Title: Stretched exponential decay and correlations in the catalytic activity of fluctuating single lipase molecules
Authors: Flomenbom, O ×
Velonia, K
Loos, D
Masuo, S
Cotlet, M
Engelborghs, Yves
Hofkens, Johan
Rowan, AE
Nolte, RJM
Van der Auweraer, Mark
De Schryver, Frans
Klafter, J #
Issue Date: Feb-2005
Publisher: Natl acad sciences
Series Title: Proceedings of the National Academy of Sciences of the United States of America vol:102 issue:7 pages:2368-2372
Abstract: Single-molecule techniques offer a unique tool for studying the dynamical behavior of individual molecules and provide the possibility to construct distributions from individual events rather than from a signal stemming from an ensemble of molecules. In biological systems, known for their complexity, these techniques make it possible to gain insights into the detailed spectrum of molecular conformational changes and activities. Here, we report on the direct observation of a single lipase-catalyzed reaction for extended periods of time (hours), by using confocal fluorescence microscopy. When adding a profluorescent substrate, the monitored enzymatic activity appears as a trajectory of "on-state" and "off-state" events. The waiting time probability density function of the off state and the state-correlation function fit stretched exponentials, independent of the substrate concentration in a certain range. The data analysis unravels oscillations in the logarithmic derivative of the off-state waiting time probability density function and correlations between off-state events. These findings imply that the fluctuating enzyme model, which involves a spectrum of enzymatic conformations that interconvert on the time scale of the catalytic activity, best describes the observed enzymatic activity. Based on this model, values for the coupling and reaction rates are extracted.
ISSN: 0027-8424
Publication status: published
KU Leuven publication type: IT
Appears in Collections:Molecular Imaging and Photonics
Biochemistry, Molecular and Structural Biology Section
× corresponding author
# (joint) last author

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