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. Author manuscript; available in PMC: 2010 Jul 15.
Published in final edited form as: Bioorg Med Chem. 2009 Jun 22;17(14):5027–5037. doi: 10.1016/j.bmc.2009.05.070

Figure 1.

Figure 1

a) Nitrocefin assay principle. A change in absorbance at λ=495 nm is measured after the cephalosporin core of nitrocefin is hydrolyzed by β-lactamase b) CCF2 (FRET) assay principle. In the intact CCF2 substrate, coumarin moiety's donor FRET resulting from λ= 409 nm excitation is efficiently quenched by the acceptor fluorescein moiety; hydrolysis of the β-lactam leads to the increase of a donor fluorescence measured at 447 nm and simultaneous decrease of an acceptor fluorescence at measured at 520 nm.