Bioactive peptides identified in enzymatic hydrolyzates of milk caseins and method of obtaining same
The invention relates to the production of bioactive products that are derived from milk proteins for the production of bioactive milk products derived from milk proteins, particularly caseins. The 16 inventive peptides can be obtained chemically, biotechnologically or by means of enzymatic treatment from proteins containing same and give rise to peptides with an antimicrobial activity, an in vitro angiotensin converter inhibitor activity and/or antihypertensive activity and/or antioxidant activity. Said nutraceutical products are suitable for use in the food and pharmaceutical industries, both in the form of a hydrolyzate or bioactive peptides.
1. An isolated bioactive peptide wherein said peptide:
a. has Angiotensin-Converting-Enzyme (ACE)-inhibitory activity in vitro and/or antihypertensive activity in vivo and/or antioxidant activity,
b. is present in pepsin-hydrolyzed milk casein enzyme hydrolyzates, and
c. comprises a first tyrosine residue at the second position from the N-terminus and a second tyrosine residue at the fourth or fifth position from the N-terminus, and at least two hydrophobic amino acid residues in the C-terminal tripeptide sequence selected from the group consisting of proline, leucine and tyrosine; and
d. wherein said peptide has the amino acid sequence of SEQ ID NO. 12 or, and SEQ ID NO: 13.
2. The isolated bioactive peptide according to claim 1 , wherein said peptide is derived from α s2 -casein.
3. The isolated bioactive peptide according to claim 1 , wherein said peptide is derived from α s1 -casein.
4. The isolated bioactive peptide according to claim 1 , wherein said peptide has ACE-inhibitory activity in vitro.
5. The isolated bioactive peptide according to claim 1 , wherein said peptide has antihypertensive activity.
6. The isolated bioactive peptide according to claim 1 , wherein said peptide has antioxidant activity by oxygen radical chelation.
7. The isolated bioactive peptide according to claim 1 , wherein said peptide is obtained by a chemical or enzymatic synthesis method or by a recombinant method.
8. The isolated bioactive peptide according to claim 7 , wherein said peptide is obtained by enzymatic hydrolysis of α s1 -casein, or α s2 -casein.
9. An isolated bioactive product comprising, an enzymatic hydrolyzate, a fraction thereof or a purification of thereof, containing the isolated bioactive peptide of claim 1 .
10. The isolated bioactive peptide according to claim 1 , wherein the bioactive peptide has a leucine at the first or third position of the C-terminal tripeptide sequence.
11. The isolated bioactive peptide according to claim 1 , wherein the bioactive peptide has a tyrosine at first position of the C-terminal tripeptide sequence and has the amino acid sequence of SEQ ID NO: 12.
12. The isolated bioactive peptide according to claim 1 , wherein the bioactive peptide has a proline at the third position of the C-terminal tripeptide sequence and has the amino acid sequence of SEQ ID NO: 13.
13. A method for producing the isolated bioactive peptide according to claim 1 , wherein said method comprises
dissolving or dispersing casein or whole milk in water or a buffer solution to obtain a mixture;
optionally adjusting the mixture to a desired pH;
adding a proteolytic enzyme or proteolytic microorganism capable of digesting protein present in the casein or whole milk to the mixture; and
reacting the proteolytic enzyme or proteolytic microorganism with the protein for 10 minutes to 24 hours to obtain an isolated bioactive peptide according to claim 1 .
14. The method of claim 13 , wherein said method comprises
adjusting the mixture to a pH of 3.0,
reacting the proteolytic enzyme with the protein for 30 minutes to 3 hours,
wherein the proteolytic enzyme is pepsin which is added to the mixture at an enzyme-protein ratio.