A Quantitative Basis for a Scale of Na⁺ Affinities of Organic and Small Biological Molecules in the Gas Phase

Abstract

High-pressure mass spectrometric experiments and ab initio calculations have been carried out in order to establish a series of accurate gas-phase sodium ion affinities of organic molecules with a wide variety of functional groups. Ab initio calculations have also been performed on the sodium complexes of three amino acids: serine, cysteine, and proline. A systematic critical evaluation of experimental and computational literature results shows that a significant number require revision. Based on comparisons with accurate experimental measurements, the ab initio procedure used is shown to yield sodium ion affinities with an accuracy of ca. 1 kcal‚mol -1 . This enables the construction of the first reliable table of gas-phase Na + affinities for organic and small biological molecules.

Gas phase H/D exchange of sodiated amino acids: Why do we see zwitterions?

“…To test the mechanism and increase the number of investigated sodiated amino acids in H/D exchange the gas-phase reactions of AlaNa [15][16][17][18][19][20]. Present findings, together with earlier results [10,11] indicate that in H/D exchange experiments only the ZW form of sodiated amino acid is probed.…”

Structure and property of glycine’s derivatives bound by multications (H+, Li+, and Na+): A theoretical study

“…After identifying the four ground states of the eleven different alkali metal-bound derivatives by HF/basis1 level optimizations 5 and by judgment, their geometries are refined at the B3P86/basis1 level 34 in order to obtain these results more accurately. All of these alkali metal-bound derivatives hold the Cs symmetries except VIЈ and IXЈ, which have C1 symmetries.…”

A density functional theory (DFT) study on gas-phase proton transfer reactions of derivatized and underivatized peptide ions generated by matrix-assisted laser desorption ionization

“…Proton affinities have been mostly determined measuring the equilibrium constants for gas-phase proton transfer between two bases. In the last decade, introduction of computational chemistry based methods has provided an alternative way to determine accurately the proton affinities of single amino acids [19,20] and sodium affinities of small organic molecules [21]. Thermochemical properties of various UV and IR matrices were evaluated by means of B3LYP density functional molecular orbital calculations [22].…”