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  • Chemistry  (13)
  • Cytosine H6  (1)
  • Deuterium labeling  (1)
  • Heteronuclear NMR  (1)
  • Human parotid saliva  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Filtering methods for selection of singlet and doublet signals in NMR spectra of DNA oligomers (1994)
    Springer
    Journal of biomolecular NMR 4 (1994), S. 181-191 
    Details
    ISSN: 1573-5001
    Keywords: Filtering method ; Signal selection ; Cytosine H6 ; Optimized conditions ; NOESY ; Assignment of DNA ; HAL ; HOENOE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary The base proton (purine H8 and pyrimidine H6) resonances are key signals for the assignment of the proton resonances of DNA oligomers. They are classified into two groups, i.e., cytosine H6 signals, observed as doublets, and the other base proton signals, observed as singlets. Here we propose some experiments for distinguishing the cytosine H6 signals from the other base proton signals. Moreover, the ability of signal selection and the sensitivity as to signal detection were compared for all experiments, and the optimum conditions for spectral measurements were surveyed. Some of the experiments were employed as the NOESY detection pulse. Previously proposed experiments, such as HOENOE and HAL, were also used in the comparison.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00175246
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  • 2
    Electronic Resource
    Electronic Resource
    The use of heteronuclear cross-polarization for backbone assignment of 2H-, 15N- and 13C-labeled proteins: A pulse scheme for triple-resonance 4D correlation of sequential amide protons and 15N (1995)
    Springer
    Journal of biomolecular NMR 5 (1995), S. 323-326 
    Details
    ISSN: 1573-5001
    Keywords: Heteronuclear NMR ; Deuterium labeling ; Cross-polarization ; Triple-resonance experiment ; Pulse scheme
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Notes: Summary A new four-dimensional pulse scheme is described for the main-chain assignment of proteins by means of the J connectivity of the amide proton and nitrogen resonances of adjacent residues. Since the new experiment, 4D CP-HN(COCA)NH, involves heteronuclear cross-polarization for magnetization transfer from 13C=O to 15N via 13Cα, a relatively strong WALTZ-16 decoupling rf field is applied to 13Cα during magnetization transfer. Consequently, 13Cα is effectively decoupled from its attached 2H in the case of deuterated proteins, in the absence of a decoupling rf field for 2H. This efficiently improves the sensitivity of the experiment through 13C line narrowing. The experiment was performed on a randomly 60% deuterated protein, and the sensitivity of the final 4D spectrum was found to be excellent.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00211761
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  • 3
    Electronic Resource
    Electronic Resource
    Preliminary proton nuclear magnetic resonance studies of human saliva (1991)
    Springer
    Oral radiology 7 (1991), S. 7-11 
    Details
    ISSN: 1613-9674
    Keywords: Proton NMR ; Human parotid saliva ; Human submandibular saliva
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Summary-Proton NMR spectra of gustatory stimulated healthy human whole, parotid and submandibular and sublingual saliva were measured. The typical patterns of their spectra were obtained. Among these three kinds of fluids the parotid saliva which contains preferentially serous saliva presented a relatively well resolved spectrum with satisfactory signal to noise ratio in a given short time(30min.). For eight subjects of parotid saliva collected in the afternoon the marked increase in signal intensity in the methyl and methylene proton region of proteins(peptides)was observed as compared with those collected in the morning, reflecting the circadian rhythms in the protein concentration in saliva. On the other hand the methyl peak of lactic acid presented the opposite tendency, which might be also correlated with the circadian rhythms of the glucose metabolism of the parotid gland. The proton NMR spectra of three patients suspected of salivary gland disease were different from those of healthy subjects.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02351673
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  • 4
    Electronic Resource
    Electronic Resource
    The vibrational spectra and structure of poly (rA-rU). Poly (rA-rU) (1973)
    New York : Wiley-Blackwell
    Biopolymers 12 (1973), S. 799-816 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Infrared and Raman spectra of aqueous poly(rA-rU)·poly(rA-rU), the double-helical complex containing strands of alternating riboadenylate and ribouridylate residues, display significant differences from one another and from corresponding spectra of poly(rA)·poly(rU), the double-helical complex of riboadenylate and ribouridylate homopolymers. Parallel studies on the copolymer and homopolymer complexes by cesium sulfate density gradient centrifugation, ultraviolet absorption spectroscopy, hydrogenion titration, 1-N oxidation of adenine residues by monoperphthalic acid and X-ray diffraction reveal, however, that the geometry of base pairing between adenine and uracil is closely similar in each complex and apparently of the Watson-Crick type. Therefore the differences observed between vibrational spectra of poly (rA-rU)·poly (rA-rU) and poly(rA)·poly(rU) are not due to different base-pairing schemes but may be attributed to differences in vibrational coupling between vertically stacked bases. Vibrational coupling may also account for the differences between infrared and Raman spectra of the same complex. Thus, the present results indicate that infrared and Raman frequencies of RNA in the region 1750-1550 cm-1 should be dependent on the base sequence.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1973.360120409
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  • 5
    Electronic Resource
    Electronic Resource
    Infrared spectra of transfer ribonucleic acids. III. Fragments of formyl-methionine tRNA from Escherichia Coli (1971)
    New York : Wiley-Blackwell
    Biopolymers 10 (1971), S. 681-698 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Four fragments (named K, L, M, and N) of Escherichia coli formylmethionine transfer RNA have been prepared by a partial digestion with ribonuclease T1 followed by a chromatographic separation with a DEAE-Sphadex (A-25) column and then a DEAE-cellulose column. The fragment K is the anticodon fragment with 19 nucleotides (previously reported). L is a fragment with 57 nucleotides involving the 3′-terminal (CCA). M is a fragment with 51 nucleotides which is equal to L except that M lacks 6 nucleotides at the 3′-terminal. N is a fragment with 20 nucleotides which involved the 5′-terminal and corresponds to the complementary half to L. The infrared absorption spectrum has been observed of each of these fragments and two equimolar mixtures L + N and M + N in D2O solutions at several temperatures. The results indicate that at 37°C, K has about 4 hydrogen-bonded base-pairs, L about 11, and M about 13. On the other hand, fragment N is found to have only three weak G-C pairs. For both L + N and M + N, 15-17 strong base pairs are found. The observations give direct support to the clover-leaf structure and at the same time provide information on the stability of each of the four arms in the structure.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360100407
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  • 6
    Electronic Resource
    Electronic Resource
    Conformational difference in cation complexes of tetranactin in solution (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 2645-2657 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformational changes and binding behavior of tetranactin on complexation with sodium, potassium, rubidium, cesium, and ammonium ions were investigated by the measurements of proton magnetic resonance, ir, and Raman spectra. It has been clearly shown that alkali cations coordinate to the oxygen atoms of both the carbonyl group and the tetra-hydrofuran ring, but the ammonium ion coordinates only to the oxygen atom of the tetrahydrofuran. Among the alkali cations the potassium ion most strongly coordinates to the tetrahydrofuran oxygen atoms. The complexation with larger cations induces an expansion of the cavity of the macrocyclic ring of tetranactin and smaller cations contract the cavity. The evidence is revealed by the coupling constants of the methylene protons and the frequency separation between the carbonyl stretching vibrations of the ir- and Raman-active modes. The conformations of the cation complexes in the solid are maintained in solution but that of the cation free form is not.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360181102
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  • 7
    Electronic Resource
    Electronic Resource
    Proton magnetic resonance studies on conformation and association of oligo-γ-benzyl-L-glutamates in solution (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 2381-2402 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The proton magnetic resonance spectra of o-nitrophenylthio-tetra- and hexa-γ-benzyl-L-glutamate ethylamides have been measured at different concentrations in CDCl3 and CD22C1. The NH and α-CH resonances of the tetrapeptide show downfield shifts with increasing concentration, accompanying disappearance of their fine structure and line broadening. The apparent feature of chemical shifts against concentration is sigmoidal, and it can be interpreted by assuming the presence of a step or more of association-dissociation equilibria of tetrapeptide. With increasing concentration, small aggregates are formed by intermolecular hydrogen bonding, the size of which is not sufficiently large to exhibit critical micelle concentrations. In contrast to the tetrapeptide, the hexapeptide has constant chemical shifts of the NH and α-CH resonances, independent of concentration, which implies that only the unassociated molecules show observable sharp resonances. In the hexapeptide, the phenyl CH and benzyl CH2 groups of the side chains exhibit new resonances above certain critical concentrations, indicating the restriction of rotational freedom of the side chains in the aggregated states.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360241215
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  • 8
    Electronic Resource
    Electronic Resource
    Conformer equilibria of triostin A and its conformer-specific interaction with nucleic acid basesAbbreviations: A, 2′,3′,5′-tri-O-acetyladenosine; U, 1-cyclohexyluracil; G, 2′,3′,5′-tri-O-isobutyrylguanosine; C, 2′,3′-isopropylidene-5′-pyranylcytidine; DMSO-d6, hexadeute-riodimethylsulfoxide; Qun or Qx, quinoxaline carboxylic acid. (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 1959-1970 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A quinoxaline antibiotic triostin A has a bicyclic octadepsipeptide structure. Proton and carbon-13 nmr spectra showed the presence of two symmetrical conformations favoring polar and nonpolar solvents, respectively. They interconvert slowly on the nmr time scale, and this slow interconversion is due to the cooperative effects of the presence of the quinoxaline ring and the N-methyl peptide bonds. Reversal of the chirality of the disulfide bond as the origin of the slow exchange was excluded by the presence of two conformers for S-benzyltriostin A. Conformer 2, which favors the polar solvent, can form hydrogen-bonded complexes with purine nucleoside derivatives in organic solvents, but conformer 1 does not. The binding sites were elucidated and a mode of interaction with DNA proposed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200918
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  • 9
    Electronic Resource
    Electronic Resource
    Application of the two-dimensional nmr techniques on a des(Ala,Gly)-somatostatin analog (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2021-2031 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Two-dimensional nmr techniques have been carried out for the peak assignment of the spectrum of a somatostatin analog. Two-dimensional J-resolved spectroscopy simplified the rather broad and complicated spectrum to show the center of chemical shifts of each resonance and gave information on the coupling profiles. Another technique, two-dimensional spin-echo correlated spectroscopy, revealed the connectivities between protons which are correlated by weak spin-spin couplings. The combination of the results of these two complementary techniques made it possible for us to assign almost all peaks of the spectrum of the 11-residue somatostatin analog.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360200924
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  • 10
    Electronic Resource
    Electronic Resource
    Conformational studies of the pentapeptides with weak adrenocorticotropin (ACTH) activities by means of nuclear magnetic resonance spectroscopy (1981)
    New York : Wiley-Blackwell
    Biopolymers 20 (1981), S. 2203-2212 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The conformations of a pentapeptide L-His-L-Arg-L-Trp-Gly with weak adrenocorticotropin (ACTH) activity and its analogs, where each L-amino acid residue is substituted by D-residue, were investigated by means of proton and carbon-13 nmr spectroscopy on their DMSO-d6 solutions. The spectra indicated the presence of slowly exchangeable conformation isomers for D-Phe and D-Arg analogs, due to steric hindrance around the arginine residue. The activation energy of the hindered rotation of the arginine side chain was estimated to be more than 19 ∼ 20 kcal/mol. Spin-lattice relaxation times of carbon-13 nuclei also indicated slow segmental motion of the arginine side chain of the D analogs. An effect on proton chemical shifts by intermolecular electrostatic interaction between the arginine side chain and the C terminal carboxylic residue was observed. We did not observe, however, a direct correlation between pentapeptide activity and molecular conformation at this stage of the experiments.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1981.360201013
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