Tailoring peptide conformational space with organic gas modifiers in TIMS-MS

Abstract

Recently, we showed the advantages of Trapped Ion Mobility Spectrometry for the study of kinetic intermediates of biomolecules as a function of the starting solvent composition (e.g., organic content and pH) and collisional induced activation. In the present work, we further characterize the influence of the bath composition (e.g., organic content) on the conformational space of an intrinsically disordered, DNA binding peptide: AT-hook 3 (Lys-Arg-Pro-Arg-Gly-Arg-Pro-Arg-Lys-Trp). Results show the dependence of the charge state distribution and mobility profiles by doping the solution and the bath gas with organic modifiers (e.g., methanol and acetone). The high resolving power of the TIMS analyzer allowed the separation of multiple IMS band per charge state, and their relative abundances are described as a function of the experimental conditions. The use of gas modifiers resulted in larger inverse mobilities, with a direct correlation between the size of the modifier and the 1/K0 differences. Conformational isomer inter-conversion rates were observed as a function of the trapping time. Different from solution experiments, a larger variety of organic gas modifiers can be used to tailor the peptide conformational space, since peptide precipitation is not a problem.