Angiotensin converting enzyme (ACE) can raise blood pressure through the renin-angiotensin system, which alters kidney function. The enzyme is zinc dependent. ACE can hydrolyze and inactivate a nine amino acid blood vessel dilator, bradykinin. Loss of the blood vessel dilation from bradykinin causes some high blood pressure.
ACE inhibition can successfully treat hypertension and heart failure. There are dietary short chain peptides which have ACE inhibitor activity. They can be released from proteins through commercial processing or through gastrointestinal digestion and bacterial digestion. Such ‘bioactive peptides’ make measureable biologic changes and improve human health.
Bioactive substances are chains of 3-10 amino acids. They must be released from the parent protein and become active. They can be released by processing and by enzymes, such as protease, chymotrypsin, and trypsin. The branch of food science that studies peptides is food peptidomics.
Different biologic activities of these peptides depend upon the amino acid sequences. Some of the activities are opium-like, mineral binding, immunomodulatory, antioxidant, antithrombotic, hypocholesterolemic, and anti-hypertensive. Such activity is found in milk proteins, such as casein, lactalbumin, beta-lactaglobulin, and lactoferrin. Whey proteins contain similar activity. Foods containing such peptides are called functional foods.
ACE inhibitors have been found in the following: maize, wheat, rapeseed (canola,) soybean, buckwheat, sunflower, sorghum, milk, cheese, meat, eggs, and fish. Bioactive peptides derived from garlic (Allium sativum) can lower blood pressure.
Peptides can be flavorful or bitter. Peptides can be larger, up to 51 amino acids. These longer chains can be absorbed through the intestinal wall and are bioactive. The peptide activity is reduced in longer chains. Shorter chain di- and tri-peptides are absorbed more rapidly than free amino acids.
Commercially, acid hydrolysis or enzymatic digestion can release peptides. The enzymatic method is more satisfactory and easier to control. Microbial fermentation produces peptides. Lactic acid bacteria and Bifidobacteria are most commonly used.
Nitric oxide can, also, inhibit ACE.
CONCLUSION: Biologically active peptides can be absorbed through the intestine and are biologically active in the body. Short chain peptides, produced by enzymatic and bacterial processes, can act as ACE inhibitors and can lower blood pressures.
NOTE: Arginine amino acid supplements release nitric oxide in the body to dilate blood vessels and increase circulation.
Hydrolysis is a chemical process in which a substance is combined with water. The water is split into a hydrogen ion and a hydroxide ion. Each of the ions combines with half of the parent chemical. This is one way of breaking down peptides.