Peptidase

The peptidases or proteases are enzymes that break the peptide bonds of proteins. To do this, they use a water molecule (through hydrolysis), which is why they are classified as hydrolases.

Features

Proteases are present in all living beings in which they participate both in the hydrolysis of unwanted proteins as well as in the regulation of different physiological processes. These enzymes are classified into:

Substrate specific

Proteases are capable of breaking specific peptide bonds of their target protein. This limited proteolysis produces peptides and is unable to reduce these to their constituent amino acids.

Substrate nonspecific

Yes, they can reduce a complete peptide to amino acids (unlimited proteolysis).

Inhibition

The function of peptidases is inhibited by protease inhibitors. Natural protease inhibitors should not be confused with the protease inhibitors used in antiretroviral therapy. Some viruses, including HIV, depend on proteases in their reproductive cycles, which is why protease inhibitors are being developed as antiviral methods.

Since peptidases are themselves peptides, it is natural to wonder if peptidases can be degraded. It is a known fact that many peptidases are self-replicating. This may be an important method of regulating the activity of peptidases.

Classification of peptidases

Peptidases -according to the MEROPS database- are classified according to the similarities of their three-dimensional structure. These include the Clan that contain all peptidases that have originated from the same common ancestor of peptidases. If the three-dimensional structure is not available, the classification is made based on the order of the catalytic residues in the peptide chain and the sequences that flank them.

• Serina peptidasas
• Treonina peptidasas
• Cisteina peptidasas
• Aspartil peptidasas
• Metalopeptidasas
• Glutamil peptidasas
• Mixed with a catalytic type (Serin, Cistein, Treonin)

A Clan is formed by different Families of proteases which group homologous peptidases in their amino acid sequence. Threonin and glutamyl peptidases were not described until 1995 and 2004, respectively. The mechanism of action of proteases consists of the hydrolysis of a peptide bond using the amino acids Serine, Cysteine and Threonine as a nucleophilic molecule (in serine, cysteine and threonine proteases) or a water molecule (in aspartyl, metallo- and threonine proteases). glutamyl peptidases) which attack the carbonyl group of the peptide bond of the target protein (Figure 1).

Figure 1. Mechanism of action of different types of proteases

Function

Peptidases are present in all organisms and constitute 1-5% of the genome content. These enzymes are involved in a large number of physiological reactions from the simple digestion of food proteins to highly regulated cascades (eg, the blood coagulation cascade, the complement system, apoptosis pathways, and the cascade that activates Prophenoloxidase). of the invertebrate). They can break all proteins unless they are part of a living cell.

Uses

In the baking industry they are used as bread improvers.