Magnetic Resonances of Protons in Ethyl Alcohol

Arnold, James T.

doi:10.1103/physrev.102.136

Cited by 196 publications

(41 citation statements)

References 20 publications

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“…This suggests that the NH proton of Tyr in LysVP, though four bonds removed from the a-NH3+ group, might be influenced by it. This could arise from an electric field gradient effect that would alter the coupling of the nitrogen quadrupole to the NH proton, or through a relaxation broadening (10,11), which would also explain the absence of a Cys-1 peak. Further experiments may clarify the origin of the broadening.…”

Section: Results and Discussion Assignment Of Peaksmentioning

confidence: 99%

Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin and Its Structural Implications

Dreele¹,

Brewster²,

Scheraga³

et al. 1971

Proc. Natl. Acad. Sci. U.S.A.

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The NMR spectra at 220 MHz of iysinevasopressin and its precursors were measured in dimethyl sulfoxide, and the peaks were assigned to specific protons. Information about hydrogen bonding was obtained from the temperature coefficients of the chemical shifts. With these data, and with several chemical-shift positions and coupling constants, structural information was derived for this polypeptide hormone.High-resolution nuclear magnetic resonance (NMR) studies offer the possibility of determining the conformations of macromolecules in solution (1). This method is applied here to the well-known octapeptide hormone lysine-vasopressin (LysVP) in deuterated dimethyl sulfoxide [2H]6Me2SO solution. The interpretation of the NMR spectrum of this polypeptide was aided materially by the availability of the blocked precursors (dipeptide to nonapeptide) used in the synthesis of LysVP, i.e., the changes in the spectrum in the progression from dipeptide to nonapeptide to LysVP provided information on the chemical shift of specific protons, as well as on changes in conformation as each amino acid residue is added.LysVP (I) has the following structure, in which the numbers indicate the positions of the individual amino acid residues:Cys-Tyr-Phe-Gln-Asn-Cys-Pro-Lys-Gly-NH2. The half-cys-1 2 3 4 5 6 7 8 9 tine residues in positions 1 and 6 are referred to as Cys-1 and Cys-6, respectively. MATERIALS AND METHODSLysVP was a purified synthetic preparation (2, 3) that possessed about 250 U/mg of rat pressor activity.t The following protected peptide intermediates were also used in this study:Abbreviations for amino acid residues and protecting groups are in accordance with the IUPAC-IUB Tentative Rules [J. Biol. Chem., 24, 2491Chem., 24, (1966 The proton NMR spectra were recorded on a Varian HR-220 spectrometer, and on a Varian HA-100 spectrometer using an internal lock and frequency sweep mode. The sample concentrations were 4-10 g/100 ml in (100 mol %) [2H]6Me2SO, that had been stored over molecular sieves. When the polypeptide concentration was varied in this range, no change in the spectra were detected. All chemical shifts are downfield from the internal standard tetramethylsilane. The temperatuie of the sample was controlled to ±2°C. Homonuclear spin-decoupling on the HR-220 spectrometer was done by the field sweep method, using a General Radio Co. 1107-A interpolation oscillator, and on the HA-100 by the frequency sweep method. The spectra were calibrated by the side-band technique.After the NMR measurements were completed, the LysVP solutions were bioassayed. No appreciable inactivation of the LysVP was detected. RESULTS AND DISCUSSION Assignment of peaksThe peaks of the NMR spectrum of LysVP were assigned by making use of the spectra of the blocked precursors, from the di-to the nonapeptide, together with information on the spectra of other oligopeptides and of the isolated amino acids. The latter could not be used by themselves because of the influence of charges on the a-NH3+ and a-COO-groups. However, an amino aci...

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Section: Results and Discussion Assignment Of Peaksmentioning

confidence: 99%

Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin and Its Structural Implications

Dreele¹,

Brewster²,

Scheraga³

et al. 1971

Proc. Natl. Acad. Sci. U.S.A.

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“…The expression (5) may be rewritten by the Cartesian coordinate x as (6) The kinetic energy of the system, T, is as shown by (10)…”

Section: Analysis Of Nmr Spectrum By Amentioning

confidence: 99%

Harmonic Oscillator Model for the Analysis of NMR Spectra of Di-substituted Benzenes

Shimizu¹,

Fujiwara²

1960

Bulletin of the Chemical Society of Japan

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“…Proton exchange in ethanol and in ethanol-water solutions has been investigated several times (10,21,(28)(29)(30)(31)(32) has the work been on a quantitative kinetic basis. In the latter (21), rates of acid-and…”

Section: Application To T H E System Ethanol-watermentioning

confidence: 99%

“…The rate of proton exchange is very susceptible to catalysis (21) and trace impurities (10,27 For personal use only.…”

Section: Fig 3 Variation Of ~/ T B O H W~t H [Hoh]mentioning

confidence: 99%

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Exchange Broadening of Spin–spin Triplets in Nuclear Magnetic Resonance Spectra. Application to the System Ethanol–water

Paterson¹

1963

Can. J. Chem.

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Using an extension of the method of R/IcConnell (I), a n expression is derived for the nuclear magnetic resonance spectrum of a hydroxyl proton in a -CH?OH group which is undergoing intermolecular exchange. A graphical method is presented which enables a rapid evaluation of 7 , the average lifetime of a hydroxyl proton between exchange events. Measurements of line widths and multiplet spacings in the n.m.r. spectra of ethanol-water solutions are interpreted in terms of the proton exchange reaction CzHbOH + HOH* + CzHbOH* + HOH, for which a value of 2.7 1. mole-' sec-1 a t 42&1° C is suggested a s an upper limit to the rate constant. THEORETICALThe quantitative description of exchange processes which modify the nuclear magnetic resonance spectrum of a system follows most easily from an appropriate modification of the Bloch phenomenological equations . This approach, first used by Gutowsky, where G is the complex moment u f i v in the xy plane; u and v are the transverse components of the macroscopic nuclear magnetic moment M along and perpendicular to the rotating magnetic field H I ; y is the nuclear magnetogyric ratio; Mo is the equilibrium value of M; p, is the fractional population of the j sites ( j = 1, 2, . . . , n ) ; 7r.j is the probability per unit time of a nucleus on a k site making a jump to a j site, and analogously for T G I ; and a, is given by where T 2 , and oj are the transverse relaxation time T2 and the Larmor frequency, respectively, of a nucleus on a j site, and w is the angular rotation frequency of H I . Thus C k T::G~ in equation [ I ]represents the rate of increase of G, due to transfer of magnetization from k t o j sites and C k T>'G, represents the corresponding rate of loss.Since jumps between two sites of the same types have no effect on the spectrum (1, 2 ) , ~?,1 and ~iE;1 are zero if j = k.Equation [ I ] may be applied to the n.m.r. spectra of alcohols containing the -CH20Hgroup. The hydroxyl protons of such compounds show a triplet spectrum (due to coupling

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Magnetic Resonances of Protons in Ethyl Alcohol

Cited by 196 publications

References 20 publications

Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin and Its Structural Implications

Nuclear Magnetic Resonance Spectrum of Lysine-Vasopressin and Its Structural Implications

Harmonic Oscillator Model for the Analysis of NMR Spectra of Di-substituted Benzenes

Exchange Broadening of Spin–spin Triplets in Nuclear Magnetic Resonance Spectra. Application to the System Ethanol–water

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