The selectivity of peptidases

The hydrolysis products of proteins are absorbed in the digestive tract mainly in the form of free amino acids, with the assistance of carrier proteins. Amino acids, like glucose, are absorbed by ions with Na ^+.

The absorption of small peptides is proved. Oligopeptides are hydrolyzed after absorption. In some cases, large peptides, such as botulism toxin, cholera and diphtheria are absorbed. Diphtheria toxin consists of two polypeptides. Transport of the two polypeptides, or a toxin through the lipid bilayer of biomembranes hitherto is considered unique and mysterious process.

Absorbed amino acids enter the portal vein to the liver. In the liver, the amino acids are involved in the synthesis of proteins, nucleotides, creatine, etc. Much of the amino acid is carried by the blood throughout the body and used for physiological purposes.

The parenteral protein nutrition leads to the development of sensitization, and the re-introduction of proteins can cause anaphylaxis. Hydrolysates of proteins (a mixture of amino acids) are used for protein nutrition. It does not cause allergic reactions. However, side effects are possible, such as disruption of mental (psychological) activity.

Amino acids metabolism

Conversion of amino acids under the action of intestinal microflora

All the conversions of amino acids caused by the activity of intestinal microorganisms were called "putrefaction of proteins in the intestine". Toxic metabolic products as hydrogen sulfide H₂S, methyl mercaptane CH₃SH, amines, cresol, phenol, skatole and indole are formed in the large intestine.

In the liver they undergo neutralization by chemical binding with sulfuric or glucuronic acid and are excreted in the urine.

Date: 2016-04-22; view: 795