Molecular Symmetry as an Aid to Geometry Determination in Ligand Protein Complexes

✍ Scribed by H.M Al-Hashimi; P.J Bolon; J.H Prestegard

• Book ID: 102600302
• Publisher: Elsevier Science
• Year: 2000
• Tongue: English
• Weight: 76 KB
• Volume: 142
• Category: Article
• ISSN: 1090-7807
• DOI: 10.1006/jmre.1999.1937

✦ Synopsis

Dipole-dipole couplings between pairs of spin 1

2 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 ␣-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.