Study On The Structure-Activity Relationship Of ACE Inhibitory Peptides YS And INN

Hypertension is one of the most common chronic diseases in the world,and it is also the main risk factor of cardiovascular and cerebrovascular diseases.Angiotensin-converting enzyme is a zinc-containing dipeptide carboxypeptidase,which plays an important role in the blood pressure regulation system.ACE inhibitory peptides is a kind of antihypertensive peptides derived from food.These peptides can decrease blood pressure by inhibiting the activity of ACE.In this paper,the characters of the synthesized dipeptide YS and decapeptide INNQFLPYPY?named INN?,including in vitro ACE inhibitory activities,stability,antihypertensive activity on SHR,inhibition type and molecular dynamics simulation analysis,were studied.The results are as follows:?1?The inhibitory activities of ACE inhibitory peptides YS and INNQFLPYPY were measured by UV spectrophotometry.The relationship between the ACE inhibition rate and the concentration of YS and INNQFLPYPY was found by fitting equation,and their IC₅₀0 values were calculated.The results showed that the IC₅₀0 value of ys was 22.62?g/m L and the IC₅₀0 value of INNQFLPYPY was 210.996?g/mL.?2?The ACE inhibitory peptides YS and INNQFLPYPY were stable after being incubated at 4?,20?,37?,42?and 65?for 1 h.Under the condition of pH1.0,pH3.0,pH5.0,pH7.0,pH9.0 for 2 h and 3 h,YS was more stable in acidic solution than that in weak alkali solution,and INNQFLPYPY was more stable in neutral and weak alkaline solution than in acidic solution,respectively.In vitro digestion experiment shows that both YS and INNQFLPYPY were stable against digest of pepsin and trypsin.?3?The enzyme inhibition types of ACE inhibitory peptides YS and INNQFLPYPY were studied with inhibition enzymatic hydrolysis kinetics.According to the Lineweaver-Burk equation of YS and INNQFLPYPY interaction with ACE,both YS and INNQFLPYPY were competitive inhibition types.?4?The antihypertensive effects of ACE inhibitory peptides YS and INNQFLPYPY in vivo were studied by oral administration of spontaneous hypertensive rats?SHRs?and Wistar rats.The results showed that the blood pressure of SHRs could be significantly decreased by oral administrated a certain dosage range of INNQFLPYPY and YS.These ACE inhibitory peptides had no effect on the blood pressure of Wistar rats.The results of single oral administration YS showed that the blood pressure of SHRs in each dose group decreased by 15 mg/?kg.BW?at about 4 h,and the blood pressure of SHR decreased 41.81±4.46 mmHg in each dose group.The results of single oral administration INNQFLPYPY showed that the blood pressure of SHRs in each dose group decreased by 15 mg/?kg.BW?at about 4 h,and the blood pressure of SHR decreased 34.26±4.13 mmHg in each dose group.Compared with Captopril,both of the two peptides had similar effect of decreasing blood pressure.The blood pressure of SHRs decreased continuously within 7 hours after continuous oral administration of YS.The maximum blood pressure reduction was-52.86±4.19 mmHg at 7h after oral administration.The blood pressure of SHRs increased after 8¹2 h,which increased to-26±4.74 mmHg at 12 h.The blood pressure of SHRs decreased continuously within 7 hours after continuous INNQFLPYPY administration.The maximum blood pressure reduction was-41.16±4.79 mmHg at 8 h after oral administration.The blood pressure decreased to-19.08±2.4 mmHg at 12 h after oral administration.?5?Molecular dynamics simulation analysis shows that van der Waals force and hydrostatic force play an important role in the binding process of ACE-YS and ACE-INNQFLPYPY.In the process of INNQFLPYPY combining with ACE,van der Waals force is the major contribution.INNQFLPYPY interacts with the amino acid residues His365,Lys522 and His524 in the middle of the ACE pocket and amino acid residues Tyr220,Tyr231,Gly127,Arg415,Ala416,Asn417 in the right pocket which form a large number of hydrogen bonds.In the process of YS combining with ACE,electrostatic force is the major contribution,and van der Waals force is relatively weak.YS interacts with the amino acid residues Asp426,Gn293,Glu396 and Lys522 in the middle pocket of ACE which form hydrogen bonds.