Biochemistry

to regulate water balance, osmotic pressure in the blood and stimulate the processes of memorization. The hypothalamic hormones, in which the endocrine system interacts with the higher parts of the central nervous system, are low molecular weight peptides. Hypothalamic hormones are involved in the release of hormones from the anterior pituitary gland. Many of the hormones (oxytocin, thyroliberin, prolactin - the hormone of the anterior pituitary gland and gonadoliberin - the hormone of the hypothalamus) are present in the milk of ruminants and nursing mothers. Known peptide hormone melanotropin (MSH), secreted into the blood by the intermediate pituitary gland. Single-chain peptide stimulates the formation of pigment, causing the color of the eyes, skin, hair. Neuropeptides. In recent years, more than 50 peptides contained in the brain of humans and animals have been isolated into a separate group. These substances determine behavioral reactions (fear, fear), affect the processes of memorization, learning, regulate sleep, and relieve pain. Neuropeptides called endorphins and enkephalins. Vasoactive peptides. The group of peptides that affect vascular tone (vasoactive) include bradykinin, collidine and angiotensin. The first peptide contains 9 amino acid residues, the second 10, and the third 8. Peptide toxins. The peptide nature has a number of toxins produced by microorganisms, poisonous mushrooms, bees, snakes, sea mollusks and scorpions . 5 enterotoxins produced by the bacteria Staphylococcus aureus (А, В, C, D and E) and 7 neurotoxins (A to G) produced by Clostridium botulinum have been identified. Toxins can cause food poisoning when consuming dairy, meat, fish, liquid egg products, as well as salads and cream fillings, flour confectionery products, provided that the rules of sanitary-hygienic processing and storage of the latter are not observed. Botulinum toxins are among the most potent poisons and often cause fatal food poisoning when vegetables, fish, fruits and seasonings are not properly processed. Enterotoxins can also be produced by the bacteria Salmonella and Clostridium perfringens, causing a disorder of the intestines, fainting conditions and fever (typhoid fever). Enterotoxins are produced more often in products of animal origin (beef, poultry, cheese, fish) than vegetable (beans, olives). Peptides are antibiotics. Representatives of this group of peptides are gramicidin-S, a cyclic antibiotic synthesized by Bacillus brevis bacteria, and surfactin, a surface-active (containing ester bond) antibiotic synthesized by Bacillus subtilius bacteria. Both antibiotics are effective in combating infectious diseases caused by streptococci and pneumococci. The structural basis of antibiotics secreted by Penicillium molds is a dipeptide built from the residues of D-valine and cystine. 75