A pH-sensitive, colorful, lanthanide-chelating paramagnetic NMR probe.
J Am Chem Soc
; 134(41): 17306-13, 2012 Oct 17.
Article
em En
| MEDLINE
| ID: mdl-22994925
ABSTRACT
Paramagnetic lanthanides ions are broadly used in NMR spectroscopy. The effects of unpaired electrons on NMR spectral parameters provide a powerful tool for the characterization of macromolecular structures and dynamics. Here, a new lanthanide-chelating NMR probe, Caged Lanthanide NMR Probe-7 (CLaNP-7), is presented. It can be attached to protein surfaces via two disulfide bridges, yielding a probe that is rigid relative to the protein backbone. CLaNP-7 extends the application range of available probes. It has a yellow color, which is helpful for sample preparation. Its effects are comparable to those of CLaNP-5, but its charge is two units lower (+1) than that of CLaNP-5 (+3), reducing the change in surface potential after probe attachment. It also has a different magnetic susceptibility tensor, so by using both tags, two sets of structural restraints can be obtained per engineered cysteine pair. Moreover, it was found that the orientation of the magnetic susceptibility tensor is pH dependent (pK(a) ≈ 7) when a histidine residue is located in the neighborhood of the probe attachment site. The results show that the His imidazole group interacts with the CLaNP-7 tag. It is proposed that the histidine residue forms a hydrogen bond to a water/hydroxyl molecule that occupies the ninth coordination position on the lanthanide, thus breaking the two-fold symmetry of the CLaNP tag in a pH-dependent way.
Texto completo:
1
Coleções:
01-internacional
Base de dados:
MEDLINE
Assunto principal:
Quelantes
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Ressonância Magnética Nuclear Biomolecular
/
Elementos da Série dos Lantanídeos
/
Corantes Fluorescentes
Tipo de estudo:
Diagnostic_studies
Idioma:
En
Revista:
J Am Chem Soc
Ano de publicação:
2012
Tipo de documento:
Article
País de afiliação:
Holanda