Primary Structure; the number, type and sequence of amino acids The primary level of structure in a protein is the linear sequence of amino acids, formed by a condensation reaction. The primary structure of these proteins are very different. The haemoglobin molecule consists of four polypeptide (globin) chains, where as collagen is made up of three polypeptide chains wound round each other. In Haemoglobin there are a wide range of amino acid constituents in the primary structure, in contrast 35% of collagen’s primary structure is glycine. This difference in primary structure causes the proteins themselves to be different; due to the original different primary structure the haemoglobin protein is soluble in water whereas the collagen protein is not.
Secondary structure; Formed when the chain of amino acid coils or folds to form an alpha helix or beta pleated sheet. Haemoglobin is comprised of four polypeptide subunits, two with alpha helix secondary structure and two with beta pleated sheet form. All four components carry a heme group that