Angiotensin I-Converting-Enzyme-Inhibitory and Antibacterial Peptides from Lactobacillus helveticus PR4 Proteinase-Hydrolyzed Caseins of Milk from Six Species

Abstract

Sodium caseinates prepared from bovine, sheep, goat, pig, buffalo or human milk were hydrolyzed by a partially purified proteinase of Lactobacillus helveticus PR4. Peptides in each hydrolysate were fractionated by reversed-phase fast-protein liquid chromatography. The fractions which showed the highest angiotensin I-converting-enzyme (ACE)-inhibitory or antibacterial activity were sequenced by mass spectrum and Edman degradation analyses. Various ACE-inhibitory peptides were found in the hydrolysates: the bovine ␣ S1 -casein (␣ S1 -CN) 24-47 fragment (f24-47), f169-193, and ␤-CN f58-76; ovine ␣ S1 -CN f1-6 and ␣ S2 -CN f182-185 and f186-188; caprine ␤-CN f58-65 and ␣ S2 -CN f182-187; buffalo ␤-CN f58-66; and a mixture of three tripeptides originating from human ␤-CN. A mixture of peptides with a C-terminal sequence, Pro-Gly-Pro, was found in the most active fraction of the pig sodium caseinate hydrolysate. The highest ACE-inhibitory activity of some peptides corresponded to the concentration of the ACE inhibitor (S)-N-(1-[ethoxycarbonyl]-3-phenylpropyl)-ala-pro maleate (enalapril) of 49.253 g/ml (100 mol/liter). Several of the above sequences had features in common with other ACE-inhibitory peptides reported in the literature. The 50% inhibitory concentration (IC 50 ) of some of the crude peptide fractions was very low (16 to 100 g/ml). Some identified peptides were chemically synthesized, and the ACE-inhibitory activity and IC 50 s were confirmed. An antibacterial peptide corresponding to ␤-CN f184-210 was identified in human sodium caseinate hydrolysate. It showed a very large spectrum of inhibition against gram-positive and -negative bacteria, including species of potential clinical interest, such as Enterococcus faecium, Bacillus megaterium, Escherichia coli, Listeria innocua, Salmonella spp., Yersinia enterocolitica, and Staphylococcus aureus. The MIC for E. coli F19 was ca. 50 g/ml. Once generated, the bioactive peptides were resistant to further degradation by proteinase of L. helveticus PR4 or by trypsin and chymotrypsin.

Bioactive peptides released from in vitro digestion of human milk with or without pasteurization

“…The most abundant peptides are derived from β-CN, reflecting its high susceptibility to plasmin-mediated proteolysis as well as the high content of this casein subunit in HM (14,16). Focusing on bioactive peptides in undigested HM, as shown in Table 1 (14,15,(17)(18)(19)(20)(21)(22)(23)(24)(25)(26)(27)(28)(29)(30), two caseinophosphopeptide homologues, a possible opioid peptide or propeptide, and an antibacterial peptide were identified.…”

“…Thus, gastrointestinal digestion would be required for the formation of these shorter bioactive peptide and they would be released from intact β-CN as well as the precursor peptide (residues 51-59). The last bioactive peptide in undigested HM was a peptide of residues 185-211, known as an antibacterial peptide (24). This peptide was also In the amino acid sequence column, peptides in italic indicate possible precursors for bioactive peptides, which include bioactive sequences.…”

Camel Milk: An Important Natural Adjuvant

“…Angiotensin I-Converting Enzyme (ACE) Inhibitory Activity ACE-inhibitory peptides are present in the primary structure of various food protein sources including milk proteins [50,69,80,81]. These peptides are also found in fermented camel milk [86].…”

DNA microarray analysis of the antihypertensive effect of milk fermented by Lactobacillus helveticus H9 on spontaneously hypertensive rats

“…It has been proposed that it is the milk-derived peptides in fermented milk products that could be a primary factor conferring the antihypertensive effect. In particular, groups of bioactive peptides with properties such as angiotensin-converting enzyme (ACE) inhibition, opioid-like activities, mineral-binding activity, and antithrombotic activity could be associated with the antihypertensive effect (Minervini et al 2003). Although many studies have demonstrated that bioactive peptides in fermented milk can reduce blood pressure (Foltz et al 2007), the molecular mechanisms for this effect are still not clear.…”