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QIGLF, a novel angiotensin I-converting enzyme-inhibitory peptide from egg white protein
Zhipeng Yu1, Wenzhu Zhao, Jingbo Liu
1Laboratory of Nutrition and Functional Food, Jilin University, Changchun 130062, China.
Background:
Novel angiotensin I-converting enzyme (ACE)-inhibitory peptides from egg white protein can be rapidly screened by liquid chromatography/tandem mass spectrometry (LC/MS/MS). In this study, several peptides with higher ACE-inhibitory activity were prepared from egg white protein by enzymatic hydrolysis with Alcalase, purified with Sephadex G25, identified by LC/MS/MS and their structure determined by circular dichroism (CD) spectroscopy.
Results:
Peptide sequences DHPFLF, HAEIN and QIGLF that showed ACE-inhibitory activity were investigated further for their stability in gastrointestinal solution and for changes in their secondary structure in solution mixtures. QIGLF exhibited the highest activity (IC(50)=75 µmol L(-1)) and was resistant to digestion by proteases of the gastrointestinal tract. The CD spectrum of QIGLF showed the presence of the α-helix conformation.
Conclusion:
Three peptides were identified by LC/MS/MS and synthesised by Fmoc solid phase synthesis. Of the three, only the peptide sequence QIGLF was a potential ACE inhibitor, with an IC(50) value of 75 µmol L(-1) . Moreover, QIGLF showed low gastrointestinal enzyme susceptibility and contained a relatively high amount of α-helix.
