Structure and ACE-Inhibitory Activity of Peptides Derived from Hen Egg White Lysozyme

Angiotensin I-converting enzyme plays an important role in hypertension and therefore its inhibition is considered to be a useful procedure in the prevention of hypertension. Two novel ACE inhibitory peptides were purified and identified from the papain-trypsin hydrolysate of hen egg white lysozyme using reverse phase-high performance liquid chromatography. The sequences of identified peptides were NTDGSTDYGILQINSR (MW: 1,753.98?±?0.5?Da) and VFGR (MW: 459.26?±?0.5?Da), which were named F2 and F9 peptide, respectively. Analyses of the far-UV CD spectra of ACE in the absence and presence of the F2 peptide revealed ACE secondary structural changes. In the presence of the F2 peptide, a loss of helical content of ACE was observed, which can lead to decrease of the enzymatic activity. Lineweaver?CBurk plots show that the identified peptides both act as non-competitive ACE inhibitors. These findings would be helpful on the understanding of interaction between ACE and its inhibitory peptides.