Binding Properties of Adenosine Deaminase Interacted with Theophylline

Ali Akbar Saboury; Soghra Bagheri; Ghasem Ataie; Masoud Amanlou; Ali Akbar Moosavi-Movahedi; Gholam Hossein Hakimelahi; Gloria Cristalli; Saeid Namaki

doi:10.1248/cpb.52.1179

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Binding Properties of Adenosine Deaminase Interacted with Theophylline

Ali Akbar Saboury, Soghra Bagheri, Ghasem Ataie, Masoud Amanlou, Ali Akbar Moosavi-Movahedi, Gholam Hossein Hakimelahi, Gloria Cristalli, Saeid Namaki

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Keywords: adenosine deaminase, theophylline, cooperativity, isothermal titration calorimetry, calorimetric method

JOURNAL FREE ACCESS

2004 Volume 52 Issue 10 Pages 1179-1182

DOI https://doi.org/10.1248/cpb.52.1179

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Abstract

Thermodynamic studies were carried out to evaluate the binding of theophylline on adenosine deaminase (ADA) in 50 mM sodium phosphate buffer pH 7.5, at 300 K, using isothermal titration calorimetry (ITC). A simple method for determination of binding isotherm in the drug–ADA interaction was applied using ITC data. ADA has two binding sites for theophylline, which show positive cooperativity in its sites. The intrinsic association equilibrium constants are 6 and 52 mM⁻¹ in the first and second binding sites, respectively. Hence, occupation of the first site has produced an appreciable enhancement by 8.7 of the binding affinity of the second site. The molar enthalpies of binding are −12.2 and −14.9 kJ/mol in the first and second binding sites, respectively.

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