T. Solouki et al., Gas phase hydrogen deuterium exchange reactions of a model peptide: FT-ICRand computational analyses of metal induced conformational mutations, J AM SOC M, 12(12), 2001, pp. 1272-1285
Citations number
75
Categorie Soggetti
Spectroscopy /Instrumentation/Analytical Sciences
Journal title
JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY
We utilized gas phase hydrogen/deuterium (H/D) exchange reactions and ab in
itio calculations to investigate the complexation between a model peptide (
Arg-Gly-Aspa drop RGD) with various alkali metal ions. The peptide conforma
tion is drastically altered upon alkali metal ion complexation. The associa
ted conformational changes depend on both the number and type of complexing
alkali metal ions. Sodium has a smaller ionic diameter and prefers a multi
dentate interaction that involves all three amino acids of the peptide. Con
versely, potassium and cesium form different types of complexes with the RG
D. The [RGD + 2Cs - H](+) species exhibit the slowest H/D exchange reactivi
ty (reaction rate constant of similar to6 X 10(-13) cm(3) molecule(-1)s-(1)
for the fastest exchanging labile hydrogen with ND3). The reaction rate co
nstant of the protonated. RGD is two orders of magnitude faster than that o
f the [RGD + 2Cs - H](+). Addition of the first cesium to the RGD reduces t
he H/D exchange reaction rate constant (i.e., D-0) by a factor of seven whe
reas sodium reduces this value by a factor of thirty. Conversely, addition
of the second alkali metal ions has the opposite effect; the rate of Do dis
appearance for all [RGD + 2Met - H](+) species (Met drop Na, K, and Cs) dec
reases with the alkali metal ion size. (C) 2001 American Society for Mass S
pectrometry.