Adenosine deaminase (CECR1, ADA2) degrades extracellular adenosine (Ade-Rib), a signaling molecule that controls a variety of cellular responses (Zavialov & Engstrom 2005). Extracellular adenosine can bind and activate four adenosine receptors (ADRs), triggering multiple intracellular processes leading to either cell activation or in suppression of cell function and cell death. ADA2 (and ADA1) decrease the local concentration of adenosine by catalysing the deamination of adenosine to inosine (Ino). ADA2 is dimeric, binding one Zn2+ ion per subunit (Zavialov et al. 2010).