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.