The interaction of trypsin with camptothecin(CPT) in vitro was studied by ultraviolet(UV) absorption spectral and fluorescence spectral methods.Making out value of Ki according to the ratio between 1/v and the amount of inhibitor contributes to the conclusion that CPT is a noncompetitive inhibitor.The interaction between CPT and trypsin is quite strong.CPT can affect the conformation of trypsin in some degree.Fluorescence quenching contributes to nonradiative energy-transfer,which results a static quenching of CPT to trypsin.Their binding constants and the binding sites of CPT were determined.
