Biochemistry

The primary structure of the protein. The primary structure represents as the number and sequence of amino acid residues in the polypeptide chain (Fig. 2.2). It is determined by: 1) the nature of the amino acids included in the protein; 2) the amount of each amino acid; 3) a strictly defined amino acid sequence of the polypeptide chain. Non-protein (prosthetic) groups are also included in the primary protein structure. The main type of chemical bond of the primary structure is the peptide bond. A number ofproteins have a small number of disulfide bonds. Each protein is characterized by a unique primary structure determined by the genetic level. It has now been established that the biological activity of a protein and its general conformation are determined by the amino acid sequence. Substitution of an amino acid in a polypeptide chain can lead to both structural changes in a protein molecule and changes in its physicochemical properties and biological functions. Figure 2.2 - The primary structure of ribonuclease 53