Question

Describe the role of various enzymes in the digestion of proteins in our alimentary canal

Answer 1

Well there are number of enzymes involves in the digestion of protein Important one are below
All the enzymes which act on the protein are named as the proteases 
In the stomach pepsin is activated  which converts protein in to the proteoses and peptides .
In the small intestine trypsin enzyme is activated with the help of entrokinase and this trypsin activated the enzyme Chymotrypsin which directly act on protein and convert it into the peptides.
Then these peptides are converted in to amino acids and smaller peptides chains with the help of enzyme "Carboxypeptidases" 

Answer 2

The digestion of proteins start in the stomach and gets completed in the small intestine. These enzymes that act on proteins are known as proteases.

The digestive juice secreted in the gastric glands present on the stomach walls is called gastric juice. The main components of gastric juice are HCl, pepsinogen, and rennin. The food that enters the stomach becomes acidic on mixing with this gastric juice. The acidic medium converts inactive pepsinogen into active pepsin. The active pepsin then converts proteins into proteases and peptides.

Proteins (in the presence of Pepsin) → Proteoses + Peptides

The enzyme rennin plays an important role in the coagulation of milk.

In the small intestine, the food from the stomach is acted upon by three juices present in the small intestine – pancreatic juice and intestinal juice (known as succus entericus).

Pancreatic juice contains a variety of inactive enzymes such as trypsinogen, chymotrypsinogen, and carboxypeptidases. The enzymes are present in an inactivated state. The enzyme enterokinase secreted by the intestinal mucosa activates trypsinogen into trypsin.

Trypsinogen (in the presence of Enterokinase) → Trypsin + Inactive peptide

Chymotrypsinogen (in the presence of Trypsin) → Chymotrypsin

Proteins (in the presence of Chymotrypsin) → Peptides.

Peptides (Carboxypeptidase) → Smaller peptide chain + Amino acids.

Bile juice has bile salts such as bilirubin and biliverdin which break down large, fat globules into smaller globules so that pancreatic enzymes can easily act on them. This process is known as emulsification of fats. Bile juice also makes the medium alkaline and activates lipase. Lipase then breaks down fats into diglycerides and monoglycerides.

Intestinal juice contains a variety of enzymes. Pancreatic amylase digests polysaccharides into disaccharides. 

Peptides (in the presence of dipeptidases) →  Amino acids.

Pancreatic lipase breaks down fats into diglycerides and monoglycerides and the nucleases break down nucleic acids into nucleotides and nucleosides.