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Ti (IV) se une a la transferrina sérica humana más fuertemente que el Fe (III)
Arthur D Tinoco1, Ann M Valentine
1Department of Chemistry, Yale University, P.O. Box 208107, New Haven, Connecticut 06520-8107, USA.
Journal of the American Chemical Society
|August 11, 2005
Resumen
El titanio (IV) se une a la transferrina sérica humana con mayor afinidad que el hierro (III), lo que afecta a la eficacia de los fármacos de titanio y a la unión de iones séricos. Este estudio cuantifica las interacciones titanio-transferrina, revelando diferencias significativas en la fuerza de unión.
Área de la Ciencia:
- La bioquímica es la bioquímica.
- La metalómica es la metalología.
- Química biofísica y bioquímica.
Sus antecedentes:
- La transferrina sérica humana (hST) es una proteína transportadora de hierro clave.
- La comprensión de las interacciones de iones metálicos con hST es crucial para la farmacología y la toxicología.
- Los compuestos de titanio (IV) se utilizan en medicamentos contra el cáncer, implantes y reactivos de imagen.
Objetivo del estudio:
- Para cuantificar la afinidad de unión del titanio (IV) a la transferrina sérica humana.
- Para comparar la unión del titanio (IV) a la transferrina con la del hierro (III).
- Para aclarar las contribuciones termodinámicas y entrópicas a la unión del titanio.
Principales métodos:
- La cinética UV/vis de los rayos UV.
- Calorimetría de titulación isotérmica (ITC, por sus siglas en inglés)
- Estudio de la unión del complejo de citrato de Ti (IV) al hST en condiciones fisiológicas de pH y de amortiguador.
Principales resultados:
- El titanio (IV) exhibe una afinidad de unión significativamente mayor a la transferrina (log K = 26.8 y 25.7) en comparación con el hierro (III) (log K = 22.5 y 21.4).
- La afinidad de unión se correlaciona con la acidez de Lewis del ion metálico.
- El titanio (IV) se une preferentemente a un sitio de transferrina sobre el otro, influenciado tanto por la entalpía como por la entropía.
Conclusiones:
- La interacción del titanio (IV) con la transferrina es más fuerte que la del hierro (III), lo que desafía las suposiciones anteriores para los iones metálicos.
- Los hallazgos tienen implicaciones para los mecanismos de medicamentos anticancerígenos basados en titanio y el comportamiento de los iones de titanio en los sistemas biológicos.
- La transferrina juega un papel importante en el destino biológico y la actividad del titanio (IV).
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