Function of Rennin Enzyme

Function of Rennin Enzyme

Rennin is an enzyme that is essential for the digestion of proteins. It helps digest milk in young mammals. This Buzzle article lists out the function of rennin enzyme.
Enzymes are organic catalysts that are produced in the body of all living organisms. The human body produces several enzymes that carry out or accelerate a number of chemical reactions in the body. Enzymes help maintain biochemical energy, and are necessary for regulating many vital body processes such as metabolism, respiration, digestion, blood clotting, coagulation, reproduction, and the process of growth and development. Rennin, which is also called chymosin or rennet, belongs to the aspartic proteinases family of enzymes. It is produced in the stomach of young mammals. This enzyme is essential for the digestion of mother's milk in young mammals.

Function of Rennin

Rennin is a coagulating enzyme produced in the inner lining of the abomasum (the fourth/true stomach) of the milk-fed calf. It is also produced in the stomach of a goat or a lamb. Some alternative sources of chymosin are plants, especially thistles and nettles, and microbes like fungi and yeasts. Being a proteolytic enzyme, the major function of rennin is to curdle milk. Rennin is produced in large amounts, immediately after the birth. Its production gradually decreases, and it is replaced by a digestive enzyme called pepsin.

Rennet is known to play an important role in coagulation and curdling of milk. Curdling of milk is essential for the proper digestion of milk proteins in the stomach. If milk is removed immediately from the stomach in its undigested state, then young mammals would not benefit from the milk proteins. Coagulation of milk by rennet allows it to remain for a longer time in the stomach.

So, how does rennin cause curdling of milk? Rennin is produced in the form of inactive prorennin. After consumption of milk, the hydrochloric acid in the gastric juice present in the stomach activates prorennin, and converts it into its active form, rennin. A caseinogen enzyme is present in the milk, which has four types of molecules. Rennin precipitates three of them, namely alpha-s1, alpha-s2 casein, and beta casein, in the presence of calcium in the milk. Kappa casein, which is the fourth molecule in the caseinogen enzyme, is not precipitated by calcium. Kappa casein is known to prevent the precipitation of alpha and beta caseins. Since coagulation is necessary, rennin enzyme inactivates kappa casein. In this way, milk is coagulated and properly digested.

The optimum temperature required for the reaction of milk and rennin is 37°C. At higher temperatures, the rennin enzyme molecules break down, and the action of rennin on milk ceases. If the temperature falls, it slows down the rate of reaction.

Due to its coagulating action on milk, rennin enzyme is commonly used in the food industry. It is widely used for the production of cheese. Rennin that is required for the production of cheese was earlier obtained mainly from the calf's stomach and other non-animal sources. However, for the industrial cheese production, a large amount of rennin is required. These days, genetic engineering methods are used for obtaining large amounts of rennin enzyme that is needed in the food industry.