Biochemistry

The fractional composition of grain proteins determines the technological properties of wheat, rye, com, oat flour and various cereals. Wheat proteins swell well and form a cohesive elastic mass - gluten, the main part of which is gliadin and glutenin. A less elastic, albeit cohesive mass is obtained from barley proteins. The protein substances of com, oats, rice, buckwheat swell weakly and are not able to form a viscous dough. Protamines. These are low molecular weight proteins (molecular weight up to 12,000 Da), containing up to 80% of basic amino acids, mainly arginine. Consequently, protamines have pronounced basic properties and are soluble in weak acids. The molecules of these proteins are a polyvalent cation and easily react with negatively charged substances, such as nucleic acids. Protamines are widely distributed in nature, especially in the germ cells of fish, mammals, and humans. Protamines form a strong complex with DNA molecules and thus protect them from adverse effects. Histones. Proteins with a low molecular weight (12000-24000 Da) and pronounced basic properties. They soluble in weak acids. Histones are present mainly in the nuclei of plant and animal cells. Their main functions are structural and regulatory. Histones have a large positive charge, which allows them to electrostatically interact with DNA and stabilize its structure. The regulatory function of histones is their ability to block the transfer of genetic information from DNA to RNA. Proteinoids. Slightly soluble fibrillar proteins of supporting tissues (bones, cartilage, ligaments, tendons, hair, etc.). They are characterized by a high sulfur content. Proteinoids include: fibroin - silk protein; keratins - proteins of hair, horns, hooves; collagens are proteins of connective tissues. Complex proteins Complex proteins can be considered as molecular complexes of two substances. The non-protein part (prosthetic group) is firmly connected to the protein by covalent or non-covalent bonds, therefore, such complexes function as a whole. Lipoproteins. The prosthetic group in these proteins is represented by lipids (free fatty acids, triglycerols, phospholipids, cholesterides) . Lipoproteins are widespread in nature. They are found in all cell membranes, blood plasma, brain, milk, eggs, etc. Free lipoproteins (not included in biomembranes) perform a transport function. Due to the presence of polar hydrophilic groups, they are soluble in the aquatic environment and are able to transfer lipids entering the blood to various organs and tissues of the body. 64