The basic structure common to all proteins is the peptide linkage which is formed by condensation the carboxyl group of one of amino acid with the amino group of another.
In this way chains are created, which contains only 3 amino acids, to complex polymers of 1000 or more. At physiological temperatures in aqueous solution, the polypeptide chains of proteins fold into a form that in most cases is globular.
The sequence in which amino acids are arranged in the peptide chain is known as the primary structure of the molecule. In biochemistry, this is always given starting with the N-terminal and ending with the C-terminal amino acid, because this is the order in which amino acids are added during protein synthesis in the cells.
The amino acid chain is the primary and central component of the protein, but not necessarily the only component. Some protein may include other atoms or small molecules which are required for their function and. or stability. The proper sequence of amino acids tends to be a critical factor in protein function.
Protein molecules serve as some of the major structural elements of living system. This function depends on specific association of protein subunits with themselves as well as with other proteins, carbohydrates and so on, enabling even complex systems like actin fibril to assemble spontaneously.
Structure of protein
