: Glycoprotein is a conjugated protein formed by the combination of a protein with carbohydrate side chains. Certain enzymes, antigens and hormones are glycoproteins. Gelatin is a derived protein obtained by the hydrolysis of collagen present in the connective tissue of skin, bones and joints. Casein (phosphoprotein) is the principal protein of milk. When rennin or pepsin acts on casein, paracasein is formed. Haemoglobin (chromoprotein) contains globulin with iron in ferrous state. Egg albumin is a simple protein.