Screening and Constructing of Novel Angiotensin I-Converting Enzyme Inhibiting Peptides from Walnut Protein Isolate and Their Mechanisms of Action: A Merged In Silico and In Vitro Study

• Published in: Plant foods for human nutrition (Dordrecht) Vol. 79; no. 1; pp. 48 - 58
• Main Authors: Wang, Yuzhen, Tang, Hengkuan, Deng, Xinyue, Shen, Yijie, Tang, Mingjian, Wang, Fengjun
• Format: Journal Article
• Language: English
• Published: New York Springer US 01.03.2024; Springer Nature B.V
• Subjects: Angiotensin; Angiotensin I; Angiotensin-converting enzyme inhibitors; Biocompatibility; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Chromatography; Ecology; Enzymes; Food Science; Functional foods & nutraceuticals; Hydrogen bonding; Hydrolysates; Ion exchange; Liquid chromatography; Mass spectrometry; Mass spectroscopy; Molecular docking; Nitric oxide; Nutrition; Peptides; Peptidyl-dipeptidase A; Physicochemical properties; Plant Physiology; Proteins; Screening; Separation; Stability analysis; Toxicity; Ultrafiltration; Ultrasonic processing; Walnuts; Replacement peptides; Cell viability; ACE-inhibiting peptides; Nitric oxide; Walnut protein isolate; Molecular docking
• ISSN: 0921-9668; 1573-9104
• DOI: 10.1007/s11130-023-01122-1

Angiotensin I-converting enzyme (ACE)-inhibiting peptides were isolated from walnut protein isolate (WPI) using ultrasound-assisted extraction. This study aimed to assess the impact of ultrasonic pretreatment on the physicochemical properties of WPI. The optimal extraction conditions for WPI were determined as a 15-min ultrasonic treatment at 400 W. Subsequently, the hydrolysate exhibiting the highest in vitro ACE-inhibiting activity underwent further processing and separation steps, including ultrafiltration, ion exchange chromatography, liquid chromatography-tandem mass spectrometry, ADMET screening, and molecular docking. As a result of this comprehensive process, two previously unidentified ACE-inhibiting peptides, namely Tyr-Ile-Gln (YIQ) and Ile-Tyr-Gln (IYQ), were identified. In addition, a novel peptide, Ile-Lys-Gln (IKQ), was synthesized, demonstrating superior ACE-inhibiting activity and temperature stability. In silico analysis estimated an in vivo utilization rate of 21.7% for IKQ. These peptides were observed to inhibit ACE through an anti-competitive mechanism, with molecular docking simulations suggesting an interaction mechanism involving hydrogen bonding. Notably, both IYQ and IKQ peptides exhibited no discernible toxicity to HUVECs cells and promoted nitric oxide (NO) generation. These findings underscore the potential of ultrasonicated WPI in the separation of ACE-inhibiting peptides and their utility in the development of novel ACE inhibitors for functional food applications.