Biochemistry

amino acid composition of plant and animal proteins allows you to increase their biological value when you consume the required amount of various protein foods. Only such food can be called full. 2.8 PROTEINS OF FOOD RAW MATERIALS Cereal proteins Comparing the amino acid composition of the proteins of cereal crops, the following is noted: all of them, with the exception of oats, are poor in lysine. In all cereal proteins except nee and sorghum, there is little isoleucine. Wheat, sorghum, barley and rye proteins are characterized by a small amount of methionine. Wheat proteins have little threonine. There are few tryptophans in maize proteins. The most balanced amino acid composition are proteins of oats, rye and rice. Soluble proteins such as albumin, globulin, protamine and glutelin are released from cereal proteins. In addition, insoluble proteins - scleroproteins are contained. They are located in the shells of the grains and in the peripheral layer. Albumins have a high content of lysine, threonine, methionine, isoleucine and tryptophan. Globulins are poorer in lysine, tryptophan and methionine. There are a lot of glutamic acid and proline in protamines. Glutelins by amino acid composition occupy an intermediate place between protamines and globulins. Proteins are unevenly distributed between the morphological parts of the grain. The main amount of proteins is contained in the endosperm, the smaller - in the aleurone layer and embryo. The proteins of the embryo and the aleuron layer are represented by albumin and globulin. They perform catalytic, enzymatic functions during the germination of grain. The endosperm contains albumin, protamine, and glutenin. Glutenins and protamines perform a reserve function, and albumin and globulins are part of membranes, ribosomes, mitochondria, and other cell organelles. In addition, they are part of complex proteins: nucleoproteins, lipoproteins and phosphoproteins. The composition of cereals also contains non-protein compounds involved in the formation of physico-chemical properties. In particular, wheat contains proteases, amylases, protein inhibitors. Using modem research methods, the structure of the gliadin fraction of wheat was established. It contains glutamine, glutamic acid, hydrophobic amino acid residues, albumin, globulins. Glutenin is also a part of wheat. It is built of polypeptide chains connected by disulfide bonds. 69