Characterizing the magnetic susceptibility tensor of lanthanide-containing polymethylated-DOTA complexes.
J Biomol NMR
; 66(2): 125-139, 2016 10.
Article
en En
| MEDLINE
| ID: mdl-27659040
ABSTRACT
Lanthanide complexes based on the DOTA (1,4,7,10-tetraazacyclododecane-1,4,7,10-tetraacetic acid) cage are commonly used as phase contrast agents in magnetic resonance imaging, but can also be utilized in structural NMR applications due to their ability to induce either paramagnetic relaxation enhancement or a pseudocontact shift (PCS) depending on the choice of the lanthanide. The size and sign of the PCS for any given atom is determined by its coordinates relative to the metal center, and the characteristics of the lanthanide's magnetic susceptibility tensor. Using a polymethylated DOTA tag (Ln-M8-SPy) conjugated to ubiquitin, we calculated the position of the metal center and characterized the susceptibility tensor for a number of lanthanides (dysprosium, thulium, and ytterbium) under a range of pH and temperature conditions. We found that there was a difference in temperature sensitivity for each of the complexes studied, which depended on the size of the lanthanide ion as well as the isomeric state of the cage. Using 17O-NMR, we confirmed that the temperature sensitivity of the compounds was enhanced by the presence of an apically bound water molecule. Since amide-containing lanthanide complexes are known to be pH sensitive and can be used as probes of physiological pH, we also investigated the effect of pH on the Ln-M8-SPy susceptibility tensor, but we found that the changes in this pH range (5.0-7.4) were not significant.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Espectroscopía de Resonancia Magnética
/
Elementos de la Serie de los Lantanoides
/
Compuestos Heterocíclicos con 1 Anillo
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
J Biomol NMR
Asunto de la revista:
BIOLOGIA MOLECULAR
/
DIAGNOSTICO POR IMAGEM
/
MEDICINA NUCLEAR
Año:
2016
Tipo del documento:
Article
País de afiliación:
Estados Unidos