Inhibitory Mechanism And Structure Activity Relationship Of ACE Inhibitory Peptides From Silkworm Pupa Protein

This paper focused on the inhibition mechanism of the ACE inhibitory peptide screened from silkworm pupae and the works included three parts:(1)The physicochemical property and the inhibition types of ACE inhibitory peptide(GAMVVH)from silkworm pupa protein was investigated,meanwhile,the the molecular binding sites and molecular dynamics were investigated by molecular docking and dynamics simulation.(2)the inhibitory mechanism of ACE inhibitory peptide(NR,YLR and NR/YLR)were investigated by experiment and molecular docking.(3)The foodborne ACE inhibitory peptides with different chain length was analyzed using CoMFA and CoMSIA analysis method,to build the 3D-QSAR.The main research results as follows:(1)The GAMVVH peptide had a comparatively high ACE inhibitory activity(IC50= 19.3±0.21 ?M)with good thermal and anti-digestive stabilities.Lineweaver-Burk plots indicated that the peptide was a competitive inhibitor,Ki=0.506×10-5M.Moreover,molecular docking and dynamics simulation showed that GAMVVH formed very strong hydrogen bonds with S1(Ala354)and S2(Gln281,His353 and Lys511)pockets of ACE.Besides,the GAMVVH was able to established coordination with Zn(II)of ACE(bond length =2.5 A)and distorted the original Zn(II)tetrahedral structure in ACE.(2)The inhibitory activity of peptides NR and YLR was about 17.8 ?M(NR)and 15.1 ?M(YLR),respectively.Lineweaver-Burk inhibition kinetics curves showed that NR and YLR all were a non-competitive inhibitor,the Ki were 2.11×10-5 M(NR)and 1.87×10-5 M(YLR),respectively.It indicated that the binding energy of ACE with YLR was bigger than ACE with NR.Molecular docking showed that NR formed hydrogen bonds with the polypeptide Ala354(2.0 A),Glu384(1.9 A),Asp415(2.0 A),Lys511(2.2 A)and Tyr520(2.0 A);YLR formed hydrogen bonds with the polypeptide Gln281(2.1 A),His353(2.3 A),Ala354(2.3 A),Glu384(2.3 A),Asp415(2.1 A)and Lys511(2.2 A)of ACE.In addition,we found that the conformation of the peptide NR and peptide YLR in the ACE was partially overlapped.(3)The ACE inhibitory peptides from food was analysised by using CoMFA and CoMSIA analysis method,the ACE inhibitory peptides was divided into three data sets by peptides length and there were 102 different combinations of power field analyzed in three data sets,finally the 3D-QSAR force field for each data sets was determined(di-pepitdes:CoMFA Steric;tri-pepitdes:CoMSIA Steric&Electrostatic&Acceptor;tetra-,penta-and hexa-pepitdes:CoMSIA Steric).The results showed that the model had high reliability and accuracy.