Abstract:

Two angiotensin-converting enzyme inhibitory peptides VPP and IPP were purified from the sour milk fermented with Lactobacillus helveticus JCM1004 and Lactobacillus casei subsp. casei ATCC393 by using four-step reverse-phase HPLC. VPP and IPP had 50% inhibition of ACE (IC50) of 8.89μmol/L and 5.17μmol/L, respectively. According to their amino acid sequence, the molecular structure of VPP and IPP were simulated, and the molecular mechanism for the function position, type and energy of the interaction between ACE inhibitory peptides and ACE were investigated by the flexible molecule docking technology. It was shown from the theoretical calculation that the three hydrogen bonds existed between the bioactive peptides poses of VPP and IPP. Hydrophobic and hydrophilic interactions also existed between residues at the ACE active site and the peptide poses. The binding between IPP and ACE was more stable than VPP with ACE. This is in good agreement with the experimental result that the IC50 value of IPP is lower than that of VPP.

Key words: VPP, IPP, ACE inhibitory peptides, molecular modeling