Naslov
The Gas-Phase H/D Exchange Mechanism of Protonated Amino Acids

Autori
Rožman, Marko

Izvornik
Journal of the American Society for Mass Spectrometry (1044-0305) 16 (2005), 11; 1846-1852

Vrsta, podvrsta i kategorija rada
Radovi u časopisima, članak, znanstveni

Ključne riječi
Density Functional Theory ; Fourier Transform Mass Spectrometry ; H/D Exchange ; Protonated Amino Acids ; Reaction Mechanisms

Sažetak
A mass spectrometry and Density Functional Theory study of gas-phase H/D exchange in protonated Ala, Cys, Ile, Leu, Met and Val is reported. Site-specific rate constants were determined and results identify the α − amino group as the protonation site. Lack of exchange on the Cys thiol group is explained by the absence of strong intramolecular hydrogen bonding within the reaction complex. In aliphatic amino acids the presence of a methyl group at the β − C atom was found to lower the site-specific H/D exchange rate for amino hydrogens. Study of the exchange mechanism showed that isotopic exchange occurs in two independent reactions: in one only the carboxylic hydrogen is exchanged and in the other both carboxylic and amino group hydrogens exchange. The proposed reaction mechanisms, calculated structures of various species and a number of structural findings are consistent with experimental data.

Izvorni jezik
Engleski

Znanstvena područja
Kemija

POVEZANOST RADA