paxton John 
Published: May 2005

AbstractThe lipid‐containing membrane of Rauscher murine leukemia virus was studied using stearic acid spin labels with the nitroxide ring on the C5 and C16 positions. The environment of the C5 spin label was found to be much more rigid than that of the C16 spin label. This result, which parallels similar observations in red cell membranes and influenza virus, suggests that the lipid phase of Rauscher murine leukemia virus is arranged in a bilayer.
Four gel systems for electrophoretic fractionation of membrane proteins using ionic detergents
Authors: Fairbanks Grant , Avruch Joseph 
Published: May 2005

AbstractMembrane proteins were fractionated electrophoretically in polyacrylamide gels containing either anionic or cationic detergent at either pH 2.4 or 8.3. In all four systems, polypeptides migrated as monomers bearing the charge of the detergent ion and semi‐logarithmic molecular weight–mobility relationships pertained. Electrophoresis of erythrocyte membrane proteins in these systems yielded very similar protein staining patterns but revealed significant differences in sialoglycoprotein migration.
Cis‐ and trans‐ membrane control of cell surface topography
Authors: Nicolson Garth L. 
Published: May 2005

AbstractThe topographic distributions of cell surface components can be modified by perturbations from the cell membrane exterior (cis‐membrane effect) or by perturbations from the cell interior that are transferred across the membrane (trans‐membrane effect). Using the human erythrocyte ghost as a model system, cis‐membrane effects on the topography of anionic sites were produced in B+ ghosts with anti‐B sera (but not with anti‐A), R. communis agglutinin and concanavalin A (but not with D. biflorus agglutinin). Cis‐membrane linkage was monitored by the state of aggregation of membrane‐bound colloidal iron hydroxide particles which bind almost exclusively to neuraminidase‐sensitive N‐acetylneuraminic acid residues on the outer surface. Trans‐membrane effects were observed when purified antibodies against an inner surface membrane protein, spectrin, were sequestered inside the ghosts. The sequestered antispectrin bound to spectrin at inner membrane surface and caused aggregation of the anionic sites on the outer membrane surface. The trans‐membrane effects of antispectrin required intact γG antibodies (Fab would not substitute) and was time‐ and concentration‐dependent.
Correlations between fatty acid distribution in phospholipids and the temperature dependence of membrane physical state
Authors: Linden C. D. , Keith A. D. , Fox C. F. 
Published: May 2005

AbstractCytoplasmic membranes of an unsaturated fatty acid auxotroph of Escherichia coli have been studied using spin labeled hydrocarbon probes. These studies reveal that the membrane lipids undergo changes of state at critical temperatures which reflect the physical properties of the fatty acid supplement supplied to the cells during growth. The critical temperatures observed in spin labeled membranes correlate with characteristic temperatures in membrane functions. Lipid analysis reveals that fatty acid composition and distribution in membrane phospholipids are primary determinants of the temperatures at which changes of state are observed in membrane lipids. Fatty acid composition and distribution can also produce unique interactions between certain spin label probes and their lipid environment.
A comparison of characteristic temperatures for transport in two unsaturated fatty acid auxotrophs of escherichia coli
Authors: Linden Carol D. , Fox C. Fred 
Published: May 2005

AbstractThe rate of sugar transport as a function of temperature has been compared in two unsaturated fatty acid auxotrophs. One of these, the parent strain 30E, can β‐oxidize the unsaturated fatty acid supplements, whereas the β‐oxidation defective progeny strain 30Eβox− cannot. In a previous study, Arrhenius plots for transport of β‐glucosides and β‐galactosides by strain 30Eβox− revealed striking departures from linearity at both a lower and an upper characteristic temperatures. By electron spin resonance (esr) these temperatures were shown to correlate with the temperatures where the membrane lipids undergo a transition from a totally solid state to a solid–liquid equilibrium and from a solid–liquid equilibrium to a totally liquid state, respectively (1). In the present study with strain 30E we have made the following observations:

Arrhenius plots for transport rate are usually more complex, often revealing three characteristic temperatures. Two of these correlate with the upper and lower characteristic temperatures observed in strain 30Eβox−. The third characteristic temperature falls between the previously described upper and lower ones.
In cells supplemented during growth with elaidate, the third characteristic temperature was identical within experimental limits for both β‐glucoside and β‐galactoside transport. indicating that it is likely to arise from some interaction in the bulk lipid phase. This conclusion is supported by the fact that the boundary of a change in physical state is also observed at this temperature by electron spin resonance.
In cells supplemented during growth with oleate, two or three characteristic temperatures were observed depending upon the transport system studied. Although glucoside and galactoside transport had the same lower characteristic temperature, these systems had no common upper characteristic temperature.
In cells supplemented during growth with the lipid density label, bromostearic acid, three characteristic temperatures were observed for β‐glucoside transport in both strains 30E and 30Eβox−.
Membrane assembly in escherichia coli V. Subcellular localization of phospholipid biosynthesis
Authors: Machtiger Neal A. , Fox C. Fred 
Published: May 2005

AbstractThe subcellular distribution of enzymes involved in lipid biosynthesis in E. coli K12 has been studied following various modes of cell disruption and fractionation of the subcellular components. Though most biosynthetic enzymes were found associated with the cytoplasmic membrane fraction regardless of the procédures of disruption or fractionation employed, the enzymes responsible for the synthesis of the major lipid of E. coli (phosphatidylethanolamine) and of its precursor (phosphatidylserine) had no distinct localization in extracts. These findings are discussed in the context of current models for the assembly of bacterial membranes.
Self‐assembly of collagen
Authors: Fessler John H. 
Published: May 2005

AbstractThe structure and self‐assembly of collagen and procollagen molecules are reviewed. The registration peptides of procollagen have specific recognition properties which assure (1) selection of component polypeptide chains and (2) registration of their N‐termini, facilitating orderly folding into a collagen helix. The stability of this helix relative to body temperature is critically altered by post‐ribosomal hydroxylation of proline residues. The registration peptides of procollagen may have additional functions such as preventing intracellular fiber formation.
Renaturation of disulfide‐linked procollagen
Authors: Fessler Liselotte I. , Rudd Colette , Fessler John H. 
Published: May 2005

AbstractDisulfide‐linked, triple‐stranded procollagen (pro γ 112) was isolated from chick embryo skull bones. It was reversibly denatured and renatured as judged by sedimentation properties and susceptibility to digestion with pepsin. Refolding was an intramolecular process and aggregation between molecules did not occur.
Some symmetry considerations for the fibrinogen‐fibrin assembly system
Authors: Doolittle Russell F. 
Published: May 2005

AbstractThe formation of fibrin gels involves many operations which are fundamental to other assembly schemes, including limited proteolysis, spontaneous associations, and covalent stabilization. Despite a quarter century of intensive effort by a large number of laboratories, the orientation of the fundamental units in the gel is not known, nor, for that matter, is the arrangement of the subunit chains within the parent fibrinogen molecule. In this article some symmetry considerations are discussed in light of the geometry of the starting molecules and conditions necessitated by the covalent stitching which occurs after gel formation. Only a dimeric molecule in which the twofold symmetry axis coincides with a minor axis of an elongated fibrinogen molecule satisfies all the conditions.
P22 morphogenesis I: Catalytic scaffolding protein in capsid assembly
Authors: Casjens Sherwood , King Jonathan 
Published: May 2005

AbstractAbout 250 molecules of the 42,000 molecular weight gene 8 product catalyze the polymerization of the major phage coat protein into a precursor shell temporarily containing both proteins. The resulting prohead appears to be a shell structure with the P8, or scaffolding protein, on the inside, and the coat protein on the outside. In concert with DNA condensation inside the shell, all 250 scaffolding molecules exit from the prohead, without proteolytic cleavage. These molecules then recycle and catalyze the formation of more proheads from newly synthesized coat protein. Such proteins, which catalyze assembly by temporarily associating with an intermediate stage, may represent a general mechanism of macromolecular assembly.
Phage head size determination and head protein cleavage in vitro
Authors: Pruss Gail , Barrett Kathleen , Lengyel Judith , Goldstein Richard , Calendar Richard 
Published: May 2005

AbstractSatellite phage P4 causes the head proteins of a helper phage, such as P2, to form a small head. This small head is never found in cells infected by the helper virus alone. This finding, coupled with the dominance of P4 over its helper, indicates that the P4 genome has the potential for specific head size determination. Satellite phage P4 codes for a late protein which is found in the P4 head (45 copies/head). This protein may determine head size. Our finding that the small size of P4 DNA does not determine small head size in an in vitro DNA packaging system lends further support to the idea that a P4 protein determines small head size.Formation of P2 headlike structures is accompanied by cleavage of P2 head proteins. Cleavage of the major head protein precursor can be observed in vitro after lysis of infected cells with lysozyme. The rate of this in vitro reaction is not affected by deoxyribonuclease; thus there cannot be a tight coupling between DNA packaging and the cleavage of the major capsid protein.
Binding properties of the plant photoreceptor phytochrome to membranes
Authors: Marmé Dieter 
Published: May 2005

AbstractPhytochrome (P), a chromoprotein of 120,000 MW, occurs at low concentrations in all higher plants. The chromophore is an open tetrapyrrole. The pigment exists in two light‐absorbing forms: Pr, which absorbs at 660 nm, and Pfr, which absorbs at 730 nm. These forms are interconvertible by light. Pr, the physiologically inactive form, exists in dark‐grown plants; Pfr, the active form, appears after irradiation with red light, P‐mediated responses, of which about 80 are known, range from short‐time effects (sec) such as bioelectric potentials, to long‐time effects (hr) such as increases in enzymatic activity. Measurements of phototransformation in vivo with polarized light suggest that P is localized in the plasma membrane. Particulate cell fractions contain about 70% of total extractable P if Pfr is present and only 4% if Pr is present. Evidence indicates that the fraction containing Pfr may be the plasma membrane. One can isolate a partially solubilized membrane system, which can be reversibly reconstituted by adding Mg. The reformed vesicles bind Pfr in vitro. Pfr binding increases with decreasing pH and decreases with increasing monovalent cation concentration. Pfr is released from the membrane by far red light (Pr is formed) and by Triton X‐100. We suggest that Pfr binding to a membrane induces conformational changes; the functional properties of this membrane are altered, which might lead to the observed phytochrome‐mediated responses.
Oxidation of lipids and membranes I: In vitro formation of peroxidative lipid polymers
Authors: Wolman Moshe 
Published: May 2005

AbstractFluorescent 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.The presence of egg albumen in the emulsion enhanced polymer formation with all oxidants. When the oxidants used are arranged in the order of decreasing speed of polymer formation, the order is different in the presence of albumen from what it is in the absence of albumen.With different oxidation catalysts most antioxidants and amino acids tested enhanced polymerization. In oxidation with ferric ions, with K‐dichromate, and without added oxidants the only antioxidants which delayed polymerization were “inhibitors”. “Retarders” enhanced polymerization. With KMnO4 slight delay was caused by some retarders.The findings indicate that not only oxidation catalysts, but also proteins, amino acids, and antioxidants enhance polymerization. The possibility is suggested that in animal cells lipid pigment formation might represent a mechanism for neutralizing free radicals.
Effect of crosslinking on mitochondrial structure and function
Authors: Tinberg Harold M. , Lee Calvin , Packer Lester 
Published: May 2005

AbstractRat liver mitochondria were treated with ethylacetimidateAbbreviations: SDS, sodium dodecylsulfate; DMS, dimethylsuberimidate; EA, ethylacetimidate; MBI, methylbutyrimidate; TMPD, N, N′, N′‐tetramethyl‐p‐phenylenediamine.
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 deionized water. Sodium dodecylsulfate‐polyacrylamide gel electrophoresis revealed that at concentrations > 5 mM dimethylsuberimidate nearly all mitochondrial polypeptides failed to enter 6% gels, indicating crosslinking of both membrane and soluble proteins. Extensive amidination by ethylacetimidate and methylbutyrimidate had little effect on ascorbate‐tetramethylphenylenediamine oxidase while extensive inhibition resulted from dimethylsuberimidate treatment. The possible involvement of molecular motion in electron transport is discussed.
The possible role of tightly bound adenine nucleotides in oxidative and photosynthetic phosphorylation
Authors: Rosing J. , Harris D. A. , Slater E. C. , Kemp A. 
Published: May 2005

AbstractThe tightly bound nucleotides of the beef‐heart mitochondrial ATPase are released during cold inactivation followed by ammonium sulfate precipitation. During incubation at 0°C the sedimentation coefficient (s20 W) of the ATPase first declines from 12.1 S to 9 S. Prolonged incubation or precipitation with ammonium sulfate leads to dissociation of the 9 S component into subunits with s20 W of 3.5 S. The 9 S component still bears bound nucleotides which exchange more extensively and rapidly with added nucleotides than those bound to the active 12.1 S component. The bound nucleotides are lost when the 9 S form dissociates into the smaller subunits. Thus, firm binding of nucleotides is a property of the quarternary structure of the enzyme.The exchangeability of the nucleotides bound to the ATPase of chloroplast membranes is greatly increased in membranes illuminated in the presence of pyocyanine. Pi can exchange into both the β and γ positions of the bound nucleotides when the membranes are energized in the presence of Mg2+. The exchange of the nucleotides and the incorporation of Pi are insensitive to the inhibitor Dio‐9 but are inhibited by the uncoupler S13.Abbreviation: S13, 5‐chloro‐3‐t‐butyl‐2′‐chloro‐4′nitrosalicylanilide.
This inhibition by S13 parallels that of the inhibition of photosynthetic phosphorylation. These findings are discussed with regard to our hypothesis that electron transfer causes release of preformed tightly bound ATP from the ATPase by inducing a conformational change.