Antifreeze proteins (AFPs) are specific proteins, peptides, and glycopeptides made by different organisms to allow cells to survive in sub-zero conditions. AFPs, or ice structuring proteins, refer to a class of polypeptides produced by certain plants, animals, bacteria, and fungi that permit their survival in temperatures below the freezing point of water. They are present in many fish and invertebrates as well as plants to prevent them from freezing in cold weather or cold water. Antifreeze proteins can bind to the ice by the phenomenon of adsorption and inhibit the growth of ice crystals. Owing to this property, antifreeze proteins are widely used in various end-use industries, such as agricultural, cosmetics, medical, and food & beverage.
In the food and beverage industry, AFPs help prevent freezing-thawing damage to food products, maintain the shelf life of frozen meat, fish, and flour dough, and enhance the texture of ice cream. While in the medical industry, they are used in cryosurgery procedures, cell cryopreservation, and to coat medical devices, such as catheters. These proteins are widely applied for research, food technology, and genetic engineering as well as being used in the automotive industry for the prevention of engine blocks from freezing. The importance of these proteins is manifold as they are extremely important in ensuring that the machinery, tools, and other essential elements are working properly and in time.
The main task of the refrigerator is to keep the temperature balanced so that there is no worry about the machinery or tools getting damaged due to sudden temperature changes. Thus, the antifreeze proteins must reach the instruments and other essential items before they stop functioning. This is to ensure that the objects are kept at the right temperature without causing any damage or malfunctioning. Antifreeze proteins are produced by certain plants, animals, bacteria, and fungi which allow their survival in low temperatures below the normal freezing point of water. These can sometimes be produced naturally in water bodies, although the activity level in water bodies is usually very low due to the stringent measures that are being followed to prevent the growth and spread of bacteria and fungi.
The reaction of peptide chains with water results in information of a particular crystal structure known as antifreeze. Most commonly the type of antifreeze which is made from the glycerol family is produced from a variety of marine mollusks such as shrimp, lobsters, and crabs. It is taken from the fossilized tissue of these animals and used as a source of food and medicine. This was the only source of marine antifreeze up until very recently as other sources such as petroleum products and gasoline were discovered. Now, however, a wide range of chemical compounds including synthetic antifreeze has been developed with the aid of modern science and medical research.
Antifreeze proteins are produced by various organisms such as bacteria, insects, plants, fishes, nematodes, diatoms, and others. They work on the principle of adsorption in which they bind to the ice-forming surface and stop the formation of ice crystals. Thus, antifreeze proteins have a wide range of industrial applications.