What does caspase mean?
A caspase is one of a family of enzymes found inside animal cells that act as key agents of programmed cell death, or apoptosis. The name is a contraction of 'cysteine-dependent aspartate-directed protease', describing how the enzyme uses a cysteine residue to cut its target proteins specifically after aspartic acid. Caspases exist in cells as inactive precursors and are activated in a regulated sequence known as the caspase cascade: once triggered, they dismantle the cell's structural and regulatory machinery in an orderly fashion. Some members, such as caspase-1, also participate in inflammatory responses rather than cell death. Caspases are numbered according to the order of their discovery and grouped as initiators or executioners depending on their position in the pathway. Because defective apoptosis underlies diseases ranging from cancer to neurodegeneration, caspases are important targets of biomedical research and drug development.
nounAny of a family of intracellular cysteine protease enzymes that play essential roles in programmed cell death (apoptosis) and inflammation by cleaving proteins at specific aspartic acid residues.
- A member of the family of cysteine-aspartic proteases that mediate apoptosis.
- More broadly, any of these enzymes when involved in inflammatory signalling (e.g. caspase-1 in processing interleukins).
"The release of cytochrome c from the mitochondria triggers the activation of caspase-9, setting off the apoptotic cascade."
"Researchers found that inhibiting caspase activity delayed cell death in the treated neurons."
"Caspase-1 cleaves pro-interleukin-1β into its active form, linking inflammation to innate immunity."
Regular plural; typically refers collectively to the members of the caspase family or to multiple instances of a given caspase.
"Both initiator and executioner caspases are required for orderly apoptosis."
Named by fusing 'cysteine' and 'aspartate' with '-ase', the caspase is literally the executioner inside your cells — without it, apoptosis fails and cancer can take hold.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of caspase
The word 'caspase' was coined in the 1990s by researchers studying apoptosis, blending 'cysteine' and 'aspartate' with the standard enzyme suffix '-ase'. It reflects the enzyme's defining biochemistry — a cysteine in the active site and a requirement for aspartic acid at the cleavage site in target proteins. The '-ase' suffix itself comes from 'diastase' and ultimately Greek roots meaning 'to loosen'. Related coinages include protease, lipase, kinase, and amylase, all built on the same enzymatic naming pattern.
How caspase is actually used
Strictly a technical term of molecular biology and biochemistry, used almost exclusively in scientific writing. It is countable, referring to individual members of the family, which are conventionally numbered (caspase-3, caspase-8, caspase-9) and classified as initiators or executioners according to their role in apoptosis.
Easily confused with caspase
Catalase is an antioxidant enzyme that breaks down hydrogen peroxide, whereas a caspase is a protease that drives apoptosis.