Study On Preparation Of ACE Inhibitory Peptide From The Oyster (Ostrea Tailienwhanensis)

1.In this paper,the proteins composition in oyster protein was compared,and the extraction process of oyster protein was established.The results showed that dry basis was 18.5%of the oysters,and the dry basis chemical composition is,57.2%protien,33.0%total sugar,3.0%fat and6.4%ash.By comparing the four kinds of protein ratio of oyster protein composition,in this experiment,the oyster protein was ultimately extracted by pH regulation,eventually extraction process is under the condition of room temperature,adjusting pH to 12.0,alkaline conditions extracting for 1.0 h,centrifugal supernatant,and adjusting the pH to 4.0,centrifugal sedimentation.Finally,the protein purity was 84.37%,and the extraction rate of protein was 65.62%.2.Different proteases enzymolysis effect was investigated with ACE-inhibitory activity.By optimizing the enzymolysis conditions,the optimal enzymatic hydrolysis conditions was determine.The results show that the neutral protease enzymolysis exhibited the strongest ACE-inhibitory activity,digestion process is:hydrolyzing for 2 h,holding the temperature of 55?,pH8.0,E/S ratio of 3%,and solid-liquid ratio of 4%.Among them,IC₅₀=1.14±0.10 mg/mL.3.The process choosed molecular weight cut off?MWCO?for 3 kDa ultrafiltration membrane,and the ACE-inhibitory activity of WMCO 3 kDa?ONPH-B?is IC₅₀=0.66±0.06 mg/mL;The five component peaks were separated by the Sephadex LH-20,of which the ONPH-B-3 showed the greatest ACE-inhibitory activity,and after the reversed-phase high performance liquid chromatography elucidate,ONPH-B-3-4,ONPH-B-3-5 and ONPH-B-3-6 showed ACE-inhibitory activity.Again further purified by reverse phase high performance liquid chromatography,ONPH-B-3-4-2 and ONPH-B-3-5-2 have the highest ACE-inhibitory activity in ONPH-B-3-4,ONPH-B-3-5,respectively.Finally molecular mass of ONPH-B-3-5-2 is determinded 1017 Da;and molecular mass of ONPH-B-3-4-2 is 303 Da,including ONPH-B-3-4-2 structure for VW.4.Spontaneously hypertensive rats?SHR?was feed with ONPH-B?150 mg/kg?,and the Systolic blood pressure?SBP?changes was measured,daily.The results showed:Compared with the blank group,the oyster protein peptide group rats SBP had significant?p<0.05?changed in first day?SBP=197 mmHg?.Oyster protein peptide group compared with positive control group,positive control group in SBP significantly?p<0.01?lowered than oyster protein peptide groups in27 d?SBP=158.2 mmHg?;After 28 days of continuous gavage,the drug withdrawal observed 7 d,and the oyster peptide showed significant hypotensive effect.At the same time,the enzymolysis of oyster did not affect SHR's weight change.