Primary structure of p-momorcharin, a ribosome-inactivating protein from the seeds of Momordica Charantia Linn (Cucurbitaceae)

Thecompleteaminoacidsequenceofβ-momorcharin,aribosome-inactivatingproteinfromtheseedsofMomordicacharantiaLinn(Cucurbitaceae)hasbeendetermined.Thishasbeendonebythesequenceanalysisofpeptidesobtainedbyenzymaticdigestionwithtrypsin,chymotrypsinandS.aureusV8protease,aswellasbychemicalcleavagewithBNPS-skatole.Theproteinconsistsof249aminoacidresiduescontainingoneasparagine-linkedsugargroupattachedtothesiteofAsn51andhasacalculatedrelativemolecularmassof28,452Dawithoutadditionofthecarbohydrate.Comparisonofthissequencewiththoseoftrichosanthinandotherribosome-inactivatingproteinsfromdifferentspeciesofplantsshowsasignificanthomologywitheachother.Regardingthesimilarityoftheirbiologicalproperties,anactivedomainoftheseproteinshasbeenpredictedhere.