Protease Enzyme

The breakdown of proteins in your body is possible due to the protease enzyme. These enzymes use proteolytic action. They break the peptide bonds holding proteins together.

Almost all living organisms have these in their body. They include bacteria, plants, animals, fungi, and some viruses. The body is able to digest food and perform many other functions because of its action.

Types of Protease Enzymes

The way they cut (hydrolyse/cleave) proteins and where they do it becomes the deciding factor when it comes to their types. Mainly they are:

Exopeptidases cut peptide bonds at the ends of proteins. For example: aminopeptidases (N-terminal) and carboxypeptidases (C-terminal).
Endopeptidases cut bonds inside the protein chain. Some common examples are pepsin, trypsin, and chymotrypsin.

There are also oligopeptidases. These enzymes hydrolyse short peptides (usually 2–20 amino acids) in short proteins. Oligopeptidases hydrolyse short peptides (usually 2–20 amino acids) into smaller peptides or amino acids.

Types of Protease Based on pH

Protease enzymes work best at different pH levels:

Acid Proteases

Work in acidic places like the stomach
Example: Pepsin

Neutral Proteases

Work best at neutral pH (around 7)
Found in plants, bacteria, and in some animal tissues (e.g., pancreatic enzymes)

Alkaline Proteases

Work in slightly basic (pH 7.5–8.5) or alkaline areas, like the small intestine
Example: Trypsin, Chymotrypsin

Each type works in a different part of the body.

How Protease Enzymes Work

Proteases break proteins into smaller peptide bonds to produce smaller peptides. These further degrade into amino acids. These amino acids are then absorbed by the body and used for growth and repair.

Some proteases work on many proteins. Others are very specific and act on only one type. For example,

Trypsin is general (cleaves peptide bonds after lysine or arginine residues)
Thrombin is specific to blood clotting (cleaves fibrinogen to fibrin)

Proteases often start as inactive forms. These are called zymogens. They become active only when needed. This keeps the body safe from unwanted protein breakdown (in the pancreas or stomach).

Functions of Protease Enzymes

Protease enzymes help with many important processes in the body:

Breakdown proteins from food into amino acids.
Activate clotting factors to support blood clotting.
Aid in cell repair, growth, and prevent cell loss.
Boost immune defences against infections.
Remove and recycle damaged proteins effectively.
Facilitate healing of wounds and reduce muscle soreness.
Help manage inflammation and tumour development.

Examples of Protease Enzymes

Here are some common protease enzymes and what they do:

Protease Enzyme	Function
Pepsin	Breaks down proteins in the stomach
Trypsin	Works in the small intestine; breaks proteins into smaller pieces
Chymotrypsin	Breaks down proteins in the small intestine
Carboxypeptidase	Helps finish protein digestion
Dipeptidase	Breaks dipeptides into amino acids
Elastase	Digests a protein called elastin
Thrombin and Plasmin	Help with blood clotting
Collagenase	Breaks down collagen in tissues
Renin and Insulinase	Involved in hormone processing Renin regulates BP by cleaving angiotensinogen Insulinase breaks down insulin and other peptide hormones

Digestion of Proteins

Protein digestion starts in the stomach with pepsin. Pepsin comes from pepsinogen, which is activated by stomach acid. It breaks large proteins into smaller ones.

Next, in the small intestine, other proteases join in. These include trypsin and carboxypeptidase. They are made in the pancreas as inactive forms. An enzyme called enterokinase activates them. Chymotrypsin is activated by trypsin.

Finally, dipeptidase breaks small protein pieces into amino acids. These are absorbed by the body and used as needed.

Summary

Proteases are enzymes that break down proteins into amino acids. They aid digestion, boost immunity, and assist healing. Proteases are found in all living beings and work best at specific pH levels. Some act inside proteins, others at the ends. Most start inactive and only become active when the body needs them.