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liquor to improve human health.
Therefore, ecology, quality and health are the development trends
of China's liquor industry.
In recent years, the non-volatile trace components in liquor that benefit human health are gradually being discovered, and functional oligopeptides are favored by researchers in this field as a kind of endogenous health factors produced in the brewing process of liquor
.
At present, researchers have found four peptide compounds
, including lichenin, cyclic dipeptide, antioxidant peptide, angiotensin-converting enzyme (ACE) inhibitory peptide, etc.
in different aroma types of liquor, clear fragrance and sauce aroma.
The endogenous oligopeptides of baijiu not only have certain physiological functions, but also some oligopeptides with special sequences/structures also make baijiu show taste characteristics such as sweetness, bitterness, sourness and saltiness.
In addition, oligopeptides can interact with aroma or odor components, affect the volatilization performance of the latter, and play a role in long-lasting fragrance retention, changing the aroma type of liquor, and masking odor
。 For example, lichenysin can selectively inhibit the volatilization performance of aroma compounds in sauce-flavored, fragrant and clear-flavored liquor, among which the inhibitory effect on alcohols, aldehydes and other compounds is the most obvious, followed by long-chain esters, but has no effect on the volatilization of short-chain esters; Further studies have found that lichenin can form hydrogen bonds with the phenolic hydroxyl group of odor component 4-ethylguaiacol through the carboxylic acid oxygen of its valine, thereby preventing its premature release to the outside world and effectively reducing the odor intensity of liquor.
The liquor antioxidant peptide Ala-Lys-Arg-Ala improves the stables flavor caused by 4-methylphenol in liquor by forming hydrogen bonds with hydroxyhydrogen of p-4-methylphenol
.
Therefore, the endogenous functional oligopeptides of baijiu have important application value: 1) as potential flavor substances, making the taste of baijiu more complex and rich; 2) There is intermolecular interaction with aroma compounds, inhibit the volatilization performance of odor, change the aroma characteristics of liquor, and make the aroma more coordinated and durable; 3) It has potential physiological functions
in the human body.
Based on the research of predecessors, Professor Yu Yougui and Dr.
Wu Qiang of Shaoyang University and Zhong Changqing of the First Affiliated Hospital of Hunan Normal University isolated and identified the oligopeptide Gln-Gly-Val-Pro (QGVP) with significant ACE inhibitory activity from liquor lees, explored the ACE inhibition mechanism by molecular docking and circular dichromatographic analysis, and further established the Ang I-induced model of human umbilical vein endothelial cells (HUVECs) to explore the molecular mechanism
of its treatment of hypertension 。 Fig.
1 Abstract Results and Discussion: In this study, crude ACE inhibitory peptide was prepared by using double-enzyme directed enzymatic hydrolysis technology to degrade aromatic liquor lees under optimized conditions, and the pure ACE inhibitory peptide product was further separated and purified by ultrafiltration and high performance liquid chromatography (HPLC), and the amino acid sequence was identified as QGVP
by electrospray mass spectrometry (ESI-MS).
。 The molecular docking 3D and 2D structures are shown in Figure 2A, and the interaction between QGVP and ACE is mainly hydrogen bonds and van der Waals forces, in which QGVP forms 6 hydrogen bonds
with Tyr360, Asp358, Ala356, Ser355, Asn66 and Asn70 amino acid residues in the active region of ACE S1'pocket 。 CD analysis showed that the secondary structure of ACE was mainly composed of α-helix, with two negative bands at 208 nm and 222 nm and a positive band at 190 nm.
However, after QGVP binds to ACE, they change, indicating that QGVP causes ACE conformational changes (Figure 2B).
In addition, the calculation of secondary structure content by CDNN software shows that the combination of QGVP and ACE leads to a decrease in the content of α-helix structure of ACE and an increase
in the content of β-corner structure.
Therefore, it is speculated that QGVP binds to the S1′ active bag of ACE by forming a hydrogen bond, which changes the secondary structure of ACE, resulting in inactivation
of ACE.
Fig.
2 Mechanism of inhibition of ACE by QGVP ACE is usually located in the vascular endothelial cell membrane, which plays an important role
in vascular tone and blood pressure regulation by regulating vasoactive substances and stimulating the release of vasodilator factor NO or vasoconstrictor factor END1.
Angiotensin receptor type 1 (ANGR1) binds to G protein-coupled receptors, causing hypertension, fibrosis, and inflammation
in cardiovascular disease.
The study found that QGVP was incubated with HUVECs for 24 h in the concentration range of 25~400 μg/mL, and the cell viability did not decrease
significantly.
With the increase of QGVP concentration, HUVEC intracellular Ang II levels gradually decreased (Figure 3), in which HUVEC intracellular Ang II concentration decreased
sharply after 200 μg/mL QGVP protection compared to the Ang I induction group.
In addition, compared with the Ang I group, QGVP treatment significantly increased the expression level of eNOS mRNA and was dose-dependent, but decreased the expression level
of END1 mRNA.
Protein expression analysis further confirmed that QGVP treatment stimulated eNOS phosphorylation and inhibited END1 protein expression levels (Figure 3).
Among them, under the action of 200 μg/mL QGVP, the expression of Ang I-induced p-eNOS protein was upregulated by nearly 5.
2 times
.
Fig.
3 Regulation of QGVP on the expression
of target genes of Ang I-induced HUVEC cells In this study, the active oligopeptide QGVP was isolated from the aromatic liquor lees, which could form 6 hydrogen bonds with amino acid residues in the active region of ACE, and the content of ACE α-helix structure was reduced after the oligopeptide was detected to bind to ACE, and it was speculated that ACE may be inactivated
due to conformational changes 。 In addition, QGVP not only has no cytotoxicity to HUVEC, but can promote eNOS phosphorylation and inhibit END1 expression in Ang I-induced HUVEC, thereby exerting vasodilating effects
.
Therefore, QGVP is expected to be used as a food ingredient, for prophylaxis, or developed with other chemical drugs for the treatment of hypertension
.
First author
Wu Qiang, female, Ph.
D.
, mainly engaged in microbial fermentation and metabolic regulation, bioactive peptide preparation and efficacy activity analysis and other scientific research work, for the undergraduate students of the School of Food and Chemical Engineering, mainly taught "Food Machinery and Equipment", "Test Design and Statistics", "Food Biotechnology" and other courses, among which "Food Machinery and Equipment" was recognized as a first-class undergraduate course
in Hunan Province 。 He presided over one key R&D project of Hunan Provincial Science and Technology Department (2016NK2082), one outstanding youth project of Hunan Provincial Department of Education (19B505), and participated in 3 projects of the National Natural Science Foundation of China; As the first author, he has published more than 10 papers in important academic journals at home and abroad, such as Crit Rev Biotechnol, J Agric Food Chem, Chinese Journal of Food Science, etc.
, including 1 cover paper of the American Chemical Society Top journal, and reviewed for Crit Rev Food Sci, Food Chem, J Cell Mol Med, J Nutr Biochem and other journals; Applied/authorized 10 Chinese invention patents and 1 international invention patent
.
Corresponding author
Yu Yougui, male, second-level professor, master's tutor, won the honorary titles of Hunan Provincial Government Subsidy Expert and Excellent Teacher, Xiangxi Specially Appointed Expert, etc.
, and was employed as the standing director of Hunan Food Science and Technology Society, the director of Hunan Botanical Society, a member of the Chinese Society of Bioengineering, a special expert of Hunan Province Enterprise, a science and technology commissioner of Hunan Province, a scientific and technological talent of Shaoyang City "Three Districts", and an industrial expert
of Shaoyang City 。 In the past five years, he has presided over the research and development and industrialization of "comprehensive technology of ecological winemaking" and won the second prize of Hunan Science and Technology Progress Award, obtained 2 invention patents, and presided over 3 provincial scientific research projects; He has published 63 scientific research papers on winemaking technology, authored "New Technology of Ecological Winemaking" and co-edited "Overview of Chinese Wine", and won 3 third prizes of Hunan Province Teaching Achievement Award; Supervised 10 graduate students
.
Zhong Changqing, male, is the deputy chief physician of the Department of Cardiology of the First Affiliated Hospital of Hunan Normal University and Hunan Provincial People's Hospital.
Mainly engaged in hypertension, heart failure, arrhythmia and other cardiovascular disease pathogenesis and diagnosis and treatment research, presided over Hunan Provincial Natural Science Foundation, Hunan Provincial Health Commission Scientific Research Fund, Hunan Provincial Science and Technology Department Innovation Project and other 4 projects, published 5 representative papers, obtained 2 national invention patents, won the third prize of Hunan Province Health Science and Technology Achievement Award 1
.
Qiang Wua, Changqing Zhongb,*, Guirong Zengc, Xu Zhanga, Liping Xianga, Chang Wana, Yougui Yua,*
a College of Food and Chemical Engineering, Shaoyang University, Shaoyang 422000, China
b Department of Cardiovascular Medicine, Hunan Provincial People's Hospital, Changsha 410005, China
c Hunan Experimental Animal Center, Hunan Drug Safety Evaluation and Research Center, Liuyang 410331, China
*Corresponding author.
E-mail address: zchqfly@126.
com
yufly225@163.
com
In order to prepare angiotensin I-converting enzyme (ACE) inhibitory peptides, distilled spent grains of Chinese strong-flavor Baijiu were hydrolyzed by alcalase followed by papain under optimized conditions.
A superior ACE inhibitory peptide was separated and purified by ultrafiltration and high-performance liquid chromatography (HPLC), and its amino acid sequence was further identified as Gln-Gly-Val-Pro (QGVP) by electrospray mass spectrometry (ESI-MS).
QGVP formed 6 hydrogen bonds with the active site of ACE, which is responsible for reducing α-helix structure content of ACE causing subsequent inactivation.
Moreover, it showed no significant cytotoxicity toward human umbilical vein endothelial cells (HUVECs), and significantly induced phosphorylation of endothelial nitric oxide synthase ( p-eNOS) and decreased endothelin 1 (END1) expression in angiotensin I (Ang I)-treated HUVECs, demonstrating the potential antihypertensive effect.
The peptide QGVP hydrolyzed from distilled spent grain proteins of Chinese strong-flavor Baijiu was expected to be used as a food ingredient to prevent or co-treat hypertension with other chemical drugs.
WU Q, ZHONG C Q, ZENG G R, et al.
Identification and characterization of a novel tetrapeptide from enzymatic hydrolysates of Baijiu byproduct[J].
Food Science and Human Wellness, 2022, 11(6): 1641-1649.
DOI:10.
1016/j.
fshw.
2022.
06.
023.
Article compilation content is provided by the author
