Biochemistry

aldehyde, pyridoxine is converted to pyridoxal (2-methyl-3-hydroxy-4-formyl- 5-hydroxymethylpyridine). When the hydroxy group in the fourth position is converted to the amino group, pyridoxamine (2-methyl-3-hydroxy-4- aminomethyl-5-hydroxymethylpyridine) is formed. Each of these substances has the properties of a vitamin, because in the body it can turn into pyridoxalphosphate, which is involved in chemical reactions associated with the activity of this vitamin. x° C< C -H Z OH HO-v C-CH,-O-P=O I !| 4 OH H5C-C > “ H N Pyridoxalphosphate Vitamin Вб is resistant to high temperatures. In a very acidic or sharply alkaline environment, it does not lose its biological properties even with autoclaving. It is rapidly destroyed in the light and during oxidation. Pyridoxine is readily soluble in water and ethanol, poorly in ether and chloroform. Biological role. Pyridoxine is a part of enzymes that catalyze protein metabolism, participates in decarboxylation reactions of a number of amino acids with the formation of biological amines (for example, decarboxylation of histidine to histamine, tryptophan to serotonin, etc.). Synthesis of vitamin PP from tryptophan and the conversion of cysteine to tuarin, as well as decarboxylation of cysteine with the formation of the mercaptoethylamine thiol compound, which is part of coenzyme A, takes place in participation of pyridoxalphosphate. These reactions are important especially for nervous activity, since these compounds are either mediators of the nervous system or serve as the basis for their formation. Vitamin B 6 is involved in the synthesis of hemoglobin, cytochromes, catalase, pyroxidase, in the conversion of linoleic acid to arachidonic acid, favorably affects the skin function. Pyridoxine deficiency. Vitamin B 6 deficiency under normal conditions is a rare occurrence. It expresses in irritability and lethargy, nausea, decreased appetite. The face skin and scalp becomes dry, flaky (seborrhea). Sometimes there arc cracked lips and sores in the mouth comers, inflammation of the tongue, conjunctivitis. 251