Question

Casein is converted to caseinogen in the presence of ?

Answer 1

Hint: Casein is a milk protein generally found in mammalian milk. When a newborn consumes milk, the casein present in it gets broken down by the enzymatic action of Renin, secreted in the stomach. This whole process is known as the curdling of milk.

Complete answer:
Renin is a protein degrading enzyme secreted along with the gastric juice in the stomach. Renin, also known as Chymosin, is a very important enzyme for infants, when it comes to the digestion of milk. It is responsible for the coagulation of milk in infants.
Another important factor in this process is the presence of calcium ions. Renin in the presence of calcium ion changes milk casein (soluble) to paracasein (insoluble). This process is further carried forward by the calcium ion which converts paracasein to Calcium paracaseinate converts Calcium paracaseinate to Peptones.

This entire process is known as the Curdling of milk.
Pepsin performs the same function in adults that Renin has in infants, as Renin is absent in adults. This same process is performed by Chymotrypsinogen in the small intestine, by hydrolyzing casein to paracasein resulting in coagulation with the help of calcium. Therefore, Casein is converted to caseinogens by Renin in the presence of Calcium ions.

Note:
Curdling of milk is a very complex process. Renin is the main enzyme in this process but it has several other functions to perform as well. Renin is secreted by the kidney which regulates the blood pressure and water balance of the body. This whole process is known as Renin-Angiotensin-Aldosterone System or RAAS.