Carbon-13 Chemical Shifts Accompanying Helix Formation

1973 ◽  
Vol 51 (4) ◽  
pp. 460-464 ◽  
Author(s):  
James R. Lyerla Jr. ◽  
Brian H. Barber ◽  
Murray H. Freedman
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Glutamic Acid ◽  
Chemical Shifts ◽  
Biological Significance ◽  
Structure Change ◽  
Shielding Effect ◽  
Amino Terminal ◽  
Helix Formation ◽  
Coil Transition

The helix–coil transition in an aqueous solution of poly-L-glutamic acid has been observed using 13C nuclear magnetic resonance. The transition from coil to helix results in pronounced deshielding of the carbonyl and C-α carbons of the polymer and a less dramatic shielding effect on the C-β carbon. These results are contrasted with the titration behavior of L-glutamic acid to delineate those shifts directly attributed to the secondary-structure change. The biological significance of this observation is supported by the 13C chemical shift differences observed for the 13C-enriched phenylalanyl residue 8 in the free 1–15 amino-terminal peptide of ribonuclease (RNase) and the 1–15 peptide:RNase S-protein complex.

NOTIZEN: Use of 95Mo NMR for Identification of Molybdenum (VI) Chalcogenide Anions in Aqueous Solution

1977 ◽  
Vol 32 (5) ◽  
pp. 505-506 ◽  
Author(s):  
O. Lutz ◽  
A. Nolle ◽  
P. Kroneck
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Magnetic Resonance ◽  
Aqueous Solutions ◽  
Chemical Shifts ◽  
Magnetic Resonance Studies ◽  
Nuclear Magnetic

Abstract95Mo Fourier transform nuclear magnetic resonance studies were made on aqueous solutions of oxo thiomolybdates. Chemical shifts up to 2200 ppm were found for the different unambiguously assigned species MoO4-nSn2- (n = 0, 1, 2, 3, 4).

Aqueous solution interaction of the methylmercuric cation with the dinucleotides CpG and dCpdG as studied by carbon-13 nuclear magnetic resonance spectroscopy

1986 ◽  
Vol 64 (10) ◽  
pp. 2038-2041 ◽  
Author(s):  
G. W. Buchanan ◽  
M. J. Bell
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
The Self ◽  
Coupling Constants ◽  
Resonance Spectroscopy ◽  
Spectral Parameters ◽  
Guanine Base ◽  
Nuclear Magnetic

13C nuclear magnetic resonance chemical shifts and 13C–31P coupling constants are reported for the self-complementary dinucleotides CpG and dCpdG in aqueous solution. The influence of methylmercuration at pH 6.0 on these spectral parameters has been examined. Results are interpreted in terms of preferential methylmercuration at the N-7 site of the guanine base of each dinucleotide with concomitant base destacking.

The shielding effect of heterosubstituents in 13C nuclear magnetic resonance

1976 ◽  
Vol 54 (4) ◽  
pp. 632-641 ◽  
Author(s):  
H. Beierbeck ◽  
J. K. Saunders
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Shielding Effect ◽  
Dihedral Angles ◽  
13C Nuclear Magnetic Resonance ◽  
Shielding Effects ◽  
Nuclear Magnetic

The effect of a heterosubstituent X on 13C chemical shifts, in conformations characterized by dihedral angles of 60°, is analyzed in terms of α-shifts, heteroatom–carbon (XC), hydrogen–heteroatom (HX) and carbon–heteroatom (CX) gauche interactions, and nonbonded γ(X) and δ(X) interactions. The more general parameters [Formula: see text] describe the β-heteroatom shifts in conformations in which the dihedral angles [Formula: see text] differ from 60°. The shielding effects of chlorine, exocyclic oxygen, and endocyclic nitrogen are analyzed.

Nitrogen-14 nuclear magnetic resonance of the amino terminal group of leu-enkephalin in aqueous solution

1987 ◽  
Vol 75 (3) ◽  
pp. 513-516 ◽  
Author(s):  
Ioannis P Gerothanassis ◽  
Theodoros Karayannis ◽  
Maria Sakarellos-Daitsiotis ◽  
Constantin Sakarellos ◽  
Michel Marraud
Keyword(s):  
Aqueous Solution ◽  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Terminal Group ◽  
Amino Terminal ◽  
Nuclear Magnetic
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