Proteases are enzymes which hydrolyze the peptide bonds established between two amino acids of a polypeptide chain (peptides and proteins). Proteases are classified into 6 groups – aspartate-, cysteine-, glutamate-, metallo-, serine- and threonine-proteases – and the exo- and endopeptidases differ according to their mode of action. These enzymes can also be categorized according to the pH at which their optimal activity, and this is referred to as acid, neutral or alkaline proteases.

The determination of the activity of the proteases is carried out according to an internal method based on the hydrolysis of a model substrate in peptide fragments soluble in trichloroacetic acid (TCA).