title: Design, synthesis, and evaluation of a lanthanide chelating protein probe: CLaNP-5 yields predictable paramagnetic effects independent of environment.
abstract: Immobilized lanthanide ions offer the opportunity to refine structures of proteins and the complexes they form by using restraints obtained from paramagnetic NMR experiments. We report the design, synthesis, and spectroscopic evaluation of the lanthanide chelator, Caged Lanthanide NMR Probe 5 (CLaNP-5) readily attachable to a protein surface via two cysteine residues. The probe causes tunable pseudocontact shifts, alignment, paramagnetic relaxation enhancement, and luminescence, by chelating it to the appropriate lanthanide ion. The observation of single shifts and the finding that the magnetic susceptibility tensors obtained from shifts and alignment analyses are highly similar strongly indicate that the probe is rigid with respect to the protein backbone. By placing the probe at various positions on a model protein it is demonstrated that the size and orientation of the magnetic susceptibility tensor of the probe are independent of the local protein environment. Consequently, the effects of the probe are readily predictable using a protein structure only. These findings designate CLaNP-5 as a protein probe to deliver unambiguous high quality structural restraints in studies on protein-protein and protein-ligand interactions.
authors.affiliation: Leiden Institute of Chemistry, Gorlaeus Laboratories, Leiden University, Post Office Box 9502, 2300 RA Leiden, The Netherlands.
authors.forename: Peter H J
authors.initials: PH
authors.lastname: Keizers
authors.forename: Athanasios
authors.initials: A
authors.lastname: Saragliadis
authors.forename: Yoshitaka
authors.initials: Y
authors.lastname: Hiruma
authors.forename: Mark
authors.initials: M
authors.lastname: Overhand
authors.forename: Marcellus
authors.initials: M
authors.lastname: Ubbink
mesh_terms: D002614:Chelating Agents / Q000138:chemical synthesis / Q000737:chemistry*; D028581:Lanthanoid Series Elements / Q000737:chemistry*; D008024:Ligands; D008280:Magnetics; D008958:Models, Molecular; D019906:Nuclear Magnetic Resonance, Biomolecular / Q000379:methods*; D009942:Organometallic Compounds / Q000138:chemical synthesis / Q000737:chemistry*; D011487:Protein Conformation; D011506:Proteins / Q000032:analysis* / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D002614:Chelating Agents; D028581:Lanthanoid Series Elements; D008024:Ligands; D009942:Organometallic Compounds; D011506:Proteins