Selection of goat ß-casein derived ACE-inhibitory peptide SQPK and insights into its effect and regulatory mechanism on the function of endothelial cells.

The angiotensin I-converting enzyme (ACE)-inhibitory peptide SQPK was selected by in silico digestion and virtual screening from goat ß-casein, and its effect and regulatory mechanism on function of endothelial cells was further evaluated. The results showed that SQPK exhibited relatively good ACE inhibition capacity (IC50 = 452.7 µg/mL). Treatment with 25 µg/mL SQPK for 12 h significantly elevated nitric oxide (NO) production, stimulated eNOS expression (p < 0.05) and affected the transcriptomic profiling of EA. Hy926 cells. In particular, SQPK stimulated the expression of genes encoding inflammatory cytokines (CXCL1/2 and IL6) but depressed encoding mesenchymal markers (FN1 and CNN3). Furthermore, SQPK modified the expression of genes involved in endothelial-to-mesenchymal transition (EndMT). Therefore, the selected peptide SQPK may exert potential protective effects on the function of endothelial cells by inhibiting the EndMT.