Graphitized Porous Carbon for Rapid Screening of Angiotensin-Converting Enzyme Inhibitory Peptide GAMVVH from Silkworm Pupa Protein and Molecular Insight into Inhibition Mechanism.

A novel hydrophobic hexapeptide with high angiotensin-converting enzyme (ACE) inhibitory activity was screened from silkworm pupa protein (SPP) hydrolysate via graphitized porous carbon and reverse-phase high-performance liquid chromatography methods. Graphitized porous carbon derived from dopamine, possessing high surface area and high graphitic carbon, was used to rapidly screen and enrich hydrophobic peptides from SPP hydrolysate. The ACE inhibition pattern and mechanism of the purified peptide were also systematically studied by the classic Lineweaver-Burk model and by molecular docking/dynamic simulation. The novel hydrophobic hexapeptide was identified as Gly-Ala-Met-Val-Val-His (GAMVVH, IC50 = 19.39 ± 0.21 µM) with good thermal/antidigestive stabilities. Lineweaver-Burk plots revealed that GAMVVH behaved as a competitive ACE inhibitor. It formed hydrogen bonds with S1 and S2 pockets of ACE and established competitive coordination with Zn(II) of ACE. The synergy of hydrogen bonds with active pockets and Zn(II) coordination efficiently changed the three-dimensional structure of ACE and thus inhibited bioactivity of ACE.