title: Molecular symmetry as an aid to geometry determination in ligand protein complexes.
abstract: Dipole-dipole couplings between pairs of spin 12 nuclei, which can be measured from NMR spectra in field-ordered media, offer useful constraints on the orientation of various fragments in molecular systems. However, the orientation of fragments relative to a molecule fixed reference frame is often key to complete structure determination. Here, we demonstrate that the symmetry properties of molecular complexes can aid in the definition of a reference frame. It is shown that a threefold rotational symmetry axis dictates the direction and symmetry of the experimentally determined order tensor for alpha-methyl-mannose in fast exchange among the three symmetry-related binding sites of mannose binding protein. This approach facilitates studies of the geometry of the ligand in the protein-ligand complex and also may provide a novel route to structure determination of a homomultimeric protein.
authors.affiliation: Complex Carbohydrate Research Center, University of Georgia, Athens, Georgia 30602, USA.
authors.forename: H M
authors.initials: HM
authors.lastname: Al-Hashimi
authors.forename: P J
authors.initials: PJ
authors.lastname: Bolon
authors.forename: J H
authors.initials: JH
authors.lastname: Prestegard
mesh_terms: D002352:Carrier Proteins / Q000737:chemistry*; D037222:Collectins; D037102:Lectins / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008766:Methylmannosides / Q000737:chemistry*; D011485:Protein Binding
chemical_list: D002352:Carrier Proteins; D037222:Collectins; D037102:Lectins; D008766:Methylmannosides; C008466:methylmannoside