Characterization of ATP complexes with lanthanide (III) ions

Area of Science:

• Biochemistry
• Inorganic Chemistry
• Spectroscopy

Background:

• Adenosine triphosphate (ATP) is a vital molecule in cellular energy transfer.
• Lanthanide ions (Ln(III)) are used as probes in biological systems due to their unique spectroscopic properties.
• Understanding the interaction between ATP and metal ions is crucial for various biological processes.

Purpose of the Study:

• To investigate the stoichiometry and properties of ATP-lanthanide(III) complexes.
• To determine the number of water molecules coordinated to lanthanide ions in these complexes.
• To study the dynamic properties and exchange mechanisms within the ATP-lanthanide complexes.

Main Methods:

• Spectroscopic techniques, including luminescence lifetime measurements and 31P NMR relaxation.
• Field-dependent water proton relaxation studies.
• Metal ion luminescence lifetime measurements.

Main Results:

• The ATP2-lanthanide(III) complex is predominant at millimolar ATP levels.
• A dissociation constant (Kd) of approximately 300 microM was found for the Eu(III) 1:1 complex.
• The metal ion hydration number was determined to be approximately 2 for the 2:1 complex and 4 for the 1:1 complex.
• Dynamic properties, including rotational correlation times and ATP exchange, were characterized.

Conclusions:

• The formation of 2:1 ATP-lanthanide complexes is favored at millimolar ATP concentrations.
• The coordination and hydration numbers provide insights into the structural characteristics of these complexes.
• Dynamic studies elucidate the stability and exchange processes within the ATP-lanthanide systems.