Article abstract
Nature Chemical Biology 2, 87 - 94 (2005)
Published online: 25 December 2005 | doi:10.1038/nchembio759
There is an Erratum (March 2006) associated with this Article.
Ever-fluctuating single enzyme molecules: Michaelis-Menten equation revisited
Brian P English1, Wei Min1, Antoine M van Oijen1,4, Kang Taek Lee1,4, Guobin Luo1, Hongye Sun1,4, Binny J Cherayil1,2, S C Kou3 & X Sunney Xie1
Abstract
Enzymes are biological catalysts vital to life processes and have attracted century-long investigation. The classic Michaelis-Menten mechanism provides a highly satisfactory description of catalytic activities for large ensembles of enzyme molecules. Here we tested the Michaelis-Menten equation at the single-molecule level. We monitored long time traces of enzymatic turnovers for individual 
-galactosidase molecules by detecting one fluorescent product at a time. A molecular memory phenomenon arises at high substrate concentrations, characterized by clusters of turnover events separated by periods of low activity. Such memory lasts for decades of timescales ranging from milliseconds to seconds owing to the presence of interconverting conformers with broadly distributed lifetimes. We proved that the Michaelis-Menten equation still holds even for a fluctuating single enzyme, but bears a different microscopic interpretation.
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA.
- Department of Inorganic & Physical Chemistry, Indian Institute of Science, Bangalore 560012, India.
- Department of Statistics, Harvard University, Cambridge, Massachusetts 02138, USA.
- Present addresses: Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, 240 Longwood Avenue, Boston, Massachusetts 02115, USA (A.M.v.O.); Department of Chemistry, University of Chicago, Chicago, Illinois 60637, USA (K.T.L.); Applied Biosystems, 850 Lincoln Center Dr., Foster City, California 94404, USA (H.S.).
Correspondence to: X Sunney Xie1 e-mail: xie@chemistry.harvard.edu
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