2ADA: Adenosine Deaminase

The structure of Adenosine Deaminase (ADA) to the right is shown complexed with a transition state analog, 6-Hydroxyl-1,6-Dihydropurine Ribonucleoside.

On this structure, identify the following properties:

  • Two barrel structures

  • Connecting loops

  • Active Site

  • Bound Purine ribonucleoside

  • Zn (II) ion

  • Some ligands that might be associated with this ion




Defects of ADA activity result in "Severe Combined Immunodeficiency Disease" (SCID) because of the resultant destruction of lymphocytes. We will describe the mechanism of this effect later on, when we look at the formation of deoxynucleotides