Fluorescing Isofunctional Ribonucleosides: Assessing Adenosine Deaminase Activity and Inhibition

The enzymatic conversion of isothiazolo[4,3-d]pyrimidine-based adenosine ( tz A) and 2-aminoadenosine ( tz 2-AA) analogues to the corresponding isothiazolo[4,3-d]pyrimidine-based inosine ( tz I) and guanosine ( tz G) derivatives is evaluated and compared to the conversion of native adenosine to inosine. Henri–Michaelis–Menten analyses provides the foundation for a high-throughput screening assay, and the efficacy of the assay is showcased by fluorescence-based analysis of tz A conversion to tz I in the presence of known and newly synthesized inhibitors.