title: A hydrodynamic comparison of solution and gas phase proteins and their complexes.
abstract: The extent to which protein structures are preserved on transfer from solution to gas phase is a central question for native mass spectrometry. Here we compare the collision cross sections (Ω) of a wide range of different proteins and protein complexes (15-500 kDa) with their corresponding Stokes radii (RS). Using these methods, we find that Ω and RS are well correlated, implying overall preservation of protein structure in the gas phase. Accounting for protein hydration, a scaling term is required to bring Ω and RS into parity. Interestingly, the magnitude of this scaling term agrees almost entirely with the drag factor proposed by Millikan. RS were then compared with various different predicted values of Ω taken from their atomic coordinates. We find that many of the approaches used to obtained Ω from atomic coordinates miscalculate the physical sizes of the proteins in solution by as much as 20%. Rescaling of Ω estimated from atomic coordinates may therefore seem appropriate as a general method to bring theoretical values in line with those observed in solution.
authors.affiliation: Chemistry Research Laboratory, University of Oxford , South Parks Road, Oxford, Oxfordshire, OX1 3TA, United Kingdom.
authors.forename: Dominic
authors.initials: D
authors.lastname: Hewitt
authors.forename: Erik
authors.initials: E
authors.lastname: Marklund
authors.forename: David J
authors.initials: DJ
authors.lastname: Scott
authors.forename: Carol V
authors.initials: CV
authors.lastname: Robinson
authors.forename: Antoni J
authors.initials: AJ
authors.lastname: Borysik
mesh_terms: D005740:Gases / Q000737:chemistry*; D057446:Hydrodynamics; D013058:Mass Spectrometry; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*; D012996:Solutions; D013499:Surface Properties
chemical_list: D005740:Gases; D011506:Proteins; D012996:Solutions