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Journal of Nanomaterials
Volume 2013, Article ID 468105, 9 pages
Research Article

A Novel Complex: A Quantum Dot Conjugated to an Active T7 RNA Polymerase

1Niels Bohr Institute, University of Copenhagen, 2100 Copenhagen, Denmark
2Institute of Biology, Eötvös Loránd University, Budapest 1053, Hungary
3Institute of Biology, University of Copenhagen, 2200 Copenhagen, Denmark

Received 28 January 2013; Accepted 17 April 2013

Academic Editor: Christophe Merlin

Copyright © 2013 Mette Eriksen et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


To perform single-molecule studies of the T7 RNA polymerase, it is crucial to visualize an individual T7 RNA polymerase, for example, through a fluorescent signal. We present a novel complex combining two different molecular functions, an active T7 RNA polymerase and a highly luminescent nanoparticle, a quantum dot. The complex has the advantage of both constituents: the complex can traffic along DNA and simultaneously be visualized, both at the ensemble and at the single-molecule level. The labeling was mediated through an in vivo biotinylation of a His-tagged T7 RNA polymerase and subsequent binding of a streptavidin-coated quantum dot. Our technique allows for easy purification of the quantum dot labeled T7 RNA polymerases from the reactants. Also, the conjugation does not alter the functionality of the polymerase; it retains the ability to bind and transcribe.