Amplification of color yield of chromogenic substrates using p-dimethylaminocinnamaldehyde

Hau C. Kwaan*, Robert B. Friedman, Marija Szczecinski

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

8 Scopus citations


A method is described for amplifying the color of 4-nitroaniline which is produced during enzyme catalyzed amidolysis of synthetic chromogenic substrates. The liberated chromogen is directly coupled with p-dimethylaminocinnamaldehyde to yield a colored schiffbase compound. The color complex has an absorption maximum at 570 nm and, under the reaction conditions described, has a molar absorbancy of 9.1 × 104. The application of this method is presented for the enzyme urokinase using two different chromogenic substrates. A micromethod adaptation of this method is also described. This method can be used to amplify the color obtained in all enzyme assays where 4-nitroaniline is the liberated chromogen.

Original languageEnglish (US)
Pages (from-to)5-13
Number of pages9
JournalThrombosis Research
Issue number1
StatePublished - Jul 1978

ASJC Scopus subject areas

  • Hematology


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