Research On Characterization And Stability Of Angiotensin Converting Enzyme Inhibitory Peptides From Egg White

The research was granted by 863 research program (No.2007AA10Z329). The aim of this study was to identify potential angiotensin I-converting enzyme (ACE) inhibitory peptide from egg white protein. The egg white protein was hydrolyzed by Alcalase 2.4 L and the hydrolysates were isolated with Gel filtration to get the high activity fraction. The fraction was identified by LC tandem mass spectrometric 4000 Q Trap MS, and peptides sequence were RVPSLM, TPSPR, DLQGK, AGLAPY, RVPSL, DHPFLF, HAEIN and QIGLF, respectively.In the current work, egg white protein derived peptides were discovered by the potential applications of Q TRAP.1) ACE-inhibitory activity based on Cushman method with some modification, was conducted in borate buffer (100 mM, pH 8.3) containing 300 mM NaCl. A total reaction volume of 60μL contained 100 mM borate buffer (pH 8.3),30μL 4 mM Hip-His-Leu (HHL),10μL sample solution, and 20 pL 10 milliunit ACE. All solutions were incubated at 37℃for 30 min in a thermostatically controlled water bath prior to mixing, and for an additional 30 min at the same temperature after mixing. The reaction was stopped by adding 60μL 1 M HCL before injecting the sample into the HPLC sample loop to quantify the HA produced by the enzymatic hydrolysis of the substrate hipuryl-Lhistidyl-L-leucine.2) Egg white protein was hydrolyzed by Alcalase according to a regression orthogonal and combination model. Based on Sylvester Inequality, the maximum value of the equation has been proved to exist.The optimization enzymolysis condition was concentration of substrate 8%, pH 10.73, E/S 12%, temperature 56.8℃.3) The stability properties of antihypertensive peptides against chemistry was evaluated by Plackett-Burman Design, and the stability in simulated gastrointestinal condition was investigated by determining the change of angiotensin converting enzyme inhibition activity. The results showed that chemistry factors had no significance in the stability of the angiotensin converting enzyme inhibitory activity, and the antihypertensive peptides had sensitive stability against pepsin and trypsin.4) The egg white protein was hydrolyzed by Alcalase 2.4 L and the hydrolysates were isolated with Gel filtration. The high activity fraction was identified by LC tandem mass spectrometric 4000 Q Trap MS, and peptides sequence were RVPSLM, TPSPR, DLQGK, AGLAPY, RVPSL, DHPFLF, HAEIN and QIGLF, respectively5) The peptide derived from egg white was synthesized by the solid phase procedure peptide using FMOC protected amino acids synthesis methods. The peptides were measured by the HPLC method. Peptides RVPSL, QIGLF have the higher activity and the values of IC50 were 20μM,75μM, respectively.