The chromogenic beta-lactamase substrate CENTA is at least five times cheaper than the other famous substrate nitrocefin and can be used with most enzymes, still, nitrocefin is preferred. Any particular reason?
Nitrocefin has a much larger absorbance increase upon hydrolysis, and the measurement is made at a longer wavelength (Δɛ = +17,500 M−1cm−1 at 490 nm) than CENTA (Δɛ = +6,400 M−1cm−1 at 405 nm). The longer wavelength is helpful because (a) it is squarely in the visible range so you can see the color change by eye easily, and (b) it helps reduce the background from other substances that might be present in the measurement.
Nitrocefin has a much larger absorbance increase upon hydrolysis, and the measurement is made at a longer wavelength (Δɛ = +17,500 M−1cm−1 at 490 nm) than CENTA (Δɛ = +6,400 M−1cm−1 at 405 nm). The longer wavelength is helpful because (a) it is squarely in the visible range so you can see the color change by eye easily, and (b) it helps reduce the background from other substances that might be present in the measurement.
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