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. 2019 May 30;14(5):e0197644.
doi: 10.1371/journal.pone.0197644. eCollection 2019.

Identification, structure-activity relationship and in silico molecular docking analyses of five novel angiotensin I-converting enzyme (ACE)-inhibitory peptides from stone fish (Actinopyga lecanora) hydrolysates

Affiliations

Identification, structure-activity relationship and in silico molecular docking analyses of five novel angiotensin I-converting enzyme (ACE)-inhibitory peptides from stone fish (Actinopyga lecanora) hydrolysates

Shehu Muhammad Auwal et al. PLoS One. .

Abstract

Stone fish is an under-utilized sea cucumber with many health benefits. Hydrolysates with strong ACE-inhibitory effects were generated from stone fish protein under the optimum conditions of hydrolysis using bromelain and fractionated based on hydrophobicity and isoelectric properties of the constituent peptides. Five novel peptide sequences with molecular weight (mw) < 1000 daltons (Da) were identified using LC-MS/MS. The peptides including Ala-Leu-Gly-Pro-Gln-Phe-Tyr (794.44 Da), Lys-Val-Pro-Pro-Lys-Ala (638.88 Da), Leu-Ala-Pro-Pro-Thr-Met (628.85 Da), Glu-Val-Leu-Ile-Gln (600.77 Da) and Glu-His-Pro-Val-Leu (593.74 Da) were evaluated for ACE-inhibitory activity and showed IC50 values of 0.012 mM, 0.980 mM, 1.310 mM, 1.440 mM and 1.680 mM, respectively. The ACE-inhibitory effects of the peptides were further verified using molecular docking study. The docking results demonstrated that the peptides exhibit their effect mainly via hydrogen and electrostatic bond interactions with ACE. These findings provide evidence about stone fish as a valuable source of raw materials for the manufacture of antihypertensive peptides that can be incorporated to enhance therapeutic relevance and commercial significance of formulated functional foods.

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Conflict of interest statement

The authors have declared that no competing interests exist.

Figures

Fig 1
Fig 1
Hydrophobicity-based fractionation of bromelain-generated stone fish protein hydrolysate (a) Chromatogram of semi-preparative RP-HPLC; (b) ACE-inhibitory activities of each of the potent fraction; (c) Relation between ACE-inhibitory activity and percentage acetonitrile being used.
Fig 2
Fig 2. ACE-inhibitory activity of bromelain-generated stone fish protein hydrolysate fractions at different isoelectric points along a pH gradient (3–10).
Fig 3
Fig 3
MS/MS spectra, ion tables, MS/MS fragments and standard error of the potent peptide sequences with mw < 1000 Da: (a) Ala-Leu-Gly-Pro-Gln-Phe-Tyr (b) Lys-Val-Pro-Pro-Lys-Ala (c) Leu-Ala-Pro-Pro-Thr-Met (d) Glu-Val-Leu-Ile-Gln (e) Glu-His-Pro-Val-Leu.
Fig 4
Fig 4. Predicted mode of binding of peptides and captopril docked to ACE.
(a) Ala-Leu-Gly-Pro-Gln-Phe-Tyr (b) Lys-Val-Pro-Pro-Lys-Ala (c) Leu-Ala-Pro-Pro-Thr-Met (d) Glu-Val-Leu-Ile-Gln (e) Glu-His-Pro-Val-Leu and (f) Captopril. Peptides are indicated as green lines, ACE residues are depicted as ribbon sticks, Different mode of interaction and selected distances are illustrated by dash lines and zinc ions are shown as cyan spheres.
Fig 5
Fig 5
Predicted binding site for the 2D interaction of stone fish-derived ACE-inhibitory peptides with molecular surface of ACE; (a) Ala-Leu-Gly-Pro-Gln-Phe-Tyr (b) Lys-Val-Pro-Pro-Lys-Ala (c) Leu-Ala-Pro-Pro-Thr-Met (d) Glu-Val-Leu-Ile-Gln (e) Glu-His-Pro-Val-Leu and (f) Captopril as predicted by Schrödinger software.

References

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