 However, a computerized docking model of the inhibitor EHNA and the substrates cAMP and cGMP bound in the catalytic site have been made.The docking model of EHNA showed that the mutations of the amino acids Asp811 to Ala (Asp811Ala) and Ile826 to Val (Ile826Val) at the active site, where the only amino acid substitutions that significantly affected the inhibition by EHNA.The Asp811 mutation to alanine increased IC50 value for EHNA 6-fold and the Ile826 mutation to valine leads to a 7-fold increased IC50 value for EHNA compared to wild type PDE2A.