A virus-based single-enzyme nanoreactor

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Most enzyme studies are carried out in bulk aqueous solution, at the so-called ensemble level, but more recently studies have appeared in which enzyme activity is measured at the level of a single molecule, revealing previously unseen properties1,2,3,4. To this end, enzymes have been chemically or physically anchored to a surface, which is often disadvantageous because it may lead to denaturation. In a natural environment, enzymes are present in a confined reaction space, which inspired us to develop a generic method to carry out single-enzyme experiments in the restricted spatial environment of a virus capsid. We report here the incorporation of individual horseradish peroxidase enzymes in the inner cavity of a virus, and describe single-molecule studies on their enzymatic behaviour. These show that the virus capsid is permeable for substrate and product and that this permeability can be altered by changing pH.

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Figure 1: Characterization of CCMV and the empty CCMV capsid.
Figure 2: Inclusion of HRP in the virus capsid.
Figure 3: Enzyme activity in the presence of single capsids.
Figure 4: Single-capsid experiments.


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This work was supported by the Council for Chemical Sciences of the Netherlands Organization for Scientific Research (NWO-CW) through a TOP grant to R.J.M.N. and Veni & Vidi Innovative Research Grants to J.J.L.M.C., and by the Royal Netherlands' Academy for Arts and Sciences (R.J.M.N.). The protein Dronpa was a generous gift from J. Hofkens, University of Leuven (Belgium).

Author information

M.C., H.E., J.C. and R.N conceived and designed the experiments; M.C. carried out the capsid isolation and encapsulation experiments and M.C., V.C. and H.E. performed the fluorescence spectroscopy. B.V. contributed to the capsid isolation and encapsulation studies. H.E. analysed the fluorescence data. A.R., P.C., J.M. and R.N. facilitated the fluorescence microscope and N.S. provided the cryo-TEM data.M.C., H.E., J.C and R.N co-wrote the manuscript. All authors discussed the results and commented on the manuscript.

Correspondence to Hans Engelkamp or Jeroen J. L. M. Cornelissen.

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Comellas-Aragonès, M., Engelkamp, H., Claessen, V. et al. A virus-based single-enzyme nanoreactor. Nature Nanotech 2, 635–639 (2007) doi:10.1038/nnano.2007.299

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