Peptide properties

1Top 2Function-activity relationship 3Calculated physicochemical properties 4Peptide source & Food-borne protein(s) search 5Biological/Functional activity & target protein 6Taste properties & Structure 7Preparation method 8Stability & Cytotoxicity 9Additional information 10Database cross-references 11Reference(s)

List of peptide properties

DFBP ID - DFBPACEI1800(ACE-inhibitory peptide)

DFBP ID	DFBPACEI1800
Peptide sequence	LKKISQ
Type	Native peptide
Peptide/Function name	ACE-inhibitory peptide

Function-activity relationship

Main bioactivity	ACE-inhibitory activity
Otheir bioactivity	Antioxidative activity ^[D1], Antimicrobial activity ^[D2], Multifunctional activity ^[D3]

Calculated physicochemical properties

Three-letter amino acid

Leu-Lys-Lys-Ile-Ser-Gln

Single-letter amino acid

LKKISQ

Peptide length

Peptide mass

Experimental mass	Theoretical mass
715.4 Da	715.88 Da ^c

Net charge

0.00 ^c

Isoelectric point (pI)

10.59 ^c

IC₅₀

2.6 uM ^[1]

pIC₅₀

-0.415

GRAVY

-0.6333^c

Hydrophilic residue ratio

33.33%^c

Peptide calculator

Peptide source & Food-borne protein(s) search

Classification	Animal
Organism/Source	Manchego cheeses, Ovine milk protein
Precursor protein	α_s2-Casein
Residue position	f(165-170)
Precursor protein(s) search	Source.1: DFBPPR7689 ---- Milk proteins ---- Alpha-S2-casein Source.2: DFBPPR7701 ---- Milk proteins ---- Alpha-S2-casein Source.3: DFBPPR8494 ---- Milk proteins ---- Alpha-S2-casein
Link-research Inductive analysis	There are no literature reports on the discovery of this sequence in other food-source proteins.

Biological/Functional activity & target protein

ACE-inhibitory activity

(1) The peptide exhibited strong Angiotensin-Converting Enzyme (ACE) (EC 3.4.15.1) inhibitory activity with an IC₅₀ value of 2.6 μM ^[1].
(2) The fraction F3.3 of water-soluble extracts from Manchego cheeses (containing peptide LKKISQ) showed potent ACE-inhibitory activity, so the peptide was a potential ACE-inhibitory peptide, as shown in Table 1.

Table 1. Identification of the peptides contained in the analytical RP-HPLC fractions with ACE-inhibitory activity
Fraction	Protein fragment	Sequence	Protein content (μg/mL) ^a	% ACE inhibition ^a
F3.3	β-casein f(95-101)	VPKVKET	13.5 ± 0.2	79.6 ± 3.0
	α_s2-casein f(165-170)	LKKISQ
^a Average values ± standard deviation (n = 3).

Specific target protein(s)

Specific Target Protein(s):
Angiotensin-converting enzyme

Taste properties & Structure

Bitterness

Literature report	N.D
Bitter prediction tools	No prediction can be made about the peptide bitterness. ^prediction

SMILES

N[C@@]([H])(CC(C)C)C(=O)N[C@@]([H])(CCCCN)C(=O)N[C@@]([H])(CCCCN)C(=O)N[C@@]([H])([C@]([H])(CC)C)C(=O)N[C@@]([H])(CO)C(=O)N[C@@]([H])(CCC(=O)N)C(=O)O

Preparation method

Mode of preparation

Fermentation, Enzymatic hydrolysis

Enzyme(s)/starter culture

(1) Fermentation: The peptide was isolated from the water-soluble extract of a ripened Manchego cheese (Type 1: Expermental batches of pasteurised-milk cheeses was prepared by inoculating milk with Lactococcus lactis subsp. lactis (80%) and Leuconostoc mesenteroides subsp. dextranicum (20%)).
(2) Enzymatic hydrolysis: Peptide obtained by hydrolysis of ovine α_s2-casein by use of porcine pepsin A ^[1].

Stability & Cytotoxicity

Peptide stability

Literature report:	N.D
EHP-Tool:	Enzymatic Hydrolysis Prediction Tool (EHP-Tool)

Peptide cytotoxicity

Literature report:	N.D
Prediction:	ToxinPred

Additional information

The potential of the peptide for its use in functional foods to mitigate hypertension would seem to merit further investigation using animal in vivo assays.

Database cross-references

DFBP

[D1]	DFBPANOX0716
[D2]	DFBPAMIC0186
[D3]	DFBPMUFU0537

[D4]

[D5]

[D6]

[D7]

Reference(s)

Primary literature	Gómez-Ruiz, J.Á., Ramos, M., Recio, I. Angiotensin-converting enzyme-inhibitory peptides in Manchego cheeses manufactured with different starter cultures. International Dairy Journal. 2002, 12, 697-706. DOI: 10.1016/S0958-6946(02)00059-6
Other literature(s)	[1] Lopez-Exposito, I., et al., Casein hydrolysates as a source of antimicrobial, antioxidant and antihypertensive peptides. Lait, 2007. 87(4-5): p. 241-249. [2] Park Y W. Bioactive Components in Milk and Dairy Products[M]. 2009. [3] LóPezexpóSito I, Gomezruiz J A, Amigo L, et al. Identification of antibacterial peptides from ovine αs2-casein[J]. International Dairy Journal, 2006, 16(9):1072-1080.
PubDate	2002