Many amino acids are linked by peptide bonds to form proteins. 20 types of amino acids participate in the formation of proteins. Amino acids join together to form polypeptide chains. Polypeptides are the basic building blocks of proteins. One or more polypeptide chains join together to form a protein. Proteins are called polypeptide compounds because they contain peptide bonds. A polypeptide chain consists of at least 50 amino acids. The small protein insulin is made up of 51 amino acids and the large protein titin is made up of 40,000 amino acids. Albumin protein contains 582 amino acids.
Lysozyme is a protein made up of a polypeptide.
Proteins made up of two polypeptides are integrins.
Collagen is a protein made up of three polypeptides.
Hemoglobin is a protein made up of four polypeptides.
There are four types of protein structure. These are-
1. Primary structure: The primary structure of protein is chain shaped. Insulin is the primary protein.
2. Secondary structure: The secondary structure of protein is coiling and folding. It consists of α-helix and β-pleated chains. Silk and keratin proteins are secondary structures.
3. Tertiary structure: Tertiary structure of protein is three dimensional. Fibrinogen protein is of tertiary structure.
4. Quaternary structure: Two or more polypeptide chains joined by disulfate or hydrogen bonds to form a protein is called quaternary structure. It is a quaternary structure. Hemoglobin is quaternary protein.