Proton affinity of proline and modified prolines using the kinetic method: role of the conformation investigated by <i>ab initio</i> calculations

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

doi:10.1002/rcm.1096

Cited by 25 publications

(45 citation statements)

References 69 publications

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“…. Molecules with higher polarizability usually have higher PAs . Thus, polarizabilities should decrease in the order of tyrosine > 3‐iodotyrosine > 3‐chlorotyrosine because lower PA implies reduced proton stabilization through intramolecular charge separation .…”

Section: Resultsmentioning

confidence: 99%

“…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%

“…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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Section: Resultsmentioning

confidence: 99%

“…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^{+}

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

Section: Experimental Partmentioning

confidence: 99%

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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“…In our case, it is difficult to determine the S°value because no significant change in effective temperature is observed in the ion-trap mass spectrometer 31 when the amplitude of the excitation voltage is increased. For the system of 2 0 -deoxyuridine with amino acids as reference bases, an average effective temperature of 404 š 16 K was reached.…”

Section: Proton Affinity Determination By the Kinetic Methodsmentioning

confidence: 94%

Proton affinity ladder for uridine and analogs: influence of the hydroxyl group on the sugar ring conformation

Mezzache¹,

Alvès²,

Pèpe³

et al. 2005

J. Mass Spectrom.

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A ladder of relative proton affinities (PA) for a series of modified uridines (e.g. araU, ddU, 5BrU, 5BrdU and 5IU) was established from competitive dissociations of proton-bound heterodimers using Cooks and co-workers' kinetic method. The studied heterodimers are constituted of a modified nucleoside and either an amino acid or a nucleoside with known PA value. These non-covalent heterodimers were prepared under electrospray conditions to be selected and dissociated into the ion-trap analyzer. These results allowed our PA ladder of uridine and deoxyuridine analogs substituted at the C-5 position in the uracil ring to be extended. From this scale, it was showed that the substitution of hydrogen atom at the C-2' position in the sugar ring by a hydroxyl group involves a decrease of about 7 kJ mol(-1). The experimental values for U, 5MeU, dU, 5MedU, ddU and araU are consistent with those obtained by DFT calculations (B3P86/6-31+G//B3LYP/6-31G(.)). Several neutral and protonated conformations of these compounds were considered, in particular the ring conformation of furanose and the orientation of the base with respect to the sugar ring. These calculated results showed the influence of sugar substituent on the conformation of the neutral form of theses nucleosides. However, the most stable protonated structure is the same for all the studied nucleosides except for araU, where the position of the anti 2'-OH group imposes a specific conformation.

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“…The thermochemical properties that the method can access include proton affinity [15][16][17], gas-phase basicity [17][18][19][20], ionization energy [21], and metal ion affinity [22][23][24] to name a few. It has also been found useful in the differentiation and determination of enantiomers [25][26][27][28][29] and isomers [29 -34] under sterically-controlled conditions.…”

mentioning

confidence: 99%

Isomeric discrimination and quantification of thyroid hormones, T₃ and rT₃, by the single ratio kinetic method using electrospray ionization mass spectrometry

Kumar

Jin

et al. 2010

J. Am. Soc. Mass Spectrom.

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The single ratio kinetic method is applied to the discrimination and quantification of the thyroid hormone isomers, 3,5,3=-triiodothyronine and 3,3=,5=-triiodothyronine, in the gas phase, based on the kinetics of the competitive unimolecular dissociations of singly charged transition-metal ion-bound trimeric complexes [M II (A)(ref*) 2 -H] ϩ (M II ϭ divalent transitionmetal ion; A ϭ T 3 or rT 3 ; ref* ϭ reference ligand). The trimeric complex ions are generated using electrospray ionization mass spectrometry and the ions undergo collisional activation to realize isomeric discrimination from the branching ratio of the two fragment pathways that form the dimeric complexesThe ratio of the individual branching ratios for the two isomers R iso is found strongly dependent on the references and the metal ions. Various sets are tried by choosing the reference from amino acids, substituted amino acids, and dipeptides in combination with the central metal ion chosen from five transition-metal ions (Co II , Cu II , Mn II , Ni II , and Zn II ) for the complexes in this experiment. The results are compared in terms of the isomeric discrimination for the T 3 /rT 3 pair. Calibration curves are constructed by relating the ratio of the branching ratios against the isomeric composition of their mixture to allow rapid quantitative isomer analysis of the sample pair. Furthermore, the instrument-dependence of this method is investigated by comparing the two sets of results, one obtained from a quadrupole ion trap mass spectrometer and the other from a quadrupole time-of-flight mass spectrometer. (J Am Soc Mass Spectrom 2010, 21, 14 -22)

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Proton affinity of proline and modified prolines using the kinetic method: role of the conformation investigated by ab initio calculations

Cited by 25 publications

References 69 publications

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

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

Proton affinity ladder for uridine and analogs: influence of the hydroxyl group on the sugar ring conformation

Isomeric discrimination and quantification of thyroid hormones, T₃ and rT₃, by the single ratio kinetic method using electrospray ionization mass spectrometry

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Proton affinity of proline and modified prolines using the kinetic method: role of the conformation investigated by ab initio calculations

Cited by 25 publications

References 69 publications

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

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

Proton affinity ladder for uridine and analogs: influence of the hydroxyl group on the sugar ring conformation

Isomeric discrimination and quantification of thyroid hormones, T3 and rT3, by the single ratio kinetic method using electrospray ionization mass spectrometry

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Isomeric discrimination and quantification of thyroid hormones, T₃ and rT₃, by the single ratio kinetic method using electrospray ionization mass spectrometry