A 1H and 13C nuclear magnetic resonance study of carnosine

1986 ◽  
Vol 64 (11) ◽  
pp. 2132-2138 ◽  
Author(s):  
Jan O. Friedrich ◽  
Roderick E. Wasylishen
Keyword(s):  
Chemical Shifts ◽  
Imidazole Ring ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Basic Solution ◽  
Magnetic Resonance Study ◽  
Nmr Spectrum ◽  
13C Nuclear Magnetic Resonance ◽  
Nmr Techniques ◽  
C Nmr

The proton and carbon-13 resonance signals of carnosine (β-alanyl-L-histidine) were unambiguously assigned using a variety of nmr techniques including proton–carbon chemical shift correlations, titrations of nmr chemical shifts, coupling constants, and isotope shifts. From the 13C nmr titration, carnosine's three pKa values were estimated to be 2.7, 7.1, and 10.6, and it was found that the imidazole ring existed predominantly as the 3-H tautomer in basic solution. Conformational information about the Cα—Cβ bond and about the N—Cα bond was deduced from observed 3J(C,H) and 3J(H,H) values. The 13C nmr spectrum of carnosine in solution is also compared with that obtained for a solid sample.

Paramagnetic effects in flavin spectroscopy. A 13C nuclear magnetic resonance study

1978 ◽  
Vol 56 (8) ◽  
pp. 1045-1051 ◽  
Author(s):  
Donald David Macmurchie ◽  
Robert John Cushley
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Paramagnetic Species ◽  
Basic Solution ◽  
Line Broadening ◽  
Magnetic Resonance Study ◽  
Nmr Spectrum ◽  
13C Nuclear Magnetic Resonance ◽  
Specific Line ◽  
C Nmr

Experiments are described whose results indicate that semiquinones produced by intramolecular photoreduction of FMN in basic solution are responsible for specific line broadening observed in the 13C nmr spectrum. Tests with oxidizing agents as well as singlet and triplet quenchers are shown to support this theory rather than the proposition that the paramagnetic species effective in relaxation enhancement is a flavin triplet state. A mechanism for the production of semiquinones and their interaction with the FMN population is discussed.

13C nuclear magnetic resonance study of cyclodipeptides containing 13C enriched hydrophobic amino acids

1980 ◽  
Vol 45 (2) ◽  
pp. 482-490 ◽  
Author(s):  
Jaroslav Vičar ◽  
François Piriou ◽  
Pierre Fromageot ◽  
Karel Bláha ◽  
Serge Fermandjian
Keyword(s):  
Amino Acids ◽  
Nuclear Magnetic Resonance ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Side Chain ◽  
Amino Acid Residues ◽  
Magnetic Resonance Study ◽  
Side Chain Conformation ◽  
13C Nuclear Magnetic Resonance ◽  
Hydrophobic Amino Acids

The diastereoisomeric pairs of cyclodipeptides cis- and trans-cyclo(Ala-Ala), cyclo(Ala-Phe), cyclo(Val-Val) and cyclo(Leu-Leu) containing 85% 13C enriched amino-acid residues were synthesized and their 13C-13C coupling constants were measured. The combination of 13C-13C and 1H-1H coupling constants enabled to estimate unequivocally the side chain conformation of the valine and leucine residues.

Fe(CO)3 and Rh(acac) complexes of ergosteryl and 7-dehydrocholesteryl acetates: A high field nuclear magnetic resonance study

1988 ◽  
Vol 66 (12) ◽  
pp. 3003-3011 ◽  
Author(s):  
Richard E. Perkier ◽  
Michael J. Mcglinchey
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
High Field ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Two Dimensional ◽  
Magnetic Resonance Study ◽  
Anisotropic Properties ◽  
Diene System ◽  
Nmr Techniques

The 500 MHz 1H and 125 MHz 13C spectra of ergosteryl and 7-dehydrocholesteryl acetate were recorded in C6D6 and CDCl3 and assigned using two-dimensional NMR techniques. It is shown that incorporation of an Fe(CO)3 or a Rh(acac) moiety onto the ring B diene system affects the chemical shifts of neighbouring protons and carbons. These changes are discussed in terms of the anisotropic properties of the organometallic fragments.

A 1H and 13C nuclear magnetic resonance study of nucleosides with methylated pyrimidine bases

1982 ◽  
Vol 60 (24) ◽  
pp. 3026-3032 ◽  
Author(s):  
Frank E. Hruska ◽  
Wayne J. P. Blonski
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Chemical Shifts ◽  
Nuclear Magnetic Resonance Study ◽  
Coupling Constants ◽  
Magnetic Resonance Data ◽  
Proton Coupling ◽  
13C Nuclear Magnetic Resonance ◽  
Pyrimidine Bases ◽  
Nuclear Magnetic

Alkylated pyrimidine bases are of interest from the viewpoint of mutagenesis and carcinogenesis. 1H nuclear magnetic resonance data are presented for a series of ribosides and arabinosides alkylated at the O2,O4, N3, and C5 positions of the pyrimidine base. The data provide information about the stereochemical effects of base methylation. The J(5—6) proton coupling constants show that O-alkylation leads to a decrease in the π-bond order of the C5—C6 bond. The 13C chemical shifts are related to the tautomeric changes effected by O-alkylation.

1H and 13C nuclear magnetic resonance study of the complexation of uranyl ion with malic acid

1982 ◽  
Vol 60 (8) ◽  
pp. 1007-1018 ◽  
Author(s):  
M. Teresa Nunes ◽  
Victor M. S. Gil ◽  
António V. Xavier
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Malic Acid ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Molar Ratios ◽  
Nmr Study ◽  
13C Nuclear Magnetic Resonance ◽  
Ph Range ◽  
C Nmr

A full pH range 1H and 13C nmr study was performed of the complexation of UO22+ with malic acid, for variable concentrations and molar ratios. Spectral evidence for the existence of at least five complexes was found, and their stoichiometry and dependence on pH were investigated. Information on the conformation of the bound ligand molecules was also obtained.

scholarly journals An Experimental Study of the 4hJ(31P–31P) Coupling Constant and the 12C/13C Isotope Effect on 31P in an Iminophosphorane-Substituted Proton Sponge

2002 ◽  
Vol 2002 (1) ◽  
pp. 34-36
Author(s):  
José Elguero ◽  
Alain Fruchier ◽  
María Luisa Jimeno ◽  
Pedro Molina
Keyword(s):  
Experimental Study ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Coupling Constant ◽  
Proton Sponge ◽  
Nmr Spectrum ◽  
13C Isotope ◽  
C Nmr

The 13C NMR spectra of the bromide of the protonated iminophosphorane -substituted sponge 7 were recorded at different fields. Together with the use of 13C satellites of the 31P NMR spectrum, these experiments allow determination of a reasonable set of chemical shifts and coupling constants. The most interesting are a 4h JPP = 1.6 Hz, determined directly from the 31P NMR spectrum, which probably involves the hydrogen bond, and a 2Δ31P(13C) isotope shift of 9 ppb.

Hindered Rotation in Poly(N-acyl)iminoalkylenes - A 13C Nuclear Magnetic Resonance Study

1995 ◽  
Vol 50 (9) ◽  
pp. 1404-1411 ◽  
Author(s):  
Bernabé L. Rivas ◽  
Klaus Albert ◽  
Kurt E. Geckeler ◽  
Ernst Bayer
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
Cationic Polymerization ◽  
Nmr Spectra ◽  
Nuclear Magnetic Resonance Study ◽  
Side Chain ◽  
Magnetic Resonance Study ◽  
Hindered Rotation ◽  
13C Nuclear Magnetic Resonance ◽  
C Nmr

AbstractPoly(N-acetyl)iminoethylene. poly(N-propionyl)iminoethylene and poly(N-acetyl)-2,2-dimethyliminoethylene were prepared by cationic polymerization in solution of 2-methyl- 2-oxazoline, 2-ethyl-2-oxazoline, and 2,4,4-trimethyl-2-oxazoline respectively. The 13C NMR spectra of the polymers obtained showed different sets of shifts for the carbon atoms of the backbone as well as for the N-acylimino side chain due to the restricted rotation of the Nacylimino group. The temperature dependence of the N-acylimino side chain signals showed a different coalescence behaviour depending on the substituents at both the main and the side chain.

A 1H and 13C nuclear magnetic resonance study of silicon and germanium chalcogenide derivatives

1979 ◽  
Vol 57 (24) ◽  
pp. 3253-3256 ◽  
Author(s):  
John E. Drake ◽  
Boris M. Glavinćevski ◽  
Robyn Humphries ◽  
Abdul Majid
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Magnetic Resonance ◽  
General Pattern ◽  
Nuclear Magnetic Resonance Study ◽  
Magnetic Resonance Study ◽  
Methyl Substitution ◽  
Nmr Parameters ◽  
13C Nuclear Magnetic Resonance ◽  
Silicon And Germanium ◽  
C Nmr

This paper reports the 1H and 13C nmr parameters of the disilyl- and digermyl-chalcogenide species (MenH3−nM)2E, where M = Si, Ge; E = O, S, Se, Te and n = 0 to 3. The general pattern of changing shifts is markedly influenced by methyl substitution.

Carbon-13 and nitrogen-14 NMR spectra of 1-(substituted phenyl)pyridinium salts

1980 ◽  
Vol 45 (10) ◽  
pp. 2766-2771 ◽  
Author(s):  
Antonín Lyčka
Keyword(s):  
Heavy Water ◽  
Nmr Spectra ◽  
Chemical Shifts ◽  
Coupling Constants ◽  
Pyridinium Salts ◽  
Nmr Signals ◽  
C Nmr

The 13C and 14N NMR spectra of 1M solutions of 1-(substituted phenyl)pyridinium salts (4-CH3, 4-OCH3, H, 4-Cl, 4-Br, 4-I, 3-NO2, 4-NO2, 2,4-(NO2)2 (the 13C NMR only)) have been measured in heavy water at 30 °C. The 13C and 14N chemical shifts, the 1J(CH) coupling constants, some 3J(CH) coupling constants, and values of half-widths Δ 1/2 of the 14N NMR signals are given. The 13C chemical shifts of C(4) correlate with the σ0 constants (δC(4) = (1.79 ± 0.097) σ0 + (147.67 ± 0.041)), whereas no correlation of the nitrogen chemical shifts with the σ constants has been found. The half-widths Δ 1/2 correlate with the σ0 constants (Δ 1/2 = (76.2 ± 4.9) σ0 + (106.4 ± 2.2)) except for 1-phenylpyridinium chloride.

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