Kinetic studies on adenosine deaminase. Influence of H+ concentration on enzymate activity and its inhibition by dipyridamole

Abstract

It has been studied in vitro the inhibition of the adenosin-desaminase by the action of DPD at different values of pH. The enzimatic inhibition after 45 minutes of incu­ bation at 37° of the enzime and the inhibitor is 15, 25, 26, 28, 76 and 78 %, for pH values of 8, 7.4, 6.6, 6.2, 5.6 and 5.2, respectively. When the pH of the incubation mix­ ture is modified from 7 to 5.6, the value of Ki obtained in a previous report (12), is considerabily descended from 0.16 mM to 0.025 mM. We advance the interpretation of the dependence of this enzymatic inhibition by the DPD, related to the pH, to certains modifications of the electronic structure of the DPD what are been resarched now.