Serine and cysteine proteases (None universally standardized; common abbreviations include "SP" for serine protease and "CP" for cysteine protease in literature, but these are not official IUPAC abbreviations)

Serine proteases and cysteine proteases are large families of enzymes that function as hydrolases, catalyzing the cleavage of peptide bonds in proteins using a nucleophilic serine or cysteine residue in their active site[1][3][9]. Both have diverse biological roles, including digestion, blood clotting, immune processes, and tissue remodeling[7][3][2]. Serine proteases are characterized by a catalytic triad of serine, histidine, and aspartate; cysteine proteases feature a triad or dyad with cysteine as the nucleophile[9][3][10]. Dysregulation of either class is implicated in multiple diseases (cancer, neurodegeneration, infection, inflammatory disease), making them important therapeutic targets[1][2][3]. Numerous drugs target members of each class, mainly through active site inhibition. Due to broad functional diversity, "Serine and Cysteine Proteases" refers collectively to two large, structurally distinct, but functionally overlapping enzyme families[5].

Other names

Serine peptidaseCysteine peptidaseThiol protease (for cysteine protease)Endopeptidase (for many family members)

Competitive inhibition of the active catalytic site; Covalent modification of the nucleophilic residue (serine or cysteine); Blockade of substrate entry; Allosteric modulation