Specific Binding of Thionine to the Active Site of Trypsin

摘要: Abstract The binding of thionine (3,6-diaminophenothiazine) to trypsin is associated with a red shift in the visible absorption spectrum dye. Spectrophotometric titration and equilibrium dialysis measurements are consistent presence single thionine-binding site on molecule. At pH 7 4°, Kdiss for trypsin-thionine complex 1.2 x 10-5 m. dye displaced from by substrates, competitive inhibitors, chemically reactive substrate analogue 1-chloro-3-tosylamido-7-amino-2-heptanone. Thus, overlaps active region trypsin. binds very weakly trypsinogen, little spectral perturbation. Thionine, at low concentrations, also chymotrypsin chymotrypsinogen, showing same characteristics value 4.5 10-4 m 7.0 4°. not affected or analogues; hence, does appear include any part region.