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

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Ozer I., Simsek H.

JOURNAL OF ENZYME INHIBITION, vol.15, no.2, pp.101-110, 2000 (Journal Indexed in SCI)

• Publication Type: Article / Article
• Volume: 15 Issue: 2
• Publication Date: 2000
• Title of Journal : JOURNAL OF ENZYME INHIBITION
• Page Numbers: pp.101-110

Abstract

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.