How Does Proteases Degrade Proteins?
Proteases (proteinases, peptidases, or proteolytic enzymes) are enzymes that break peptide bonds between amino acids of proteins. The process is called peptide cleavage, a common mechanism of activation or inactivation of enzymes, especially those involved in blood coagulation or digestion. They use a molecule of water for this and are thus classified as hydrolases. There are currently six classes of proteases: Serine proteases Threonine proteases Cysteine proteases Aspartic acid proteases (e. g., plasmepsin) Metalloproteases Glutamic acid proteases the threonine and glutamic acid proteases were not described until 1995 and 2004, respectively. The mechanism used to cleave a peptide bond involves making an amino acid residue that has the character of a polarized peptide bond (serine, cysteine and threonine peptidases) or a water molecule (aspartic acid, metallo- and glutamic acid peptidases) nucleophilic so that it can attack the peptide carbonyl group. One way to make a nucleophile is
