The gas-phase H/D exchange mechanism of protonated amino acids

Rožman, Marko (2005) The gas-phase H/D exchange mechanism of protonated amino acids. Journal of The American Society for Mass Spectrometry, 16 (11). pp. 1846-1852. ISSN 1044-0305

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Abstract

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.

Item Type:	Article
Additional Information:	The final publication is available at Springer via http://dx.doi.org/10.1016/j.jasms.2005.07.024
Uncontrolled Keywords:	Density Functional Theory; Fourier Transform Mass Spectrometry; H/D Exchange; Protonated Amino Acids; Reaction Mechanisms
Subjects:	NATURAL SCIENCES > Chemistry
Divisions:	Division of Physical Chemistry
Depositing User:	Kristina Ciglar
Date Deposited:	26 Jan 2017 08:58
URI:	http://fulir.irb.hr/id/eprint/3346
DOI:	10.1016/j.jasms.2005.07.024

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