Proteins are found to have two different types of secondary structures viz. α - helix and ß -pleated sheet structure. α Helix structure of protein is established by

α-helix is one of the most common ways in which a polypeptide chain exists and forms all possible hydrogen bonds by twisting into a right-handed screw (helix) with the −NH group of each amino acid residue hydrogen-bonded to the C=O of an adjacent turn of helix.