Single-Molecule Enzymatic Dynamics
Enzymatic turnovers of single cholesterol oxidase molecules are observed in real time by monitoring the emission from the enzyme's fluorescent active site, flavin adenine dinucleotide (FAD). Although chemical kinetics, the Michaelis-Menten mechanism in particular, holds as a good approximation, statistical analyses of single-molecule trajectories reveal fluctuations in the rate of the activation step in the Michaelis-Menten mechanism. There exists a memory effect: an enzymatic turnover is not independent of its previous turnovers. This non-Markovian behavior, otherwise hidden in ensemble-averaged measurements, is attributed to slow fluctuations of protein conformations. Static heterogeneity and dynamical variation of reaction rates, essentially indistinguishable in ensemble-averaged experiments, can now be determined separately by the real-time single-molecule approach.
- Research Organization:
- Pacific Northwest National Laboratory (PNNL), Richland, WA (US)
- Sponsoring Organization:
- USDOE
- DOE Contract Number:
- AC05-76RL01830
- OSTI ID:
- 1033482
- Report Number(s):
- PNNL-SA-30273; KC0301020; KP1301010
- Journal Information:
- Science, Journal Name: Science Vol. 282; ISSN 0193-4511; ISSN SCEHDK
- Country of Publication:
- United States
- Language:
- English
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