C O M M U N I C A T I O N S
conditions. Thus, the spatial resolution obtained with this fluoro-
genic probe based approach allows mapping of the hypobromite
flux from such a highly active crystal. The freely diffusing hypo-
bromite can be seen as a vehicle transporting highly activated
oxygen generated at the surface from the mild hydrogen peroxide
into the bulk solution. There it can freely oxidize or brominate bulky
substrates which usually have a poor access to surface-bound
reactive species such as peroxo-titanium in silica which are common
in oxidation chemistry.20
In summary, we present a new fluorescence microscopy based
method to study the formation of HOBr using the fluorogenic substrate
APF in haloperoxidase type reactions performed by a haloperoxidase
enzyme and WO42--LDH crystals.
Acknowledgment. The authors are grateful to the Belgian
Federal Government (IAP-VI) and to the KULeuven Research Fund
(CECAT and GOA) for financial support. V.M.M., G.D.C., and
M.B.J.R. are grateful to Ministerio de Educacio´n y Ciencia, FWO,
and IWT-Vlaanderen, respectively, for fellowships. Novozymes is
acknowledged for kindly donating the BPO enzyme sample.
Figure 1. (A and B) Representative parts of an intensity-time trace for
(A) a CurVularia Verruculosa enzyme and (B) a WO42--LDH crystal,
measured at a laser power of 5 µW and binned at 10 ms. (C and D)
Histograms of the time-averaged activities in traces of the enzymes, n )
94 (C) and the WO42--LDH crystals, n ) 65 (D). The inset in (C) shows
a zoom of the histogram with a Gaussian fit (solid line; µ ) 0.7 s-1 and σ
) 0.23 s-1).
Supporting Information Available: Figures S1-S10, supporting
methods, and data analysis. This material is available free of charge
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