Improving ACE inhibitory activity of hazelnut peptide modified by plastein: Physicochemical properties and action mechanism

doi:10.1016/j.foodchem.2022.134498

Food Chemistry

Volume 402, 15 February 2023, 134498

https://doi.org/10.1016/j.foodchem.2022.134498 Get rights and content

Highlights

•
Hazelnut-derived ACE-inhibiting peptides were first modified by plastein reaction.
•
N-terminal amino acid clustering contributed to the improved ACE inhibition rate.
•
Three novel ACE inhibitory peptides were reported.
•
YYLLVR had the highest ACE inhibitory activity with inhibition rate 89.10%.

Abstract

The plastein reaction can increase the activity of angiotensin-converting enzyme (ACE) inhibitory peptides, but the underlying mechanism is unknown. Hence, hazelnut protein hydrolysate and hazelnut peptide YLVR were used as substrate to explore the effect of plastein on physicochemical properties and the mechanism of structural change. The increase in turbidity and particle size and the decrease in free amino groups indicated that the reaction occurred via condensation. The modified products of YLVR were identified by NANO-HPLC-MS/MS, indicating that the N-terminal homologous amino acid aggregates in the plastein. Novel ACE inhibitory peptide YYLVR, YLLVR, and YYLLVR were synthesized and their inhibition rates were 66.35, 72.61, and 89.10 %, respectively, which were higher than that of YLVR (52.58 %). MD simulation showed that YYLLVR exhibited the lowest binding energies of −35.98 ± 2.30 kcal/mol to ACE. Taken together, plastein reaction is a promising strategy for inducing structural modifications to improve the activity of peptide.

Graphical abstract

Introduction

Angiotensin-I-converting enzyme (ACE) plays a key role in inducing hypertension in the body, and its activity can be inhibited by ACE inhibitory peptides (Wu, Liao, & Udenigwe, 2017). Food-derived ACE inhibitory peptides are considered natural substances that exhibit high biological activity, low toxicity, and are easily metabolized in the human body. These peptides are derived from food proteins and do not exhibit the side effects common with antihypertensive drugs. A review of various studies has proved that food-derived ACE inhibitory peptides have ACE inhibitory activity in vitro and in vivo (Aluko, 2015). An increasing number of food-derived peptides have been shown to have antihypertensive effects (Melanie & Andreas, 2019). Researchers believe that food-derived ACE inhibitory peptides may be used as an alternative therapy for patients with hypertension or its related diseases, and they can be added to functional foods for the prevention or adjuvant treatment of related diseases. (Guo et al., 2020).

The hazelnut proteins are valuable as multipurpose food ingredients. Aydemir, Gökbulut, Baran, and Yemenicioğlu (2014) reported the bioactive, functional and edible film making properties of hazelnut meal proteins. Proteins derived from hazelnut could be considered as a valuable source of peptides. It was proved that peptide of hazelnut gave almost 6 times more anti-hypertensive activity than hazelnut protein isolate (Eroglu & Aksay, 2017). Goksu, Cakir, and Gulseren (2022) found that some of the hazelnut protein fractions demonstrated considerable bioactivity (i.e., > 90 % ACE-inhibition) after simulated digestion. Simsek (2021) determined the bioactive potential of hazelnut meal protein hydrolysates, including ACE, dipeptidyl peptidase-IV, and α-glucosidase inhibitory potential. Previously, we also identified some hazelnut peptides, especially YLVR with strong ACE inhibitory activity (Liu, Fang, Min, Liu, & Li, 2018).

The plastein reaction is an enzymatic reaction wherein the amino acid sequence of certain peptides of a high concentration substrate are altered in the presence of a protease, due to which its sequence is potentially different from that of the raw protein, forming a protein mixture. The advantages of the plastein reaction are that there is no need to add non-protein components or unfavorable additives during the reaction, and the reaction conditions are mild. A neutrase-catalyzed plastein reaction was shown to enhance the ACE inhibitory activity of casein hydrolysate in vitro (Xu, Kong, & Zhao, 2014). Therefore, the plastein reaction provides a feasible method for modifying the functionality of peptides. However, there is currently a lack of knowledge about the changes in the peptide sequence after the plastein reaction, and there are few studies on the relationship between the structural changes and changes in ACE inhibitory activity.

In this study, for the first time, hazelnut-derived bioactive peptides were modified using the plastein reaction. Hazelnut protein hydrolysate was used as the substrate, and the degree of plastein reaction was judged by changes in turbidity, particle size and free amino groups. The relationship between the structural changes in the hazelnut protein hydrolysate and ACE inhibitory activity was determined by Fourier transform infrared spectroscopy. Furthermore, the ACE inhibitory peptide YLVR, isolated and purified from the hazelnut protein hydrolysate, was used as the substrate for plastein reaction modification. The modified mixture was analyzed by HPLC-MS/MS to identify changes in the peptide sequence, revealing the mechanism by which the plastein reaction improves the ACE inhibition rate of its product. Finally, molecular docking was used to analyze the structure–activity relationship between the change in peptide sequence and ACE inhibitory activity. The aim of this study was to explore the effect of plastein reaction on physicochemical properties and the mechanism of improved ACE inhibitory activity caused by structural change, which provides a theoretical basis for the design of peptides with strong ACE inhibitory activity.

Section snippets

Materials and chemicals

O-Phthalaldehyde (OPA), sodium dodecyl sulfate (SDS), and l-leucine were obtained from Solarbio (Beijing, China). Captopril, ACE (from rabbit lung) and N-Hippuryl-His-Leu hydrate (HHL) were obtained from Sigma-Aldrich (St. Louis, MO, USA). Alcalase 2.4 L was obtained from Novozymes (Bagsvaerd, Denmark). All other reagents were of analytical grade.

Preparation of hazelnut protein hydrolysates

Hazelnut protein hydrolysate was obtained according to the method described by Liu et al. (2018). Distilled water was added to the hazelnut protein to

Changes in the physicochemical properties of hazelnut hydrolysate after plastein reaction

Plastein is a protein-like product with a large molecular weight and low solubility (Li et al., 2020). The increase in insoluble matter results in an increase in the turbidity of the reaction system. Therefore, turbidity is considered to be one of the important indicators of plastein formation (Udenigwe et al., 2014). Fig. 1A shows the change of hazelnut protein hydrolysate solution turbidity before and after plastein reaction. Compared with the unmodified hydrolysate, the turbidity of the

Conclusion

In summary, the effects of plastein modification on the physicochemical properties of peptides and the resulting structural changes were investigated. The results showed that the ACE inhibition rate of the modified products was significantly improved. The increase in turbidity and particle size and the decrease in free amino groups indicated that the reaction occurred via condensation. YLVR was modified to verify the structure–activity relationship between the ACE inhibition rate and the

CRediT authorship contribution statement

Wentian Song: Conceptualization, Methodology, Investigation. Junxi Fu: Data curation. Qi Zeng: Validation, Formal analysis. Hongyan Lu: Data curation. Ji Wang: Software. Li Fang: Validation. Xiaoting Liu: Software. Weihong Min: Writing – review & editing, Supervision. Chunlei Liu: Writing – original draft, Supervision.

Declaration of Competing Interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

This work was supported by the Natural Science Foundation of Jilin Province (grant no. 20200201145JC) and projects funded by the Education Department of Jilin (No. JJKH20210345KJ).

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Improving ACE inhibitory activity of hazelnut peptide modified by plastein: Physicochemical properties and action mechanism

Highlights

Abstract

Graphical abstract

Introduction

Section snippets

Materials and chemicals

Preparation of hazelnut protein hydrolysates

Changes in the physicochemical properties of hazelnut hydrolysate after plastein reaction

Conclusion

CRediT authorship contribution statement

Declaration of Competing Interest

Acknowledgements

Food Hydrocolloids

Food Chemistry: X

Biotechnology Reports

Journal of Functional Foods

Food Chemistry

Food Chemistry

Food Chemistry

Computational Biology and Chemistry

Food Chemistry

International Journal of Biological Macromolecules

Ultrasonics Sonochemistry

Current Opinion in Food Science

Trends in Food Science & Technology

Ultrasonics Sonochemistry

Food Chemistry

Antihypertensive peptides from food proteins

Annual Review of Food Science and Technology

Investigation on the characteristics and mechanisms of ACE inhibitory peptides by a thorough analysis of all 8000 tripeptides via binding free energy calculation

Food Science & Nutrition

The application of the MM/GBSA method in the binding pose prediction of FGFR inhibitors

Physical Chemistry Chemical Physics