Cysteïnprotease

Cysteïnprotease is a type of enzyme that catalyzes the breakdown of proteins. Its defining characteristic is the presence of a cysteine residue in its active site, which plays a crucial role in the catalytic mechanism. These enzymes are also known as thiol proteases due to the sulfhydryl group (-SH) of the cysteine residue.

Cysteïnproteases are involved in a wide range of biological processes. In unicellular organisms, they are essential for nutrient acquisition and protein turnover. In multicellular organisms, they play vital roles in processes such as programmed cell death (apoptosis), immune response, blood coagulation, muscle contraction, and the processing of proteins.

The catalytic mechanism of cysteïnproteases typically involves a catalytic dyad or triad, where cysteine works in conjunction with other amino acid residues, often histidine and sometimes aspartate. This triad facilitates a nucleophilic attack on the peptide bond of the substrate, leading to its hydrolysis.

Dysregulation of cysteïnprotease activity has been implicated in various diseases, including cancer, viral infections, inflammatory disorders, and neurodegenerative diseases. Consequently, cysteïnproteases are significant targets for drug development, with inhibitors being explored for therapeutic interventions in these conditions. Examples of well-studied cysteïnproteases include caspases, cathepsins, and papain.