10.1021/ac401370t.s001
Liuxi Chen
Liuxi
Chen
Shu-Hua Chen
Shu-Hua
Chen
David H. Russell
David H.
Russell
An Experimental
Study of the Solvent-Dependent Self-Assembly/Disassembly
and Conformer Preferences of Gramicidin A
American Chemical Society
2013
dielectric solutions
HDX measurements
GA dimeric species
dissociation
dimer ions
conformer preferences
helix
monomerization kinetics
CID
Conformer Preferences
Experimental Study
antiparallel
hydrogen bonds
equilibrium abundances
Gramicidin AThe
2013-08-20 00:00:00
Journal contribution
https://acs.figshare.com/articles/journal_contribution/An_Experimental_Study_of_the_Solvent_Dependent_Self_Assembly_Disassembly_and_Conformer_Preferences_of_Gramicidin_A/2384863
The solvent dependence of self-assembly/disassembly
kinetics and
conformer preferences of the gramicidin A (GA) dimer is investigated
using a combination of techniques, viz., electrospray ionization–ion
mobility–mass spectrometry (IM-MS), collision-induced dissociation
(CID), and hydrogen/deuterium exchange (HDX)-MS. IM-MS measurements
reveal that there are possibly three distinct GA dimeric species,
detected as sodium ion adduct ions [2GA + 2Na]<sup>2+</sup>, and these
are assigned as the parallel β-helix, antiparallel β-helix,
and head-to-head dimer. The monomerization kinetics and equilibrium
abundances of the dimer ions depend upon solvent polarity. The antiparallel
β-helix was the thermodynamically preferred species in less
polar solvents. HDX measurements and collision-induced dissociation
(CID) of the intermediate complex confirm the well-protected dimer
geometry with strong intermolecular hydrogen bonds. This combined
IM-HDX-CID methodology provides a comprehensive view of GA self-assembly/disassembly
in low dielectric solutions, showing its potential utility in solving
solution-phase protein self-assembly/disassembly kinetics and providing
structural information of the multimers at the same time.