Purification and molecular docking study of a novel angiotensin-I converting enzyme (ACE) inhibitory peptide from alcalase hydrolysate of ultrasonic-pretreated silkworm pupa (Bombyx mori) protein

• Ultrasonic pretreatment was used to produce ACE inhibitory peptide from silkworm pupa protein.
• ACE inhibitory peptide was identified as Lys-His-Val.
• The peptide was stable against gastrointestinal proteases.
• The peptide could effectively interact with the active site of ACE.

Silkworm pupa (Bombyx mori) protein (SPP) was treated by ultrasound, and then was hydrolyzed using alcalase. The hydrolysate with the highest ACE inhibitory activity was obtained at hydrolysis of 50 min when SPP was treated at power of 410 W/100 ml for 32 min. The hydrolysate was fractionated by ultrafiltration, and peptide with the highest ACE inhibitory activity was purified from <5 kDa fraction using gel filtration and RP-HPLC. A novel peptide was identified as Lys-His-Val (IC50 = 12.82 μM), and it was stable against the gastrointestinal proteases. The molecular docking study revealed that ACE inhibitory activity of the tripeptide was mainly attributed to the hydrogen bond interactions and Zn(II) interaction between the tripeptide and ACE. These results suggest that the tripeptide is a potential natural ACE inhibitor that can be used as drug or functional food ingredient.

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