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  • 1
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 2 (1996), S. 39-45 
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Infrared spectroscopy was applied to the investigation of normal and oxidatively modified hepatic nuclei. The hepatic nuclei were oxidized by two different free-radical-generating systems. Infrared spectra of oxidized nuclei were remarkably different from those of normal nuclei; the major alteration found in the spectra of oxidized nuclei was the emergence of a new population of nucleic acids with a hydrogen-bonding pattern different from that of the normal phosphodiester groups, and a redistribution of the hydrogen bonding of the protein amide groups of the histones, indicative of protein-structural rearrangements. The spectral changes in the phosphate bands of the nucleic acid resemble those previously observed in different types of malignant tissue, and suggest that there could be a link between nuclei oxidation and carcinogenesis which may involve a free-radical-mediated process. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Fourier transform infrared spectroscopy has been applied to the study of human breast tumors, human breast tumor cell lines and xenografted human tumor cells. The results presented indicate that substantial differences exist on a macroscopic level between human tumors, xenografted tumors and human tumor cell lines, which are related to the presence of a significant connective tissue matrix in the tumors. On a macroscopic level tumor cell xenografts appear, in spectroscopic terms, to be relatively homogeneous with a relatively weak signature characteristic of connective tissue. Differences on a microscopic level between adjacent small (30 μm2) areas of the same xenografted tumor could be detected, which were due to local variations in collagen content. In addition to variations in collagen content, variation in the deposition of microscopic fat droplets throughout both human and xenografted tumors could be detected. These results indicate the care with which infrared spectroscopic studies of tissues must be carried out to avoid incorrect interpretation of results due to an incomplete understanding of tissue pathology. © 1995 John Wiley & Sons, Inc.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1075-4261
    Keywords: near-IR ; protein folding ; denaturation ; ribonuclease A ; overtone and combination bands ; 2-dimensional correlation analysis ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: We introduce near-IR spectroscopy as an ancillary tool for monitoring structural changes of proteins in aqueous solution using ribonuclease A (RNase A) as a model protein. The thermal unfolding of RNase A results in clear spectral changes in the near-IR and the mid-IR regions. In the near-IR the most pronounced changes are observed in the spectral region between 4820 and 4940 cm-1. The strong N—H combination band found at 4867 cm-1 in the spectrum of native RNase A shifts to 4878 cm-1 upon thermal unfolding. Hydrogen-deuterium exchange experiments that validate the N—H character of this mode can also be used to estimate the number of unexchanged amide protons after exposure to D2O. The transition profiles and temperatures derived from the temperature dependence of the N—H combination mode were found to be practically identical with those derived from the temperature dependence of the C=O amide I band in the mid-IR region, demonstrating that the near-IR region can be used as a conformation-sensitive monitor for the thermally induced unfolding of proteins in H2O solution. A 2-dimensional correlation analysis was applied to the mid-IR and near-IR spectra of RNase A to establish correlations between IR bands in both regions. The correlation analysis demonstrates that the thermal unfolding of RNase A is not a completely cooperative process; rather it begins with some changes in β-sheet structure, followed by the loss of α-helical structures, and then ending with the unfolding of the remaining β-sheets. © 1998 John Wiley & Sons, Inc. Biospectroscopy 4: S19-S29, 1998
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The Raman spectrum of aqueous palmitoyl lysolecithin was monitored as a function of pressure between 1 bar and 26.1 kbar. The changes observed in these Raman spectra are discussed in terms of the effect of hydrostatic pressure on the phase state and the molecular structure of lysolecithins. At pressures between 1 and 1900 bar aqueous palmitoyl lysolecithin exists in a micellar state and at pressures above 1.9 kbar it converts into a series of three coagel phases. The critical pressures at 28°C are 1.9 kbar for the micellar to coagel I transition, 4 kbar for the coagel I to coagel II transition and 15 kbar for the coagel II to coagel III transition. The transition from the micellar phase to the coagel I phase has a high pressure hysteresis of 1.1 kbar, while the transitions between the three coagel phases show only negligible pressure hysteresis. The major change in structure occurs at 1.9 kbar where the cylindrical micellar phase converts to an interdigitated lamellar coagel phase; the structural changes at 4 kbar (coagel I/II transition) and at 15 kbar (coagel II/III transition) involve only a modification of the interchain packing.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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