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  • 1995-1999  (5)
  • 1985-1989  (6)
  • 1960-1964
  • 1890-1899
  • 1840-1849
  • Analytical Chemistry and Spectroscopy  (11)
  • 1
    Electronic Resource
    Electronic Resource
    Modeling the heme vibrational spectrum: Normal-mode analysis of nickel (II) etioporphyrin-I from resonance raman, ft-raman, and infrared spectra of multiple isotopomers (1995)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 1 (1995), S. 395-412 
    Details
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Nearly complete vibrational assignments have been obtained for a heme model, nickel etioporphyrin-I (NiEPI), using variable-wavelength resonance Raman (RR), and FT-Raman (FT-R), as well as infrared (IR) spectroscopy, on a series of isotopomers labeled at positions in the skeleton (15N, β-13C, meso-d4, 15N-meso-d4) and in the peripheral substituents (methyl-d12, ethyl-d8, and ethyl-d12). The vibrational bands are assigned to the porphyrin skeletal and substituent modes on the basis of the mode description scheme developed for nickel octaethylporphyrin (NiOEP) with the aid of a normal-mode analysis of NiEPI, explicitly including the peripheral substituents, i.e., the methyl and ethyl groups. The previously reported NiOEP force field was refined to account for the observed isotope shifts of NiEPI isotopomers. An important result is the requirement of relatively large, long-range force constants for methine bridge bonds on opposite sides of the porphyrin ring. These 1-8 and 1-9 interaction force constants are required to reproduce the frequencies and isotope shifts of six Cα-Cm stretching modes and especially to predict the relative order of the two highest-frequency Eu modes, v(Cα-Cm) (v38, ∼ 1570 cm-1) and v(Cβ-Cβ) (v37, ∼ 1600 cm-1). Most of the substituent (methyl and ethyl) vibrations are located in the RR and IR spectra. Strong RR enhancement of some substituent modes can be attributed to hyperconjugative interaction of the aliphatic groups with the porphyrin a1u orbital, as well as vibrational mixing of substituent modes with the nearby skeletal modes. © 1995 John Wiley & Sons, Inc.
    Additional Material: 15 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bspy.350010605
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  • 2
    Electronic Resource
    Electronic Resource
    Heme-protein interactions in cytochrome c peroxidase revealed by site-directed mutagenesis and resonance Raman spectra of isotopically labeled hemes (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 2 (1996), S. 365-376 
    Details
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Isotope labeling has been used to assign the resonance Raman spectra of cytochrome c peroxidase, expressed in Escherichia coli [CCP (MKT)], and of the D235N site mutant. 54Fe labeling establishes the coexistence of two separate bands (233 and 246 cm-1), arising from the stretching of the bond between the Fe atom and the proximal histidine ligand, His175. These are assigned to tautomers of the H-bond between the His175 imidazole NΓH proton and the Asp235 carboxylate side chain: In one tautomer the proton resides on the imidazole while in the other the proton is transferred to the carboxylate. When Asp235 is replaced by Asn, the H-bond is lost, and the Fe-His stretching frequency is markedly lowered. Two new RR bands are produced, at 205 and 185 cm-1, as a result of coupling between the shifted Fe-His vibration and a nearby porphyrin mode; the two bands share the 54Fe sensitivity expected for Fe-His stretching. C=C stretching and CβC=C bending vibrations have been separately assigned to the 2- and 4-vinyl groups of the protoheme prosthetic group via selective vinyl deuteration. In the acid form of the enzyme, the frequencies coincide for the two vinyl groups, at 1618 cm-1 for the C=C stretch, and at 406 cm-1 for the CβC=C bend. However, the 2-vinyl frequencies are elevated in the alkaline form of the enzyme, to 1628 cm-1 for C=C stretching, and to 418 cm-1 for CβC=C bending, while the 4-vinyl frequencies remain unshifted. Thus, the acid-alkaline transition involves a protein conformation change that specifically perturbs the 2-vinyl substituent. This perturbation might be a reorientation of the vinyl group, or an alteration of the porphyrin geometry that affects the porphyrin-vinyl coupling. The perturbation is attenuated when CO is bound to the enzyme; the C=C frequency is then unaffected in the alkaline form, while the CβC=C bending frequency is shifted to a smaller extent (412 cm-1). This attenuation is probably linked to inhibition of distal histidine binding to the heme Fe in the alkaline form when the CO is bound. © 1996 John Wiley & Sons, Inc.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Structural evolution of the heme group during the allosteric transition in hemoglobin: Insights from resonance raman spectra of isotopically labeled heme (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Biospectroscopy 2 (1996), S. 311-316 
    Details
    ISSN: 1075-4261
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Physics
    Notes: Visible resonance Raman spectra in the low-frequency region (200-500 cm-1) are reported for hemoglobin (Hb) reconstituted with heme that is deuterated at the meso carbon atoms (meso-d4). Spectra were obtained in the deoxy form and in the immediate photoproduct of the carbonmonoxide adduct, HbCO. The isotope shifts permit assignment of two out-of-plane modes, γ6 and γ7, and the in-plane skeletal mode ν8, as well as the well-known iron-histidine [Fe-His] stretching vibration. Important differences between deoxyHb and the immediate photoproduct include 1) a large upshift in the Fe-His frequency, from 216 to 228 cm-1, 2) an upshift in γ6 (349 to 353 cm-1) together with substantial diminution of the ν8 (341 cm-1) intensity, and 3) collapse of two γ7 bands (305 and 296 cm-1) to a single band at 304 cm-1. This last observation implies subunit heterogeneity in deoxyHb but not in the photoproduct. When these bands are monitored in the time-resolved RR spectra following HbCO photolysis, it is seen that subunit heterogeneity is first detectable in the 0.5-μs transient [intermediate S], which has been associated with the initial rearrangement of the subunits to form the T-state contacts, on the basis of ultraviolet RR spectroscopy.1 However the intensification of ν8 does not occur until the 17-μs transient (intermediate T′), in which the T-state contacts are locked in and the Fe-His bond is strained. Implications for the mechanism of Hb allostery are discussed. © 1996 John Wiley & Sons, Inc.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Fast atom bombardment mass spectra of low molecular weight alcohols and other compounds. Evidence for a chemical ionization process in the gas phaseThis paper was presented in part at the ASMS 35th Annual Conference on Mass Spectrometry. See Ref. 1. (1988)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 2 (1988), S. 21-23 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290020108
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  • 5
    Electronic Resource
    Electronic Resource
    Fast atom bombardment tandem mass spectrometry of the anti-parasitic agent pentamidine and its oxygenated metabolites (1995)
    Chichester : Wiley-Blackwell
    Biological Mass Spectrometry 30 (1995), S. 549-556 
    Details
    ISSN: 1076-5174
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Although pentamidine (1,5-bis(4′-amidinophenoxy)pentane) is currently in use for the treatment of a variety of parasitic infections, including acquired immune deficiency syndrome-related Pneumocystis carinii pneumonia, its metabolism is still under investigation. Positive-ion fast atom bombardment mass spectrometry was used with high-energy collision-activated dissociation (CAD) and linked scanning at constant B/E to obtain tandem mass spectra of protonated molecules of pentamindine and seven synthetic oxygenated derivatives, which are known metabolites of pentamidine. Charge-initiated fragmentation produced abundant fragment ions of m/z 120 and 137 and loss of neutral ammonia from the protonated analyte that characterized the amidinophenoxy group. The structures of isomeric 2-hydroxypentamidine, 3-hydroxypentamidine and N-hydroxypentamidine could be distinguished based on charge-remote fragmentation that produced a series of fragment ions of the pentyl chain and permitted the exact location of the hydroxyl group in each molecule to be determined. Next, tandem mass spectra were obtained and the charge-initiated and charge-remote fragmentation discussed for four other metabolites of pentamidine, including N,N′-dihydroxypentamidine, 5-(4′-amidinophenoxy)pentanoic acid, 5-(4′-amidinophenoxy) pentan-1-ol, and p-hydroxybenzamidine. Finally, tandem mass spectrometry was used to identify pentamidine and three pentamidine metabolites contained in high-performance liquid chromatographic (HPLC) fractions from rat liver perfusate and rat urine following treatment with pentamidine. Pentamidine metabolites identified in rat urine and liver perfusate using mass spectrometry and HPLC retention times included 2-hydroxypentamidine, 3-hydroxypentamidine and 5-(4′-amidinophenoxy)pentanoic acid.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jms.1190300405
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  • 6
    Electronic Resource
    Electronic Resource
    Comparison of the thiocarbonyl13C NMR resonances of N-phenylthioureas, N-phenyl thiocarbamates and N-phenyl dithiocarbamates (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 460-461 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 13C NMR spectra of N-phenylthioureas, N-phenyl thiocarbamates and N-phenyl dithiocarbamates of the ethyl and n-butyl type are compared. Significant differences are observed in the chemical shift of the thiocarbonyl carbon, which do not parallel the electronegativity of the bonded heteroatom.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240513
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  • 7
    Electronic Resource
    Electronic Resource
    H2 Raman-shifted YAG laser ultraviolet Raman spectrometer operating at wavelengths down to 184 nm (1986)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 17 (1986), S. 471-475 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Apparatus is described for the acquisition of Raman spectra with excitation at wavelengths as short as 184 nm. The H2 Raman-shifted output of an Nd:YAG laser is directed on to a free-flowing sample, and the Raman photons are collected and dispersed by a scanning 1.26 m single monochromator equipped with a 2400 groove holographic grating and a solar blind phototube with integrating electronics, or by a 0.5 m spectrograph with an 1800 groove holographic grating and a reticon multi-channel detector. Data for air-sensitive samples are obtained by enclosing the sample jet in an inert gas purged shroud equipped with a UV-transparent optical window. Raman spectra are reported for phenylalanine at a series of excitation wavelengths down to 184 nm. They show a sharp transition between 200 and 192 nm from vibronic to Franck-Condon scattering. At 200 nm, the intensities of the vibronically induced ν8a and ν8b modes, at 1606 and 1586 cm-1, are nearly the same as that of the 1000 cm-1 ν1 ring breathing mode, whereas at 192 nm the relative intensities of the former bands are dramatically dimished. In contrast, the ν8a and ν8b modes of tyrosine continue to show enhancement comparable to the ring breathing modes at 192 nm, the maximum of the strong 1Bα, b tyrosine absorption. The spectrum of insulin at 192 nm shows comparable contributions from tyrosine, phenylalanine and amide vibrations, whereas at 200 and 218 nm excitation the aromatic contributions are dominant.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250170609
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  • 8
    Electronic Resource
    Electronic Resource
    Raman difference spectroscopy via backscattering from a spinning tube and from a low-temperature tuning fork (1985)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 16 (1985), S. 432-437 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Two novel devices for difference Raman spectroscopy are described. In one, an NMR tube is fltted with a PTFE divider to permit difference spectroscopy via the convenient spinning tube backscattering arrangement. The other device is a tuning fork, equipped with a pair of sample cups, attached to a cold finger, to permit acquisition of difference spectra on small samples of frozen solutions. This provides a particularly convenient method for low-temperature difference spectroscopy.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250160613
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  • 9
    Electronic Resource
    Electronic Resource
    UV resonance Raman study of platinum binding to guanine in mono- and di-nucleotides (1988)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 19 (1988), S. 203-212 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ultraviolet resonance Raman UVRR spectra, with 240 and 218 nm excitation, are reported for complexes of cis-NH32Pt2+ with dGMP 2-deoxyguanosine 5′-monophosphate having H or D at C-8. Previously reported UVRR effects of Pt binding to G are confirmed and extended. Excitation profiles recorded throughout the UV region are reported, together with cross-sections for the perchlorate ion, used as an internal standard. The excitation profiles show strong losses in enhancement associated with Pt binding for most of the guanine G UVRR bands in resonance with the UV electronic transitions of G. Hypochromic effects are involved, associated with diminished transition dipole moments due to the N-7-bound Pt, as are changes in Franck-Condon products. A new, weak resonance is seen in the excitation profiles at ca 220 nm, and is attributed to a Pt → G metal-ligand chargetransfer transition. Because bands showing large frequency shifts on Pt binding are selectively enhanced by this transition, 218 nm is the best wavelength for monitoring Pt binding to G in UVRR spectra. Even at this wavelength, Raman contributions from uncomplexed G and also A tend to obscure the Pt-bound G spectrum, as shown by the spectra of the dinucleotides d(GpG) and d(ApG) complexed with Pt(dien)2+ (dien = diethylenetriamine), although a marker for Pt-bound G can still be detected. The 218 nm-excited spectrum of cis-Pt[d(GpG)N-7(1), N-7(2)] shows clear evidence of both N(C-3′-endo) and S(C-2′-endo) sugar conformations, and also intensity alterations which may be associated with the ‘head-to-head’ arrangement of the Pt-bound G residues.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250190311
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  • 10
    Electronic Resource
    Electronic Resource
    Ultraviolet resonance Raman enhancement of the carboxylate and guanidinium groups in amino acids (1989)
    Chichester [u.a.] : Wiley-Blackwell
    Journal of Raman Spectroscopy 20 (1989), S. 645-650 
    Details
    ISSN: 0377-0486
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Carboxylate and guanidinium groups of amino acids have been studied by ultraviolet resonance Raman (UVRR) spectroscopy. On near-resonant excitation (192 nm) into the allowed π-π* transition of the carboxylate chromophore, the vibrational spectrum of aspartate displays only one band originating from the COO- symmetric stretching mode, consistent with an A-term enhancement mechanism. The UVRR spectra of the guanidinium ion reveals a complex vibrational pattern, and the bands have been assigned with the aid of a normal coordinate analysis. UV enhancement is observed for both asymmetric (E′) and totally symmetric (A1′) modes, and also for the overtone of the out-of-plane CN3 bending mode, Γ(A2″). The E′ enhancement is suggested to reflect Jahn - Teller splitting in the first allowed electronic transition A2″ ← E″, whereas the 2Γ(A2″) enhancement requires a lowering of the force constant for out-of-plane bending in the excited state, consistent with its expected tendency toward pyramidalization. Similar enhancement patterns are seen in the UVRR spectra of the guanidinium chromophore in methylguanidinium and arginine, which show, in addition, splittings and intensity redistribution due to the substituents. The excitation profiles of guanidinium and arginine reveal a complex structure that may arise from an excited-state Jahn - Teller effect. The Raman enhancements are too low to permit detection of guanidinium or carboxylate in the UVRR spectra of proteins, even at wavelengths as low as 192 nm.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jrs.1250201003
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