a product inhibition study on adenosine deminase dy spectroscopy and calorimetry

Abstract

Kinetic and thermodynamic studies have been made on<br><br>the effect of the inosine product on the activity of<br><br>adenosine deaminase in a 50 mM sodium phosphate<br><br>buffer, pH 7.5, at 27oC using UV spectrophotometry and<br><br>isothermal titration calorimetry (ITC). A competitive<br><br>inhibition was observed for inosine as a product of the<br><br>enzymatic reaction. A graphical-fitting method was used<br><br>for determination of the binding constant and enthalpy of<br><br>inhibitor binding by using isothermal titration<br><br>microcalorimetry data. The dissociation-binding constant<br><br>is equal to 140 µM by the microcalorimetry method, which<br><br>agrees well with the value of 143 µM for the inhibition<br><br>constant that was obtained from the spectroscopy method.