Identification of Angiotensin I-Converting Enzyme Inhibitors in Peptides Mixture of Hydrolyzed Red Deer Plasma with Proteomic Approach

Proteomics is a rapidly emerging set of key technologies that are of major importance for proteins and drug development process, especially when mass spectrometry (MS) is being used for high-throughput characterization and identification of proteins. Since the safer and healthier angiotensin I-converting enzyme (ACE) inhibitors are extremely concerned, many research groups have combed for novel ACE inhibitors from food components by different approaches. Here, shotgun proteomics technology aided with structure-activity analysis was applied to screen ACE inhibitory peptides from hydrolyzed red deer plasma. The peptides were analysed by mass spectrometry after primary separation with Sephadex G-25 chromatography. 36 peptides were identified by searching red deer database and 165 peptide sequences derived were identified in mammalian database. Amino acid sequences of peptide and bioactivity relationship have been developed as a faster and useful way to predict and screen new inhibitors. Depending on the relationship of peptide structure and ACE inhibitory activity, a nonapeptide, VYNEGLPAP, was predicted with ACE inhibitory activity. The activity was verified by synthesized VYNEGLPAP and the 50% inhibition concentration (IC50) was 3.1 mu mol center dot L-1. VYNEGLPAP had good thermal stability, pH stability and strong enzyme-resistant properties against gastrointestinal protease. Kinetic experiments demonstrated that inhibitory kinetic mechanism of this peptide was competitive. This study demonstrated the possibility of screening bioactive peptides from protein hydrolysates mixture based on shotgun proteomics technology, which will provide a potential convenient method to screening bioactive peptides from protein source.