| BackgroundInformation | Apoptosisisanevolutionarilyconservedformofcellsuicide,whichfollowsaspecializedcellularprocess.Thecentralcomponentofthisprocessisacascadeofproteolyticenzymescalledcaspases.Theseenzymesparticipateinaseriesofreactionsthataretriggeredinresponsetopro-apoptoticsignalsandresultinthecleavageofproteinsubstrates,causingthedisassemblyofthecell1. 
 CaspaseshavebeenidentifiedinorganismsrangingfromC.eleganstohumans.Themammaliancaspasesplaydistinctrolesinapoptosisandinflammation.Inapoptosis,caspasesareresponsIBLeforproteolyticcleavagesthatleadtocelldisassembly(effectorcaspases),andareinvolvedinupstreamregulatoryevents(initiatorcaspases).Anactivecaspaseconsistsoftwolargeandtwosmallsubunitsthatformtwoheterodimers,whichassociateinatetramer2-4.Incommonwithotherproteases,caspasesaresynthesizedasprecursorsthatundergoproteolyticmaturation,eitherautocatalyticallyorinacascadebyenzymeswithsimilarspecificity5.
 
 Caspaseenzymesspecificallyrecognizea4or5aminoacidsequenceonthetargetsubstrate,whichnecessarilyincludesanasparticacidresidue.Thisresidueisthetargetforcleavage,whichoccursatthecarbonylendoftheasparticacidresidue6.Caspasescanbedetectedviaimmunoprecipitation,immunoblottingtechniquesusingcaspasespecificantibodies,orbyemployingFluorochromesubstrates,whichbecomefluorescentuponcleavagebythecaspase.
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