title: Order-parameter tensor description of HPr in a medium of oriented bicelles.
abstract: Residual dipolar couplings between 15N and 1H nuclear spins in HPr were used to determine the protein's orientation in a medium of bicelles, oriented by a magnetic field. In the case of wild-type HPr the protein's non-spherical shape can explain its orientation in this medium. In the case of the F48W mutant it was found that at least one other mechanism contributes to the observed orientation of the protein, to a degree that depends on the concentration of phosphate ions in the medium. We propose that the F48W mutant has a weak affinity towards the bicelle-surfaces that decreases with increasing phosphate concentrations. We used an order-parameter description to analyse this situation and to determine the axis of main order and the sign of the order parameter pertaining to this additional orientation mechanism.
authors.affiliation: Biophysical Chemistry Department, Groningen Institute of Biomolecular Sciences and Biotechnology, University of Groningen, The Netherlands.
authors.forename: Franciska
authors.initials: F
authors.lastname: van Lune
authors.forename: Linda
authors.initials: L
authors.lastname: Manning
authors.forename: Klaas
authors.initials: K
authors.lastname: Dijkstra
authors.forename: Herman J C
authors.initials: HJ
authors.lastname: Berendsen
authors.forename: Ruud M
authors.initials: RM
authors.lastname: Scheek
mesh_terms: D016880:Anisotropy; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008051:Lipid Bilayers / Q000737:chemistry* / Q000378:metabolism; D008280:Magnetics; D008956:Models, Chemical; D008958:Models, Molecular; D020125:Mutation, Missense; D019906:Nuclear Magnetic Resonance, Biomolecular; D010713:Phosphatidylcholines / Q000737:chemistry / Q000378:metabolism; D010714:Phosphatidylethanolamines / Q000737:chemistry / Q000378:metabolism; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011092:Polyethylene Glycols / Q000737:chemistry / Q000378:metabolism
chemical_list: D001426:Bacterial Proteins; D008051:Lipid Bilayers; D010713:Phosphatidylcholines; D010714:Phosphatidylethanolamines; C067972:dioleoyl-N-(monomethoxypolyethylene glycol succinyl)phosphatidylethanolamine; D011092:Polyethylene Glycols; D010731:Phosphoenolpyruvate Sugar Phosphotransferase System; C030182:phosphocarrier protein HPr