title: Conformations of Prolyl-Peptide Bonds in the Bradykinin 1-5 Fragment in Solution and in the Gas Phase.
abstract: The dynamic nature of intrinsically disordered peptides makes them a challenge to characterize by solution-phase techniques. In order to gain insight into the relation between the disordered state and the environment, we explore the conformational space of the N-terminal 1-5 fragment of bradykinin (BK[1-5](2+)) in the gas phase by combining drift tube ion mobility, cold-ion spectroscopy, and first-principles simulations. The ion-mobility distribution of BK[1-5](2+) consists of two well-separated peaks. We demonstrate that the conformations within the peak with larger cross-section are kinetically trapped, while the more compact peak contains low-energy structures. This is a result of cis-trans isomerization of the two prolyl-peptide bonds in BK[1-5](2+). Density-functional theory calculations reveal that the compact structures have two very different geometries with cis-trans and trans-cis backbone conformations. Using the experimental CCSs to guide the conformational search, we find that the kinetically trapped species have a trans-trans configuration. This is consistent with NMR measurements performed in a solution, which show that 82% of the molecules adopt a trans-trans configuration and behave as a random coil.
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Liudmila
authors.initials: L
authors.lastname: Voronina
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Antoine
authors.initials: A
authors.lastname: Masson
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Kamrath
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft , D-14195 Berlin, Germany.
authors.forename: Franziska
authors.initials: F
authors.lastname: Schubert
authors.affiliation: Department of Chemistry, Indiana University , Bloomington, Indiana 47405, United States.
authors.forename: David
authors.initials: D
authors.lastname: Clemmer
authors.affiliation: Fritz-Haber-Institut der Max-Planck-Gesellschaft , D-14195 Berlin, Germany.
authors.forename: Carsten
authors.initials: C
authors.lastname: Baldauf
authors.affiliation: Laboratoire de Chimie Physique Moléculaire, École Polytechnique Fédérale de Lausanne, EPFL SB ISIC LCPM , Station 6, CH-1015 Lausanne, Switzerland.
authors.forename: Thomas
authors.initials: T
authors.lastname: Rizzo
mesh_terms: D001920:Bradykinin / Q000737:chemistry*; D005740:Gases / Q000737:chemistry*; D008958:Models, Molecular; D010446:Peptide Fragments / Q000737:chemistry*; D011487:Protein Conformation; D012996:Solutions; D013237:Stereoisomerism; D013816:Thermodynamics
chemical_list: D005740:Gases; D010446:Peptide Fragments; D012996:Solutions; C079000:bradykinin (1-5); D001920:Bradykinin