title: Lanthanide-binding peptides for NMR measurements of residual dipolar couplings and paramagnetic effects from multiple angles.
abstract: Lanthanide-binding peptide tags (LBTs) containing a single cysteine residue can be attached to proteins via a disulfide bond, presenting a flexible means of tagging proteins site-specifically with a lanthanide ion. Here we show that cysteine residues placed in different positions of the LBT can be used to expose the protein to different orientations of the magnetic susceptibility anisotropy (delta chi) tensor and to generate different molecular alignments in a magnetic field. Delta chi tensors determined by nuclear magnetic resonance (NMR) spectroscopy for LBT complexes with Yb3+, Tm3+, and Er3+ suggest a rational way of producing alignment tensors with different orientations. In addition, knowledge of the delta chi tensor of LBT allows modeling of the protein-LBT structures. Despite evidence for residual mobility of the LBTs with respect to the protein, the pseudocontact shifts and residual dipolar couplings displayed by proteins disulfide-bonded to LBTs are greater than those achievable with most other lanthanide binding tags.
authors.affiliation: Research School of Chemistry, Australian National University, Canberra ACT 0200, Australia.
authors.forename: Xun-Cheng
authors.initials: XC
authors.lastname: Su
authors.forename: Kerry
authors.initials: K
authors.lastname: McAndrew
authors.forename: Thomas
authors.initials: T
authors.lastname: Huber
authors.forename: Gottfried
authors.initials: G
authors.lastname: Otting
mesh_terms: D000595:Amino Acid Sequence; D028581:Lanthanoid Series Elements / Q000737:chemistry* / Q000378:metabolism*; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000737:chemistry* / Q000378:metabolism*; D017434:Protein Structure, Tertiary
chemical_list: D028581:Lanthanoid Series Elements; D010455:Peptides