The binding of Mn2+ ions to ATP molecules has been studied by means of the fine-structure analysis of X-ray absorption spectra (EXAFS and XANES) at the K-edge of Mn using the synchrotron, radiation facility PULS in Frascati. The results obtained in both freeze-dried and liquid samples of aqueous solutions at room temperature of the Mn-ATP complex under diffrent values of pH and Mn:ATP ratio are reported and discussed. The Mn2+ ion appears to be octahedrally coordinated, the phosphate oxygen atoms being in the first co-ordination shell. Values of (2.15±0.05) Å and (3.4±0.05) Å, respectively, have been found for Mn-O and Mn-P distances. Theoretical considerations together with experimental results do not support the existence of a direct binding of the Mn to the N(7) atom of the adenine ring. The coordination numbers for the first and second shell are consistent with the formation of a Mn(ATP)2 complex in solution at pH=9 and Mn: ATP=1:10, while a Mn-ATP 1:1 complex is found at lower pH and higher Mn: ATP ratios.

EXAFS and XANES Structure determination of Mn2+ binding in ATP complexes

PALLADINO, Libero
1983-01-01

Abstract

The binding of Mn2+ ions to ATP molecules has been studied by means of the fine-structure analysis of X-ray absorption spectra (EXAFS and XANES) at the K-edge of Mn using the synchrotron, radiation facility PULS in Frascati. The results obtained in both freeze-dried and liquid samples of aqueous solutions at room temperature of the Mn-ATP complex under diffrent values of pH and Mn:ATP ratio are reported and discussed. The Mn2+ ion appears to be octahedrally coordinated, the phosphate oxygen atoms being in the first co-ordination shell. Values of (2.15±0.05) Å and (3.4±0.05) Å, respectively, have been found for Mn-O and Mn-P distances. Theoretical considerations together with experimental results do not support the existence of a direct binding of the Mn to the N(7) atom of the adenine ring. The coordination numbers for the first and second shell are consistent with the formation of a Mn(ATP)2 complex in solution at pH=9 and Mn: ATP=1:10, while a Mn-ATP 1:1 complex is found at lower pH and higher Mn: ATP ratios.
File in questo prodotto:
Non ci sono file associati a questo prodotto.
Pubblicazioni consigliate

I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.

Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11697/18003
Citazioni
  • ???jsp.display-item.citation.pmc??? ND
  • Scopus 5
  • ???jsp.display-item.citation.isi??? ND
social impact