title: SOMO (SOlution MOdeler) differences between X-Ray- and NMR-derived bead models suggest a role for side chain flexibility in protein hydrodynamics.
abstract: Reduced numbers of frictional/scattering centers are essential for tractable hydrodynamic and small-angle scattering data modeling. We present a method for generating medium-resolution models from the atomic coordinates of proteins, basically by using two nonoverlapping spheres of differing radii per residue. The computed rigid-body hydrodynamic parameters of BPTI, RNase A, and lysozyme models were compared with a large database of critically assessed experimental values. Overall, very good results were obtained, but significant discrepancies between X-ray- and NMR-derived models were found. Interestingly, they could be accounted for by properly considering the extent to which highly mobile surface side chains differently affect translational/rotational properties. Models of larger structures, such as fibrinogen fragment D and citrate synthase, also produced consistent results. Foremost among this method's potential applications is the overall conformation and dynamics of modular/multidomain proteins and of supramolecular complexes. The possibility of merging data from high- and low-resolution structures greatly expands its scope.
authors.affiliation: Division of Infection & Immunity, Institute of Biomedical & Life Sciences, University of Glasgow, Glasgow, G12 8QQ, United Kingdom.
authors.forename: Nithin
authors.initials: N
authors.lastname: Rai
authors.forename: Marcelo
authors.initials: M
authors.lastname: Nöllmann
authors.forename: Bruno
authors.initials: B
authors.lastname: Spotorno
authors.forename: Giovanni
authors.initials: G
authors.lastname: Tassara
authors.forename: Olwyn
authors.initials: O
authors.lastname: Byron
authors.forename: Mattia
authors.initials: M
authors.lastname: Rocco
mesh_terms: D000465:Algorithms; D018360:Crystallography, X-Ray; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D011487:Protein Conformation; D011506:Proteins / Q000737:chemistry*
chemical_list: D011506:Proteins