Influence of enzyme conformational changes on catalytic activity investigated by circular dichroism spectroscopy

Abstract

Enzyme activity is dependent on native conformational integrity. Here we present a simple laboratory exercise based on dichroism spectroscopy in which the change in enzyme structure induced by denaturation is correlated with the loss of catalytic activity. The results of circular dichroism spectra show that enzyme denaturation by either trifluoroethanol (enhancement of α-helix structure) or guanidinium chloride (reduction of α-helix and enhancement of random coil structure) leads to a concomitant reduction in enzyme activity, which demonstrates the relationship between structure and catalytic activity of the enzyme. This simple experimental approach demonstrates that only a single native protein (enzyme) conformation has the ability to catalyze substrate hydrolysis. © 2003 by The International Union of Biochemistry and Molecular Biology.