The hypertension is one of the highest risk factors for stroke, myocardial infarction, vascular disease and chronic kidney disease. Angiotensin converting enzyme (ACE) has an important role in the physiological regulation of cardiovascular system. ACE inhibition is a key purpose for hypertension treatment. In this study, two peptides named HL-7 with the sequence of YLYELAR (MW: 927.07 Da) and HL-10 with the sequence of AFPYYGHHLG (MW: 1161.28 Da) were identified from scorpion venom of H. lepturus. The inhibitory activity of HL-7 and HL-10 was examined on rabbit ACE. The inhibition mechanisms were assayed by kinetic and docking studies. The IC50 values for ACE inhibition of HL-7 and HL-10 were 9.37 mM and 17.22 mM, respectively. Lineweaver-Burk plots showed that two peptides inhibited rabbit ACE with competitive manner. The molecular docking conformed experimental results and showed that the two peptides interacted with N-domain and C-domain active sites. Also, docking study revealed that the two peptides can form hydrogen and hydrophobic bonds at their binding sites. Both peptides had higher affinity to N-domain. Our results showed that HL-7 exhibited more strong interactions with amino acids at active site. It seems that HL-10 peptide could occupy more space, thereby inhibiting the substrate entrance to active site.

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