Paiva, Lisete S.Lima, ElisabeteNeto, Ana I.Baptista, José2022-03-112022-03-112016-10Paiva, L., Lima, E., Baptista, J., & Neto, A. I.. (2016). Isolation and characterization of angiotensin I-converting enzyme (ACE) inhibitory peptides from Ulva rigida C. Agardh protein hydrolysate. “Journal of Functional Foods”, 26, 65–76. https://doi.org/10.1016/j.jff.2016.07.0061756-4646http://hdl.handle.net/10400.3/6239Ulva rigida protein was hydrolysed with pepsin plus bromelain after a screening of nine enzymes for optimal proteolysis. This hydrolysate, presenting ACE-inhibitory activity with an IC₅₀ value of 0.483 mg/mL, was fractionated by ultrafiltration membranes into three molecular weight ranges (<1 kDa, 1–3 kDa and >3 kDa). The <1 kDa fraction that exhibited the highest activity (IC₅₀: 0.095 mg/mL) was purified using size-exclusion chromatography and reversed-phase high-performance liquid chromatography, yielding two active ACE-inhibitory purified peptides. Edman degradation revealed its amino acid sequences to be IP and AFL with IC₅₀ values of 0.020 and 0.023 mg/mL, respectively. Both peptides were synthesized to confirm the structure and to validate their ACE-inhibitory activities. Lineweaver–Burk plots suggest that IP acts as a non-competitive and AFL as a competitive ACE-inhibitors. Stability assays showed that both peptides are heat-stable and AFL is hydrolysed by intestinal mucosa peptidases to FL with IC₅₀ value of 0.004 mg/mL that acts as a non-competitive ACE-inhibitor. The results suggest that these peptides might have a potential use in the preparation of antihypertensive drugs or functional foods.engACE-inhibitory PeptidesEnzymatic HydrolysisHypertensionInhibition KineticMacroalgaeSimulated Gastrointestinal Digestionjournal article2022-01-28cv-prod-268709310.1016/j.jff.2016.07.006000386193400007