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Conformational Cycle of a Single Working Enzyme Noam Agmon*

Summary: Conformational Cycle of a Single Working Enzyme
Noam Agmon*
The Fritz Haber Research Center, Department of Physical Chemistry, The Hebrew UniVersity,
Jerusalem 91904, Israel
ReceiVed: April 4, 2000; In Final Form: May 30, 2000
By simultaneous analysis of the on-time distribution and autocorrelation function of a single working cholesterol
oxidase enzyme, a diffusional model reveals the coupling of conformation change with enzyme action. Active-
site oxidation induces a conformational change that opens the path for substrate entry. Its binding, in turn,
induces the reverse protein relaxation process, which tightens the active site, thereby reducing the rate of
product release.
1. Introduction
The idea that enzyme activity may depend on conformational
change has been discussed extensively,1-6 but a direct demon-
stration of the effect has not yet been produced. X-ray7,8 and
hydrogen-deuterium exchange data9 suggest that enzymes
assume different conformational states that change in response
to substrate or cofactor binding. However, time-resolved data
with a theoretical interpretation connecting, quantitatively,
conformational change with enzyme activity are still to be


Source: Agmon, Noam - Institute of Chemistry, Hebrew University of Jerusalem


Collections: Chemistry