A Bovine Fibrinogen-Enriched Fraction as a Source of Peptides with in Vitro Renin and Angiotensin-I-Converting Enzyme Inhibitory Activities

Bovine fibrinogen is currently used in the food industry as a binding agent in restructured meat products. However, this protein is underused as a source of bioactive peptides. In this study, a number of novel angiotensin-I-converting enzyme (ACE-I) and renin inhibitory peptides were identified and enriched from a bovine fibrinogen fraction. Fibrinogen was isolated and enriched from bovine blood and hydrolyzed with the food-grade enzyme papain, which was selected for use using in silico analysis. The generated hydrolysate was subjected to ultrafiltration and its peptide profile characterized by liquid chromatography-tandem mass spectrometry. A number of peptides were identified and chemically synthesized to confirm their bioactivity in vitro. Identified peptides included the multifunctional tripeptide SLR, corresponding to f(35-37) of the beta-chain of bovine fibrinogen with ACE-I and renin IC50 values of 0.17 and 7.2 mM, respectively. Moreover, the resistance of identified peptides to gastrointestinal degradation and their bitterness were predicted using in silico methods.