The comparative analysis of oxytocin and angiotensin IV tetrahedral intermediates reveals both similarities and significant differences in their interactions with the enzyme's active site. While both peptides form analogous hydrogen bonds with the backbones of Gly428 and Ala429, as well as the sidechain of Glu431 from the GAMEN loop, notable distinctions were observed in the frequency and nature of these interactions. A quantitative analysis revealed a 17% reduction in hydrogen bonding frequency between the NH of the scissile peptide and Ala429 in the angiotensin IV complex. Additionally, a markedly lower occurrence of hydrogen bonding with Gly428 was observed in the angiotensin IV complex compared to oxytocin (Figure ).