Proton affinity of diastereoisomers of modified prolines using the kinetic method and density functional theory calculations: role of the cis/trans substituent on the endo/exo ring conformation

Mezzache, S.; Pèpe, Claude; Karoyan, Philippe; Fournier, Françoise; Tabet, Jean‐Claude

doi:10.1002/rcm.2049

Cited by 12 publications

(5 citation statements)

References 24 publications

(36 reference statements)

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“…This underlines the advantage of using both ion trap and triple quadrupole instruments in combination with the kinetic method:2, 3 the resulting proton affinity and entropy values will become more reliable and more accurate. Recently, the determination of the PA of proline and its derivates using experimental14, 16, 29 and theoretical methods14, 16, 29–31 has been especially scrutinized in several publications. It is noteworthy that the calculated PA values of the proline and modified prolines present a satisfying agreement with the experimental results obtained here.…”

Section: Resultsmentioning

confidence: 99%

Improved proton affinity measurements for proline and modified prolines using triple quadrupole and ion trap mass spectrometers

et al. 2005

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Proton affinity (PA) of compounds such as proline, cis-3-methylproline, cis-3-ethylproline, cis-3-isopropylproline and cis-3-isopentanylproline was determined by kinetic method with amines as the reference bases. The effective temperatures determined using ion trap and triple quadrupole mass spectrometers were found to be significantly different. In the case of the triple quadrupole instruments, the effective temperature depends significantly on the collision energy. The influence of the apparent basicity (GBapp) on the effective temperature may be used to estimate the difference in protonation entropy (DeltaDeltaS degrees) between the sample and reference compounds. In case of the ion trap mass spectrometer, the variation of the effective temperature as a function of the excitation amplitude is small, so it is difficult to account for the contribution of the entropy effects to the proton affinity value. A better estimation of the PA and DeltaDeltaS degrees values for the investigated molecules is obtained by combining the GBapp and Teff data pairs that are obtained from both the mass spectrometers.

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Section: Resultsmentioning

confidence: 99%

Improved proton affinity measurements for proline and modified prolines using triple quadrupole and ion trap mass spectrometers

et al. 2005

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“…For H + , no calculations are required, and the only other non-zero energy term is the difference in translational energy, which was equal to 3/2 RT ≈ 3.7 kJ mol −1 . 24–26 …”

Section: Methodsmentioning

confidence: 99%

Fragmentation pattern of amides by EI and HRESI: study of protonation sites using DFT-3LYP data

et al. 2018

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Amides are important natural products which occur in a few plant families. Piplartine and piperine, major amides in Piper tuberculatum and P. nigrum, respectively, have shown a typical N-CO cleavage when analyzed by EI-MS or HRESI-MS. In this study several synthetic analogs of piplartine and piperine were subjected to both types of mass spectrometric analysis in order to identify structural features influencing

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“…As detailed in previous studies , CID of precursor clusters yield two product ions

false[A_{0} ∙ A_{i} false] ∙ H^{+} \overset{k_{0}}{false\to} A_{0} ∙ H^{+} + A_{i}

false[A_{0} ∙ A_{i} false] ∙ H^{+} \overset{k_{i}}{false\to} A_{0} + A_{i} ∙ H^{+}

where A 0 is the molecule with unknown PA (tyrosine, 3‐chlorotyrosine, or 3‐iodotyrosine), A i is the reference molecule with known PA (valine, isoleucine, threonine, phenylalanine, or methionine), and k is the dissociation rate constant. PA of A 0 is obtained using the linear equation

ln \frac{I_{0}}{I_{i}} = - \frac{P A_{i}}{R T_{normaleff}} + \frac{P A_{0}}{R T_{normaleff}}

where I is the mass spectral intensity, R is the ideal gas constant, and T eff is the effective temperature of the dissociating precursor. The assumption in this equation is that the ratio of mass spectral intensities I 0 / I i represents the ratio of rate constants k 0 / k i .…”

Section: Experimental Partmentioning

confidence: 99%

“…where A 0 is the molecule with unknown PA (tyrosine, 3-chlorotyrosine, or 3-iodotyrosine), A i is the reference molecule with known PA (valine, isoleucine, threonine, phenylalanine, or methionine), and k is the dissociation rate constant. PA of A 0 is obtained using the linear equation [3][4] [6][8] [12] ln…”

Section: Experimental Partmentioning

confidence: 99%

“…Several researchers have investigated the effect of chemical or structural modification on proton affinities (PAs) of biologically relevant molecules. In general, there is a positive correlation between intermolecular hydrogen‐bonding interaction or polarizability and PA ; the excess positive charge is strongly bound to the molecule through attractive hydrogen‐bonding interactions, and increased polarizability provides additional stabilization to the electronic structure of the protonated molecule.…”

Section: Introductionmentioning

confidence: 99%

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Kinetic Method Analysis of the Effect of Halogenation on Relative Proton Affinity of Tyrosine

Gannamani

Shin

2016

Helv. Chim. Acta

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Relative proton affinities (PAs) of tyrosine, 3‐chlorotyrosine, and 3‐iodotyrosine were obtained using the kinetic method approach. The measured mean values are 922.5, 912.9, and 917.9 kJ/mol, respectively, with ± 0.1 kJ/mol standard deviation, indicating that halogenation of tyrosine decreases its PA. In general, PA of a molecule increases as its isotropic polarizability increases, but no such correlation has been found for the three molecules investigated in this study. Our findings show that PA decreases with increasing electronegativity of the modifying atom for a halogenated molecule, further supporting computational results of previous work [5].

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Proton affinity of diastereoisomers of modified prolines using the kinetic method and density functional theory calculations: role of the cis/trans substituent on the endo/exo ring conformation

Cited by 12 publications

References 24 publications

Improved proton affinity measurements for proline and modified prolines using triple quadrupole and ion trap mass spectrometers

Improved proton affinity measurements for proline and modified prolines using triple quadrupole and ion trap mass spectrometers

Fragmentation pattern of amides by EI and HRESI: study of protonation sites using DFT-3LYP data

Kinetic Method Analysis of the Effect of Halogenation on Relative Proton Affinity of Tyrosine

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