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Gas-phase water assisted conformational changes of the cationized amino acids

Rožman, Marko; Srzić, Dunja; Klasinc, Leo
Gas-phase water assisted conformational changes of the cationized amino acids // 17th Intrenational Mass Spectrometry Conference
Prag, Republika Češka, 2006. (poster, međunarodna recenzija, sažetak, znanstveni)

Gas-phase water assisted conformational changes of the cationized amino acids

Rožman, Marko ; Srzić, Dunja ; Klasinc, Leo

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

17th Intrenational Mass Spectrometry Conference

Mjesto i datum
Prag, Republika Češka, 27.08.-01.09.2006

Vrsta sudjelovanja

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Gas-phase interaction; H/D exchange; reaction mechanism; DFT; FTICR MS

In the field of hydrated gas-phase ions the search for the “ Holy Grail” is to pinpoint the number of molecules needed to stabilize the ZW form of (cationized) amino acid. Currently stabilization of the cationized amino acid ZW form is treated mostly as successive addition of water molecules. New insights might be gained viewing at the problem “ dynamically” by investigating the interacting partners and potential energy profiles of water assisted conformational changes. In this work gas-phase interaction of cationized amino acids with D2O is investigated by combining results of H/D exchange reactions measured in the FTICR mass spectrometer with those from density functional theory and molecular dynamics calculations. Analysis of sodiated amino acids and its interactions with water shows that prior to H/D exchange a structure perturbation occurs from the CS into the ZW form. In this perturbation, in which water acts as a catalyst, one single molecule of water suffices to produce the ZW form. This ZW form of amino acid is stable in the gas-phase because of the large barrier for ZW-CS conversion in the absence of water. The question now arises if the same is true for protonated amino acids with an extra amino group. However, for interaction of protonated lysine with D2O both experimental and theoretical findings suggest that isotopic exchange is favored over the water assisted conformational change from ion-molecule into ion-zwitterion structure.

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Projekt / tema

Institut "Ruđer Bošković", Zagreb