Trypsin and chemotrypsin colorimetric assay
Dr Engelbert Buxbaum
(by engelbert_buxbaum from hotmail.com)
Sat May 19 11:37:09 EST 2012
In article <mailman.235.1335815731.3456.methods from net.bio.net>,
Gerchman from research.haifa.ac.il says...
> I am looking for recommendations for Trypsin and
> Chemotrypsin colorimetric assay, preferably not in the UV range.
The classical assay is with azocasein (e.g. Charney and Tomarelli, JBC
171 (1947) 501), this colorimetric assay is read at 440 nm.
More modern assays work with Förster's resonance energy transfer: the
protein is labeled with two fluorescent dyes in resonance (emission
spectrum of the first overlaps the absorption spectrum of the second).
As the protein is digested, distance between the dyes increases and
resonance (which decreases with the 6th power of the distance) is
abolished. The advantage is that you do not need to separate hydrolyzed
product from non-hydrolyzed substrate and can measure while the reaction
is occurring. Therefore, this type of assay is suitable for large-scale
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