Question

As we are having pepsin which helps in the digestion of proteins then why do pepsin itself do not also break milk protein into peptides and peptones?

Answer 1

Dear Student,

The stomach of infants secretes a proteolytic protein known as rennin which causes the coagulation of milk and converted the milk casein into paracasein so that pepsin can act upon it. This enzyme, rennin, is absent in the stomach of adults. Therefore, pepsin can not act upon it and break milk protein into peptides and peptones.
Each enzyme acts upon a specific type of food and some enzymes act only when the composition of food is altered by some other protein.

Regards