Angiotensin I-converting enzyme inhibitory activity in milk fermented by wild-type and peptidase-deletion derivatives of Lactobacillus helveticus CNRZ32

• Published in: International dairy journal Vol. 17; no. 8; pp. 976 - 984
• Main Authors: Kilpi, E.E.-R., Kahala, M.M., Steele, J.L., Pihlanto, A.M., Joutsjoki, V.V.
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.08.2007; Elsevier Science
• Subjects: ACE-inhibitory activity; aminopeptidases; antihypertensive agents; antihypertensive effect; Biological and medical sciences; enzyme inhibitors; Fermentation; fermented milk; food analysis; Food industries; functional foods; Fundamental and applied biological sciences. Psychology; in vitro culture; lactic acid bacteria; Lactobacillus helveticus; Milk and cheese industries. Ice creams; molecular genetics; mutants; Peptidase; Proteolysis; renin; starter cultures; strains; X-prolyl dipeptidyl aminopeptidase; ACE-inhibitory activity; Lactobacillus helveticus; Peptidase; Fermentation; Proteolysis; Enzyme; Dairy product; Peptidases; Angiotensin; Dairy industry; Deletion; Bacteria; Hydrolases; Lactobacillaceae; Cultured milk
• ISSN: 0958-6946; 1879-0143
• DOI: 10.1016/j.idairyj.2006.12.001

Development of molecular methods has enabled detailed studies of the proteolytic system of Lactobacillus helveticus, which has a central role in the release of bioactive peptides during the fermentation of milk. The impact of general aminopeptidase (PepN) and X-prolyl dipeptidyl aminopeptidase (PepX) activity of L. helveticus on the level of angiotensin I-converting enzyme (ACE) inhibitory activity in fermented milk was elucidated by taking advantage of peptidase-negative derivatives of L. helveticus CNRZ32. According to the results, increased level of ACE-inhibitory activity was attained in milk fermented by the peptidase-deficient mutants. The ACE-inhibitory activity determined with the PepN-deficient strain decreased towards the end of fermentation, suggesting that PepN gives rise to a provisional accumulation of ACE-inhibitory peptides before their hydrolysis to shorter peptides or free amino acids. The ACE-inhibitory activity determined with the PepX-deficient strain increased throughout the fermentation, indicating specific blocking of the further hydrolysis of ACE-inhibitory peptides.