Cysteine protease

Cysteine protease is a type of protease containing a cysteine residue that is essential to its catalytic function. This class of enzymes is involved in numerous physiological and pathological processes.

Function

Cysteine proteases have the ability to break down proteins in response to signals. They are involved in numerous physiological processes, including immune response, cell death, and protein degradation. They are also implicated in pathological processes such as cancer, inflammation, and infectious diseases.

Structure

Cysteine proteases are characterized by the presence of a cysteine residue in their active site. This cysteine acts as a nucleophile and forms a covalent intermediate with the substrate during catalysis. The structure of cysteine proteases is highly conserved, with a common fold and catalytic triad or dyad.

Classification

Cysteine proteases are classified into clans and families. Clans are groups of families for which there is evidence of common ancestry. Each clan is identified with two letters, the first representing the catalytic type of the families included in the clan, with "C" for a cysteine protease family. Families are grouped by their catalytic type, the order of the catalytic residues in the protein sequence and by their protein fold.

Examples

Examples of cysteine proteases include caspases, which play a key role in apoptosis, or programmed cell death. Cathepsins are another type of cysteine protease and are involved in protein degradation in the lysosome.

See also

• Protease
• Cysteine
• Caspase
• Cathepsin

References

• Papain enzyme
  Papain enzyme
• 
  Cystein protease reaction mechanism