What are the Nature and Actions of Pancreatic Enzymes?– Answered!

1. Trypsin:

This enzyme is secreted as the inactive proenzyme trypsinogen. This is rapidly activated into trypsin by the enzyme enteropeptidase (formerly called enterokinase) secreted into the intes­tinal lumen by the duodenal mucosa.

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Enteropeptidase in its function can be regarded as a proteolytic enzyme. It liberates a terminal hexa- peptide of the trypsinogen and thereby converting it to the enzymati- cally active trypsin.

Trypsinogen can also be activated in the same way as trypsin. This type of activation is called autocatalytic.

It is the most effective proteolytic enzyme which acts upon all iroteins that are attacked by pepsin. It acts more rapidly and comp- etely if the proteins have been partly hydrolyzed by pepsin.

Trypsin acting on native proteins causes them to pass through several intermediate stages such as globulins, alkaline metaproteins, leuteroproteoses, peptones, polypeptides and finally converting them into mono-amino acids (as leucine, aspartic acid) and diamino acids as lysine and arginine, etc.).

2. Chymotrypsin:

It is another proteolytic enzyme secreted s inactive proenzyme called chymotrypsinogen.

It is activated by trypsin to form the active chymotrypsin.

It acts in very much the same way as trypsin but in addition it assesses the power of clotting milk.

It completes the protein digestion at an optimum pH of 7—8. It behaves like gastric reman and gests casein of milk and gelatin.

3. Carboxypeptidase:

It is probably another proteolytic enzyme of pancreatic juice and is activated by trypsin and enterokinase.

It hydrolyses the amino acids, one by one from the end of a polypeptide chain which has a free carboxyl group. It does not generally attack dipeptides.

Two different carboxypeptidases of pancreatic juice named A and B have been described. The two differ in specificity depending on whether the free a carboxyl group is on a terminal aromatic or basic amino acid.

4. Pancreopeptidase E or Elastase:

It is capable of solubilizing elastin by hydrolysis of peptic bonds, essentially those adjacent to neutral amino acid residue.

5. Amylopsin or Amylase:

It is the most important starch splitting enzyme which converts starch, dextrin and glycogen into maltose. It requires the presence of chloride and phosphate as coen­zyme and acts best at pH 7′ 0.

6. Lipase or Steapsin:

This is most important fat-splitting enzyme of pancreatic juice.

It is secreted into the pancreatic juice in its active form. It has not yet been obtained in crystalline form but highly purified fractions have recently been prepared.

It rapidly acts on mixture of glycerides and fatty acids at a pH of 7—8. The fatty acids combine with alkali to form soap. It is essen­tial for absorption.

7. Sucrase:

It acts best at a pH of 5—7 and digests the sucrose into glucose and fructose.

8. Maltase:

It converts maltose into glucose at optimum pH 7-0.

Maltose+ H2O—-> Maltase — > Glucose

9. Lactase:

It reacts with lactose converting it into glucose and galactose. It acts best at, pH of 5 4—6 0.

Lactose + H₂O——- Lactase —- > Glucose + Galactose

10. Ribonuclease and deoxyribonuclease:

They split nucleic acids (of ribose and deoxyribose type respectively) into simple nucleo­tides.