Yeast protease B‐digested skimmed milk inhibits angiotensin‐I‐converting‐enzyme activity

Abstract

Angiotensin-1-converting-enzyme (ACE) inhibitory activity was identified in skimmed milk digested with cell-free extract of yeast Saccharomyces cerevisiae. Simultaneously, a protease enzyme involved in the production of ACE-inhibition materials in digested skimmed milk was purified to homogeneity from the cell-free extracts of S. cerevisiae by ammonium sulphate fractionation and chromatography in DEAE-Sephacel, D-tryptophan methyl ester-Sepharose 4B, Hiload Superdex G-200 and HPLC Mono-Q chromatography. The purified enzyme was identified as protease B, based on the molecular mass on SDS/PAGE and the N-terminal amino acid sequence of the enzyme. The optimum pH for digestion of skimmed milk and production of ACE-inhibition materials was pH 4.8. The IC(50) of the hydrolysate was 0.42 mg of protein/ml when skimmed milk was digested with yeast protease B.

Proteolytic activity of dairy lactic acid bacteria and probiotics as determinant of growth and in vitro angiotensin-converting enzyme inhibitory activity in fermented milk

“…Similar results were reported by Pihlanto-Leppalla et al [31] using different lactic acid staters and digestive enzymes to obtain inhibition of 35 to 86% and IC 50 values between 0.080 to 0.314 mg·mL -1 . Several milk protein-derived peptides produced by the enzymatic hydrolysis [33] or by the fermentation of milk with different strains of organisms [18,23] inhibited the activity of ACE.…”

ACE-inhibitory activity of milk fermented with Saccharomyces cerevisiae K7 and Lactococcus lactis subsp. lactis NBRC 12007

“…The higher peptide concentration observed in the milk fermented with the co-culture may be due to the combined proteolytic actvity of the two strains. It has been reported that the yeast protease B activity of S. cerevisiae is optimal at pH 4.8 (Roy et al, 2000). This could be the main reason for the increase in peptide concentration in the milk fermented with S. cerevisiae K7 during the latter part of the fermentation once its pH reached 4.8.…”

“…It is obvious that thermophilic Lactobacillus and S. cerevisiae is an effective combination in producing fermented milk products with antihypertensive properties. The ability of S. cerevisiae`s proteolytic enzymes to hydrolyze milk proteins to ACE-inhibitory peptides has been reported earlier (Roy et al, 2000), whereas ACE-inhibitory activity was detected in fermented whey supplied with 20 g/L D-glucose and fermented with S. cerevisiae in monoculture and in co-culture with Lb. helveticus (Vermeirssen et al, 2003).…”

“…helveticus. The ability of S. cerevisiae to grow in milk and to hydrolyze milk proteins into ACEinhibitory peptides have been well documented (Roy et al, 2000;Vermeirssen et al, 2003). S. cerevisiae K7 is widely utilized in the manufacture of 'sake', which is well-known for its high proteolytic activity.…”

“…These peptides are inactive within the sequence of precursor proteins, but can be released in vivo or in vitro by enzymatic digestion or during fermentation with lactic acid bacteria (LAB) (Gobbetti et al, 2000;Roy et al, 2000;De Noni & Cattaneo, 2010). During microbial fermentation of milk, proteins are hydrolyzed into long oligopeptides by cell wall associated proteinases of LAB, transported into the cell and broken down by intracellular peptidases into a range of peptides with different bioactivities (Nielsen et al, 2009).…”