bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigation of haem—protein coupling and structural heterogenity in myoglobin and haemoglobin by resonance Raman spectroscopy
Authors: Schweitzer‐Stenner Reinhard , Dreybrodt Wolfgang 
Published: May 2005

AbstractTo probe distortions of the haem group in myoglobin and haemoglobin resulting from ligand—haem and protein—haem interactions, the dispersion of the depolarization ratio and the resonance excitation profiles of the Raman line ν4 were analysed in terms of parameters describing intra‐ and intermanifold vibronic coupling between the Q and B states of the porphyrin macrocycle. These parameters depend linearly on symmetry classified normal distortions of the haem group. It is shown by group theoretical arguments that perturbations at the pyrrole nitrogens N(I) and N(III) of the haem cause B1g‐type distortions which increase with increasing tilt and bend angles of the proximal imidazole and the distal O2 ligand, respectively. Moreover, antisymmetric A2g‐type distortions are imposed via perturbations at the Cα atoms of pyrrole I and III when one of the ligands moves away from a position in which it eclipses the N(I)Fe2+N(III) line of the porphyrin. It is found that the influence of the proximal and distal ligand on the haem symmetry is different in myoglobin and haemoglobin. In oxymyoglobin the O2—haem interaction is responsible for the comparatively large B1g distortion at N(III). B1g distortions in oxyhaemoglobin and its isolated subunits are smaller then in oxymyoglobin. They are mainly caused by repulsive interactions between haem and proximal imidazole. A2g distortions at Cα(I) and Cα(III) are negligible in oxymyoglobin and small in deoxymyoglobin and deoxyhaemoglobin. They are comparatively strong, however, in oxyhaemoglobin and its isolated subunits, owing to the proximity and the large azimuthal angle of the proximal imidazole. In the isolated β‐chains of oxyhaemoglobin haem—protein coupling is more effective and causes larger B1g and A2g distortions than in the α‐chains. While the haem distortions investigated are independent of pH in the isolated α‐chain, they depend significantly on pH in the isolated β‐chain. This is caused by protonation of three titrable groups with pK = 5.8, 6.6 and 7.8, which were earlier assigned to His Eβ, His HC3β and His FG4β, respectively. In intact oxyHbA the allosteric coupling between these titrable groups and haem are modified by strengthening that of His HC3β and reducing that of His FG4β. Coupling between the former group and the haem is probably caused by the hydrogen bond between the penultimate Tyr HC2β and Val FG5β and steric interactions between Tyr HC2β and Cys F9β. Consequently, it is completely absent in the modified oxyhaemoglobin bis(maleimidomethyl) ether, in which the hydrogen bond between the penultimate Tyr HC2β and Val FG5β is ruptured.
Antibody—antigen interactions studied by means of Raman spectroscopy
Authors: Fagnano C. , Fini G. 
Published: May 2005

AbstractThe percentages of secondary structure of rabbit IgG and anti‐IgG in the lyophilized solid and aqueous solution state were obtained from the Raman spectra. The Raman spectrum of the lyophilized IgG—anti‐IgG complex was also recorded. The vibrational results indicate that the percentages of secondary structure of IgG do not change when lyophilized IgG is dissolved in water. Moreover, the secondary structure of IgG and of anti‐IgG changes only very slightly as a consequence of the complex formation. However, the Raman spectra in the SS stretching region suggest that some changes in the molecular geometry around the SS bridges take place as a consequence of the IgG—anti‐IgG complex formation.
Basic experiments in thin‐layer chromatography–fourier transform Raman spectrometry
Authors: Rau Axel 
Published: May 2005

AbstractIn some basic experiments, the feasibility is demonstrated of obtaining artifact‐ and fluorescence‐free spectra by in situ (Fourier transform (FT)) Raman spectrometry of TLC spots. In addition, the high sensitivity enhancement by using TLC–FT‐SERS of silver colloid‐activated chromatographic spots is shown.
Resonance Raman and time‐resolved resonance Raman studies of 3MLCT‐state populations in the series of ruthenium(II) complexes with bipyridine and tetramethylbipyridine
Authors: Danzer Gerald D. , Bajdor Krzystof , Kincaid James R. 
Published: May 2005

AbstractThe resonance Raman (RR) and time‐resolved resonance Raman (TR3) spectra of the complexes of ruthenium(II) with the ligands 2,2′‐bipyridine (bpy) and 4,4′,5,5′‐tetramethyl‐2,2′‐bipyridine (tmb) are reported. The RR spectra of the ground‐state species show no anomalous behaivor and are consistent with vibrationally isolated chelate ligands. The TR3 spectra provide definitive evidence that the 3MLCT excited‐state electron density is localized on the bpy ligand in the three complexes containing this ligand.
Investigation of the adsorption of 2‐phenyl‐1‐ethanethiol on silver by Raman spectroscopy
Authors: Mi Lee Hwa , Kim Kwan , Kim Myung Soo 
Published: May 2005

AbstractSurface‐enhanced Raman scattering (SERS) of 2‐phenyl‐1‐ethanethiol was investigated in a silver sol. The molecule was found to be chemisorbed dissociatively on the silver surface by rupture of its SH bond. Although both the trans and gauche conformers around the C‐1C‐2 axis could exist on the surface with submonolayer coverage, the trans conformer seemed to be dominant as the bulk concentration of the molecule was sufficient for full monolayer coverage. In the submonolayer coverage limit, a gradual trans‐to‐gauche transition was found to occur on the surface with increase in borohydride concentration in the sol solution. The vibrational assignment of the molecule in the liquid phase was also refined by using the SERS data.
Surface‐enhanced Raman scattering of pyridine in silver colloids excited in the near‐infrared region
Authors: Liang E. J. , Engert C. , Kiefer W. 
Published: May 2005

AbstractA scanning Raman spectrometer and an Nd: YAG laser operating at 1.06 μm were used to observe the surfaceenhanced Raman scattering (SERS) of pyridine in yellow silver colloids. Enhancement factors for the triangle ring breathing vibration mode at 1006 cm−1 and for the totally symmetric breathing mode at 1036 cm−1 are about 16.5 and 21 times larger, respectively, than those found for excitation at 514.5 nm. The large enhancement factors for excitation in the near‐infrared region suggest that further refinement of the theories currently proposed to explain the SERS effect is necessary.
Raman and infrared spectra, conformational stability, barriers to internal rotation, ab initio calculations and vibrational assignment of cyanomethyl methyl ether
Authors: Durig J. R. , Tang Qun , Phan H. V. 
Published: May 2005

AbstractThe Raman spectra (3400–10 cm−1) of gaseous, liquid and solid and the infrared spectra (3500–35 cm−1) of gaseous and solid cyanomethyl methyl ether (methoxyacetonitrile), (CN)CH2OCH3, were recorded. The farinfrared spectrum of the gas was recorded at a resolution of 0.10 cm−1 in the region from 370 to 30 cm−1. The fundamental asymmetric torsions of the gauche and trans conformations were observed at 112.5 and 104.6 cm−1, respectively, with the gauche form having two excited‐state transitions falling to lower wavenumber. From these data, along with the enthalpy difference and gauche dihedral angle, the asymmetric torsional potential function was calculated with the following coefficients: V1 = 153 ± 9, V2 = −619 ± 8, V3 = 1000 ± 2 and V4 = −100 ± 2 cm−1. From this potential function, the trans to gauche, gauche to gauche and gauche to trans barriers were determined as 512, 1592 and 951 cm−1, respectively, with an enthalpy difference of 439 ± 19 cm−1 (1255 ± 54 cal mol−1) and the gauche conformer the more stable form in the gas phase. The enthalpy difference was also determined experimentally from variable‐temperature studies of the Raman spectrum and a value of 337 ± 44 cm−1 (964 ± 126 cal mol−1) was obtained for the liquid with the gauche form more stable. Additionally, the symmetric methyl torsions of both gauche and trans forms were observed at 170.4 and 217.6 cm−1, respectively. On the basis of a one‐dimensional model, the barrier to internal rotation of the methyl moiety was determined as 839 cm−1 (2.40 kcal mol−1) for the guache conformer and 947 cm−1 (2.71 kcal mol−1) for the trans form. A complete vibrational assignment is proposed for a gauche‐trans equilibrium in the gas and liquid phases from the Raman (3200–10 cm−1) and infrared (3200–35 cm−1) spectra, but in the solid state only the gauche conformer remains. The structural parameters, conformational stability, barriers to internal rotation and fundamental vibrational frequencies which were determined experimentally were compared with those obtained from ab initio calculations employing the RHF/4–31G*, RHF/6–31G* and MP2/6–31 + + G** basis sets. These results were compared with the corresponding quantities obtained for some similar molecules.
Polarized Raman spectra and factor group analysis of methylammoniummercury trichloride crystals
Authors: Hossain M. Abul , Sattar Abdus , Srivastava J. P. , Bist H. D. 
Published: May 2005

AbstractPolarized Raman spectra of methylammoniummercury trichloride crystals were measured at room temperature. Factor group analysis involving the correlation method was applied. The observed spectra were interpreted in terms of internal and external oscillations of the constituent molecular ions, CH3NH3+ and HgCl3−.
Raman and infrared spectra, conformational stability, barriers to internal rotation and ab initio calculations of fluorocarbonyl isocyanate
Authors: Durig J. R. , Guirgis G. A. , Krutules K. A. , Phan H. , Stidham H. D. 
Published: May 2005

AbstractThe Raman (3100–10 cm−1) and infrared (3100–30 cm−1) spectra of fluorocarbonyl isocyanate, FC(O)NCO, were recorded for the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. The observed bands are assigned on the basis of the more stable cis conformer (isocyanate group cis to the carbonyl bond) in the fluid states but only the trans conformer remains in the annealed solid. From temperature dependence studies of the Raman spectra of the gas and liquid, two pairs of conformer peaks were used to determine Δ H values of 258 ± 47 cm−1 (738 ± 134 cal mol−l) and 140 ± 29 cm−1 (400 ± 83 cat mol−1), respectively, with the cis conformer the more stable rotamer in both phases. Additionally, variable‐temperature studies of the infrared spectrum of the sample dissolved in liquified Kr gave ΔH = 150 ± 28 cm−1 (429 ± 80 cal mol−1), which should closely represent the ΔH value for the gas. A complete vibrational assignment is proposed for both conformers based on infrared bard contours, Raman depolarization data, group frequencies, relative intensities and normal coordinate calculations. The experimental conformational stability, barriers to internal rotation, structural parameters and fundamental vibrational wavenumbers were compared with those obtained from ab initio gradient calculations employing the RHF/3–21G, RHF/6‐31G* and /or MP2/6‐31G* basis sets and to the corresponding quantities obtained for some similar molecules.
Non‐linear Raman spectroscopy of liquid crystals: Polarization measurements and relaxation processes in 4‐cyano‐4′‐heptylbiphenyl (7CB)
Authors: Davies A. N. , Jeremy Jones W. , Price Alun H. 
Published: May 2005

AbstractThe non‐linear Raman spectrum of 4‐cyano‐4′‐heptylbiphenyl is reported. Measurements of depolarization ratios of the vibrational bands at 2224 cm−1 (CN stretching), 1606 cm−1 (aromatic ring stretching) and 1185 cm−1 (CH aromatic in‐plane deformation) are used to evaluate the order parameters (〈P2〉 and 〈P4〉) using a ‘line model’ for the molecules. The results are internally consistent and also show the same general features (including some discrepancies in 〈P4〉) reported by other workers. Nevertheless, the results demonstrate that the technique is capable of wide application to the study of the anisotropic properties of liquid crystals and provides a valuable probe into the study of the biaxial nature of these sytems.
Picosecond time–resolved Raman spectroscopy of S1p‐terphenyl and p‐terphenyl d14 in solution: Time‐dependent changes of Raman band shapes
Authors: Iwata Koichi , Hamaguchi Hiro‐o 
Published: May 2005

AbstractThe picosecond time‐resolved Raman spectra of p‐erphenyl and its deuterated analogue (dl4) in the first excited singlet (S1) electronic state were observed in heptane and acetonirile solutions. The most intense band in the S1, p‐erphenyl at 750 cm−1 is assigned to an in‐plane ring vibration based on the shift on the deuteration. The peak position and the bandwidth of the 750 cm−1 band change as the time delay between the pump and probe pulses changes. The initial changes in the position and width appear between 0 and 5 ps, which can be attributed to the strong electric fields of the pump and probe light pulses. After the initial changes are over, the position and the width of the 750 cm−1 band change gradually to their stationary values until about 30 ps. These changes are probably due to the cooling of the solute–solvent system. Similar changes are recorded for two other Raman bands at 993 and 1018 cm−1.
Comparative Raman, infrared and optical spectroscopic studies of thin films of an axially substituted phthalocyanine compound
Authors: Wijekoon W. M. K. P. , Kama S. P. 
Published: May 2005

AbstractA series of thin films of an axially substituted silicon phthalocyanine, PcSi(OsiCH3C6H5OH)2, were made by spin coating and vacuum evaporation techniques. Electronics spectra of these films exhibit a bathochromic shift of the Q band compared with that of a chloroform solution. This bathochromic shift is ascribed to the formation of aggregates in films as seen by the scanning electron micrographs of them. Neither electronic nor vibrational spectra provide evidence for the formation of cofacial dimers which are usually found in evaporated films of axially substituted silicon phthalocyanines. The evaporated films that are redissolved in chloroform exhibit the same electronic and proton NMR spectra as the fresh solutions. The Raman and infrared spectra suggest that both evaporated and spin‐coated films possess similar molecular structures.
Raman characterization of an operating InAlAs—InGaAs—InP high electronic mobility transistor
Authors: Matrullo N. , Constant M. , Sagon G. , Fauquembergue R. , Leroy A. 
Published: May 2005

AbstractRaman scattering was used to probe electronic properties in In‐based structures. First, Raman signatures of undoped and doped InAlAs and InGaAs bulk materials and Raman spectra of InAlAs—InGaAs heterostructures were recorded. Raman scattering by coupled longitudinal optic phonons and two‐dimensional electron gas provides a powerful probe of electronic properties in this structure. More precisely, Raman results allowed information to be obtained on the two‐dimensional gas electron carrier concentration. Then, a specific advantage of the micro‐Raman method was demonstrated by the observation of the carrier concentration the vicinity of the gate of an operating high electronic mobility transistor (HEMT). Qualitative variations of carrier concentration in the two‐dimensional electron gas were observed and compared successfully with carrier concentration calculations using Monte Carlo simulations.
Spectra and structures of silicon‐containing compounds. XX—Raman and infrared spectra, conformational stability, vibrational assignment and ab Initio calculations of methylvinyldifluorosilane
Authors: Durig J. R. , Guirgis Gamil A. , Qtaitat Mohammad A. 
Published: May 2005

AbstractThe Raman (3100—10 cm−1) and infrared (3100—40 cm−1) spectra of methylvinyldifluorosilane, CH2CHSiF2CH3, were recorded for the gas and solid. Additionally, the Raman spectrum of the liquid was recorded and qualitative depolarization values were obtained. The observed bands in the fluid states are assigned on the basis of the more stable gauche (antiperiplanar) conformer where one of the fluorine atoms is eclipsing the double bond and the less stable cis (synplanar) conformer. However, in the annealed crystalline solid, only the cis conformer remains. A complete vibrational assignment is proposed for both conformers based on infrared band contours, Raman depolarization data, group wavenumbers and normal coordinate calculations. The experimental stability, barriers to internal rotation, and fundamental vibrational wavenumbers are compared with those obtained from the ab initio calculations employing the RHF/3‐21G*, RHF/6‐31G* and MP2/6‐31G* basis sets and to the corresponding quantities obtained for some similar molecules.
Probing the effects of electrolytes on intermolecular interactions in solution by optical‐heterodyne detected Raman‐induced kerr effect spectroscopy (OHD‐RIKESH)
Authors: Deuel Hans P. , Cong Peijun , Simon John D. 
Published: May 2005

AbstractTime‐domain experimental femtosecond OHD‐RIKES results for electrolyte solutions (NaI and LiCIO4 in acetonitrile and ethyl acetate) are presented and discussed within the context of the molecular polarizability ellipsoid of the solvent. It is concluded that the anisotropic part of the liquid intermolecular potential is not significatly influenced by the addition of electrolytes, even at concentrations up to the saturation limit.
In situ resonance Raman spectra of carotenoids in bird's feathers
Authors: Veronelli M. , Zerbi G. , Stradi R. 
Published: May 2005

AbstractMicro resonance Raman spectra of a series of synthetic carotenoids and of a large number of bird's feathers which contain various kinds of carotenoids were analysed on the basis of the effective conjugation coordinate (ECC) theory. The data obtained on parrots provide the first structural data on the chemical nature of the pigments embedded in their feathers, and show that these pigments are unmethylated polyene molecules. Data on the molecular orientation of the carotenoids and on the presence of different pigments in the same feather are presented and discussed.
Raman non‐coincidence effect of the carbonyl stretching mode in confined polar liquids
Authors: Wallen S. L. , Nikiel L. , Lee Y.‐T. , Jonas J. 
Published: May 2005

AbstractThe Raman non‐coincidence effect of the symmetric C=O stretching band was measured in liquid acetone and N,N‐dimethylformamide confined to porous silica glasses prepared by the sol—gel process. The experiments were carried out both on bulk liquids and liquids confined to glasses with pore radii from 17—76 Å at 293 K. The value of the non‐coincidence was decreased with decreasing pore radius (R) and scaled approximately as 1/R. Additional information about the role of pore surface effects was obtained by measurements on the polar liquids confined to surface‐modified glasses when the surface hydroxyl groups were replaced by OSi(CH3)3 groups. The experimental data show that the non‐coincidence effect is independent of the pore size in surface‐modified glasses.
Association of newly synthesized major fl coat protein with infected host cell inner membrane
Authors: Smilowitz Henry , Carson John , Robbins Phillips W. 
Published: May 2005

AbstractThe bacteriophage fl major coat protein becomes associated with the host cell inner membrane very shortly after it is synthesized. Pulse‐chase experiments suggest that the virus is never stably associated with the host cell outer membrane; we propose that it passes directly from the inner membrane to the growth medium.
Recombination in yeast mitochondrial DNA
Authors: Shannon Charles , Rao Ayyagari , Douglass Stephen , Criddle R. S. 
Published: May 2005

AbstractWhen haploid yeast strains containing mitochondrial DNAs (mtDNAs) of different buoyant densities are mated, the resulting zygotes contain a mixed population of mitochondria and mitochondrial DNAs. During vegetative growth of diploid cells formed from such a cross between a petite strain with mtDNA of density 1.677 g cm−3 and a respiratory competent strain with mtDNA of density 1.684 g cm−3, mtDNAs with intermediate buoyant densities are obtained. Virtually all newly synthesized mtDNA in diploid ρ− progeny has the intermediate buoyant density. Therefore, within 2 generations of growth of the diploid cells, the intermediate buoyant density species predominate. In crosses between a respiratory competent strain and other petite strains with different values of genetic suppressiveness, it was found that the amount of recombination yielding mtDNAs of intermediate buoyant densities roughly parallels the degree of suppressiveness. Individual clones of respiratory deficient cells from such crosses were also isolated to confirm that stable mtDNAs with intermediate buoyant densities were obtained. Thus, it is apparent that some form of recombination takes place within the mtDNAs of yeast cells that results in stable mtDNA species.
Circular dichroism of biological membranes–brain microsomes
Authors: Long Marianna M. , Masotti Lanfranco , Sachs George , Urry Dan W. 
Published: May 2005

AbstractThe circular dichroism and absorption spectra of particulate and solubilized brain microsomes are reported. The corrected molar ellipticity for the membrane suspension was −1.1 × 10+4, between the values of axonal and oxyntic cell membranes and those for sarcotubular vesicles. No conformational change was detected which correlated unambiguously with the active cation transport function of these microsomes. Divalent cations, however, elicited a significant change in the membranes' ultra structure. Correction of suspension data for the NaI microsomes with and without sonication gave virtually identical values providing optimism for the corrections used and validating the difference in corrected values for ths suspension with and without magnesium. This indicates that, in addition to causing a change in the state of aggregation, 2 mM magnesium ion may reasonably be considered to effect a change in protein conformation.
Structural requirements for mitochondrial mutagenesis
Authors: Mahler Henry R. 
Published: May 2005

AbstractEthidium bromide (3, 8‐diamino‐5‐ethyl‐6‐phenylphenanthridinium bromide) and euflavine (3, 6‐diamino‐10‐methylacridinium chloride) are superficially similar in structure and ability to intercalate into DNA. However, they exhibit qualitative differences in their ability to bring about a mitochondrial mutation (ρ+ → ρ−) in Saccharomyces cerevisiae. This investigation tried to establish and compare the essential structural prerequisites in three series of planar, heterocyclic dyes: the phenanthridines (P series), the acridines (A series), and molecules with different heteroatoms related to acridines (X series). Compounds capable of bringing about the mutation in the complete absence of growth and energy sources are restricted to di‐primary amines in the P series: quaternization of the ring nitrogen, and an aromatic side chain at C‐6 also appear essential. Compounds in the A series are mutagenic only with growing cells; quaternization (C1 through C4) is essential. The 10‐allyl derivative is unusual; it is highly effective even in buffer supplemented only with an energy source. The results are interpreted in terms of a model that requires interaction of the mutagen with the mitochondrial inner membrane as well as with its DNA.