Binding properties of adenosine deaminase interacted with theophylline.
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.
Institute of Biochemistry and Biophysics, University of Tehran, Tehran, Iran. saboury@chamran.ut.ac.ir
Ali Akbar
AA
Saboury
Soghra
S
Bagheri
Ghasem
G
Ataie
Masoud
M
Amanlou
Ali Akbar
AA
Moosavi-Movahedi
Gholam Hossein
GH
Hakimelahi
Gloria
G
Cristalli
Saeid
S
Namaki
D000243:Adenosine Deaminase / Q000737:chemistry*; D001993:Bronchodilator Agents / Q000737:chemistry*; D002151:Calorimetry; D008024:Ligands; D010726:Phosphodiesterase Inhibitors / Q000737:chemistry*; D011485:Protein Binding; D013806:Theophylline / Q000737:chemistry*; D013816:Thermodynamics; D017186:Titrimetry
D001993:Bronchodilator Agents; D008024:Ligands; D010726:Phosphodiesterase Inhibitors; D013806:Theophylline; D000243:Adenosine Deaminase