Fluorescence monitoring of the conformational change in alpha(2)-macroglobulin induced by trypsin under second-order conditions: The macroglobulin acts both as a substrate and a competitive inhibitor of the protease

Ozer I., Simsek H.

JOURNAL OF ENZYME INHIBITION, cilt.15, sa.2, ss.101-110, 2000 (SCI İndekslerine Giren Dergi) identifier

  • Cilt numarası: 15 Konu: 2
  • Basım Tarihi: 2000
  • Sayfa Sayıları: ss.101-110


The reaction of bovine pancreatic trypsin with human plasma alpha(2)-macroglobulin (alpha(2)M) was studied at 25 degrees C, using equimolar mixtures of E and I in 50 mM potassium phosphate buffer, pH 7. The conformational change in alpha(2)M was monitored through the increase in protein fluorescence at 320 nm (exc lambda, 280 nm). At [alpha(2)M](0) = [E](0) = 11.5-200 nM, the fluorescence change data fit the integrated second-order rate equation, (F-infinity - F-0)/(F-infinity - F-l) = 1 + k(i,obsd) [alpha(2)M](0)t, indicating that cleavage of the bait region in alpha(2)M was the rate-determining step.