Biochemistry

Penicillin group antibiotics are effective in combating infections caused by staphylococci, streptococci and other microorganisms. Taste peptides. The most important compounds of this group are sweet and bitter peptides. In the production of ice cream, creams, aspartame, which is a methyl ester of L-acn-aspartyl-L-phenylalanine, is used as sweeteners or flavor enhancers. Aspartame is 180 times sweeter than sucrose, however, with prolonged storage and heat treatment, sweetness decreases. The sweetener is contraindicated in patients with phenylketonuria. Peptides of bitter taste are formed during the breakdown of proteins in cheeses and milk with the participation of proteases of lactic acid bacteria. They are low molecular weight hydrophobic compounds containing from 2 to 8 amino acid residues. Many of the bitter peptides contain N- terminal cyclized glutamic acid. As the peptides are hydrolyzed, the bitter taste of such compounds usually disappears. Protective peptides. One of the most common protective compounds is tripeptide glutathione (y-glutamylcysteinylyl glycine). Glutathione is found in all animal tissues, plants, bacteria, however, its greatest amount is found in yeast and wheat germ. Entering into redox reactions, glutathione acts as a tread - protects free - SN groups from oxidation. It takes on the action of an oxidizing agent, thereby “ protecting ” proteins or, for example, ascorbic acid. Glutathione takes part in the transport of amino acids through cell membranes, neutralizes mercury compounds, aromatic hydrocarbons, peroxide compounds, prevents bone marrow diseases and the development of eye cataracts. The restored form of glutathione that is part of baker's yeast, especially stored for a long time, or flour from sprouted grain, lowers the elastic properties of gluten and affects the quality of wheat bread. The disaggregating effect of reduced glutathione on gluten proteins can occur both without breaking peptide bonds and breaking them. QUESTIONS AND TASKS: 1. What are proteins and what are their functions in the body? 2. List the properties of proteins. 3. What is the structural and functional significance of hydrophobic, acidic, basic, sulfhydryl groups in proteins? 4. Proteins were burned, after which iron was found in the mineralizate. What proteins does this element contain? 5. What classifications of amino acids do you know? 6. What are essential amino acids and what foods do they contain? 76