What are milk peptides, soy peptides, and glutathione used for?
Abstract: Small molecule peptides are a group of different peptides composed of 20 kinds of natural amino acids in different compositions and arrangements, ranging from dipeptides to complex linear and circular structures. They are multifunctional compounds derived from proteins.
Small molecule peptides have a variety of human metabolism and physiological regulation functions, especially some low peptides not only have better digestion and absorption properties than proteins, but also have physiological functions such as promoting immunity, regulating hormones, antibacterial, antiviral, lowering blood pressure and lowering blood lipids. , Food safety is extremely high, it is currently the most popular research topic in the food science and technology field and a functional factor with great development prospects.
Keywords: small molecule peptides, active peptides
01 Classification of small peptides
1. Divided by raw materials
Small molecule peptides are divided into milk peptides, soy peptides, corn borders, bovine bone marrow peptides, momordica peptides, pea peptides, livestock peptides, oyster peptides, earthworm protein peptides, aquatic peptides, silk protein peptides and complex peptides.
2. Divided by health care function
Small molecule peptides are classified according to their health care functions, including digestible and absorbable peptides, antibacterial peptides, morphine peptides, morphine antagonistic peptides, angiotensin-converting enzyme inhibitory peptides (referred to as ACEI peptides), cholesterol-inhibiting peptides, and mineral absorption-promoting peptides. The body’s defense function peptides, bitter peptides and hepatic encephalopathy prevention and treatment peptides, etc.
02 Functional properties of small peptides
1. Immune active peptides
The casein in human milk or cow’s milk contains biologically active peptides that stimulate immunity. Soy protein and rice protein can produce immunologically active peptides through enzymatic reactions, such as the octapeptide with the sequence GYPMYPLR derived from rice protein; derived from soybeans Trypsin hydrolysate of protein, sequence is HCQRPR hexapeptide; human immunoglobulin, sequence is QRPR and tetrapeptide of GQRP; casein derived from human milk or cow milk, sequence is GFL tripeptide and leukocyte ( Antibiotics) immunologically active peptides (such as interferon) have immunological activity. In addition to stimulating the phagocytic ability of macrophages, some peptides can also inhibit the growth of tumor cells.
2. Neuroactive peptides
Many neuroactive peptides are obtained by hydrolysis of milk, fish, soy and grain proteins. After the protein is enzymatically hydrolyzed, peptides with opioid activity are produced, which can relieve pain and regulate human emotions, breathing, pulse and body temperature.
Unlike ordinary analgesics, neuroactive peptides enter the human body through the digestive organs without any side effects. Therefore, such peptides can be used as additives and added to food to be processed into functional foods for consumption by specific groups of people.
3. Antihypertensive peptides
At present, hypertension is a common cardiovascular disease, which seriously affects human health. Hypertension is caused by the vasoconstriction caused by the hydrolysis of angiotensin I by angiotensin-converting enzyme (ACE) to obtain angiotensin II. Therefore, substances that can inhibit the activity of ACE have the function of lowering blood pressure.
There are angiotensin-converting enzyme inhibitors (ACEI) in the enzymatic hydrolysis products of many proteins. For example, there are several hypotensive peptides in the chymotrypsin hydrolysate of casein; the enzymatic hydrolysis products of a-zein , There are also several active peptides for lowering blood pressure. It has been reported that if the c-terminal amino acid is Pn> or aromatic amino acid, then this peptide has a strong inhibitory effect on angiotensin converting enzyme. It can be seen that angiotensin converting enzyme (ACE) inhibitors (ACEI, that is, antihypertensive peptide), achieve the blood pressure function by inhibiting the activity of ACE, and achieve the purpose of treating hypertension.
4. Antibacterial peptides
Antibacterial peptides are a class of peptides with antibacterial activity secreted by prokaryotes, plants or animals, and are an important class of natural preservatives. Some microorganisms can produce antibacterial peptides such as bacitracin, which mainly inhibit the growth of Gram-positive bacteria. Some animals and plants can also produce antibacterial peptides. For example, insects can quickly synthesize a large number of antibacterial peptides when stimulated by external microorganisms, which can quickly kill invading germs. At the same time, these peptides can also inhibit or kill viruses and protozoa. There are also some food proteins that can produce antimicrobial peptides after enzymatic hydrolysis.
Antimicrobial peptides have high thermal stability and are ideal preservatives during food processing. Studies have shown that there is a synergistic and synergistic effect between antibacterial peptides and immunologically active peptides, which can enhance the body’s ability to resist pathogenic microorganisms, so it is expected to be applied as a new antibacterial agent in the food and pharmaceutical industries.
5. Other active peptides
Other functional active peptides, including cholesterol-lowering peptides, mineral absorption-promoting peptides (CPPS), enzyme regulators (such as chymase peptides), hormone peptides such as growth hormone releasing factor (GRFS), albumin insulin potentiating peptides, Antibacterial peptides (such as nisin and rubber), anticancer peptides (such as tumor cell necrosis factor, cyclohexene), anti-AIDS peptides (such as GLQ protein), etc.
03 Several commonly used active peptides
1. Milk peptide
In the world, milk peptides were first used in milk powder with low antigenicity and hypoallergenic milk powder after being hydrolyzed by protease. Developed the second generation of highly hydrolyzed whey protein peptide mixture, containing 10-12 amino acid peptides and 40% -60% free amino acids; in the 1990s, developed a low-level hydrolyzed whey protein peptide mixture, Peptides composed of 10-15 amino acids and less than 20% free amino acids have improved biological potency.
Chinese biotech workers have adopted microbial fermentation control and high protein conversion to develop milk peptide products, in which ammonia nitrogen accounts for about 20% and peptide nitrogen accounts for about 80%.
2. Soy peptide
Soy peptide is a polypeptide mixture obtained by separating and refining soybean protein after acid or enzymatic hydrolysis. It is mainly composed of small molecule peptides composed of 3 to 6 amino acids, and contains a small amount of macromolecular peptides, free amino acids, sugars and inorganic Ingredients such as salt. The protein content of soybean peptide is about 85%, and its amino acid composition is the same as that of soybean protein.
Compared with soy protein, soy peptides have the physiological functions of high digestion and absorption rate, rapid energy supply, lower cholesterol, lower blood pressure and promote fat metabolism, as well as no beany taste, no protein denaturation, acidity and no precipitation, heating and non-coagulation, and easy soluble With good processing properties such as good water and fluidity, it is an excellent raw material for health food.
3. High F value oligopeptides
High F value oligopeptides are oligopeptides with high branched chains and low aromatic amino acids, which are prepared by proteolysis of animals and plants. They are represented by low phenylalanine oligopeptides and have unique physiological functions. The F value refers to the molar ratio of branched chain amino acids (BCAA) to aromatic amino acids (AAA).
High F value oligopeptides have the functions of eliminating or alleviating the symptoms of hepatic encephalopathy, improving liver function and improving the state of protein malnutrition and anti-fatigue in many patients. In addition to making medicines for treating liver diseases, they can also be widely used as liver protection and protection. Liver functional foods, protein nutritional foods and enteric nutrients for burns, surgical operations, sepsis and other high-paying patients and patients with digestive enzyme deficiency, as well as nutritional supplements for high-intensity workers and athletes.
4. Glutathione (GSH)
Glutathione is an active tripeptide formed by the condensation of glutamic acid, cysteine and glycine through peptide bonds. It is widely present in animal liver, blood, yeast and wheat germ. There are also a small amount in plant tissues such as various vegetables. distributed. Glutathione has a unique physiological function and is called a longevity factor and anti-aging factor.
Because the glutathione molecule has a specific 1-peptide bond, it has many important physiological functions in the human body, such as the synthesis of protein and ribonucleic acid, the transportation of oxygen and nutrients, the activity of endogenous enzymes, and the participation of three in the body. The shuttle acid cycle and sugar metabolism have anti-oxidation, anti-fatigue, anti-aging, elimination of excessive free radicals in the body, detoxification and liver protection, prevention of diabetes and cancer, etc., so it has become the representative of the body’s defense function peptides, and can also be used for sports nutrition Food and functional food additives, etc.
04 Application prospects of small molecule peptides
Modern life has brought people great convenience and enjoyment, but at the same time, it is also due to the accelerating pace of life, fierce competition for survival, great work pressure and modern communication tools, household appliances, modern medical testing equipment, and urban glass curtain walls. , Indoor decoration and computer radiation to the human body and other complex factors, especially the “richness disease” caused by bad living habits and modern diet structure.
Factors harm the human body and cause physiological dysfunction of the human body, which greatly weakens the body’s own ability to synthesize peptides of nutrients such as protein and amino acids, so that modern people must supplement synthetic peptides to exert activity and diversity in the human body. Make people’s life activities reach the best state. Therefore, the research of small molecule peptides has been highly valued by countries all over the world.
With the development of biotechnology, a large number of small molecule peptides have been discovered. The application of biotechnology can produce a large amount of biologically active peptides and apply them to food industry processing. At present, it has been used in food formulations, functional foods, food additives, medicines, cosmetics and non-polluted feed additives, and has developed a series of functional foods such as baby food, sports food and antihypertensive food. The research and development of small molecule peptides, as an emerging high-tech biotechnology field in the world, has great development potential and is a sunrise industry with great development market. At present, although China has made gratifying development in this area, there is still a certain gap compared with developed countries. Therefore, the research of biologically active peptides has a wider application prospect in China.