In the current work using mass-spectrometry and molecular modelling we have tested a set of synthetic peptides (with free, as well as partially or fully protected termini) corresponding to Aβ MBD and ratAβ MBD (Table 1, Supplementary Fig. S1) as substrates for N- and C- domains of ACE to get more insights into the role of the interactions between ACE and Aβ in AD pathogenesis. The gene discussed is ACE; the disease is Alzheimer disease.